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123-750: Body Wars was a motion simulator attraction inside the Wonders of Life pavilion at the Walt Disney World Resort 's Epcot . Riders would be taken on a mission by the fictional Miniaturized Exploration Technologies corporation (Stylized as MET) to study the effects of the white blood cells on a splinter inside the left index finger of a volunteer. The attraction used the Advanced Technology Leisure Application Simulator technology previously seen at Disneyland's Star Tours attraction. The ride

246-519: A gain medium , a mechanism to energize it, and something to provide optical feedback . The gain medium is a material with properties that allow it to amplify light by way of stimulated emission. Light of a specific wavelength that passes through the gain medium is amplified (power increases). Feedback enables stimulated emission to amplify predominantly the optical frequency at the peak of the gain-frequency curve. As stimulated emission grows, eventually one frequency dominates over all others, meaning that

369-471: A lens system, as is always included, for instance, in a laser pointer whose light originates from a laser diode . That is possible due to the light being of a single spatial mode. This unique property of laser light, spatial coherence , cannot be replicated using standard light sources (except by discarding most of the light) as can be appreciated by comparing the beam from a flashlight (torch) or spotlight to that of almost any laser. A laser beam profiler

492-488: A motion simulator ride named Body Wars. The sponsor of Wonders of Life would be MetLife . Construction of the pavilion began in February of that year. The Wonders of Life pavilion would officially open to the general public on October 19, 1989. Upon opening, Body Wars had a wait time of 90 minutes. Just two months after opening, a similar ride named Star Tours opened at Disney's Hollywood Studios . Body Wars received

615-464: A broad spectrum of light or emit different wavelengths of light simultaneously. Certain lasers are not single spatial mode and have light beams that diverge more than is required by the diffraction limit . All such devices are classified as "lasers" based on the method of producing light by stimulated emission. Lasers are employed where light of the required spatial or temporal coherence can not be produced using simpler technologies. A laser consists of

738-526: A bruise on his arm, but wasn't shown inside of. The queue would begin with the logo of the MET Company, with various images depicting the company and the inside of the human body. Until 1993, signage would be hung up stating that the company was founded in 2063, as well as their motto "Pioneering the Universe Within". This would lead into the first of two "Dermatopic Purification" stations, before

861-477: A cell count when she was accidentally pulled into a capillary. Captain Braddock followed Dr. Lair into the vein, entering an unauthorized area. The captain steered Bravo past the heart and into the right ventricle. The guests entered the lungs where Dr. Lair was being attacked by a white blood cell. Braddock used his lasers to free Dr. Lair. By now, the ship was very low on power. Dr. Lair suggested that they use

984-504: A chain reaction. The materials chosen for lasers are the ones that have metastable states , which stay excited for a relatively long time. In laser physics , such a material is called an active laser medium . Combined with an energy source that continues to "pump" energy into the material, it is possible to have enough atoms or molecules in an excited state for a chain reaction to develop. Lasers are distinguished from other light sources by their coherence . Spatial (or transverse) coherence

1107-436: A coherent beam has been formed. The process of stimulated emission is analogous to that of an audio oscillator with positive feedback which can occur, for example, when the speaker in a public-address system is placed in proximity to the microphone. The screech one hears is audio oscillation at the peak of the gain-frequency curve for the amplifier. For the gain medium to amplify light, it needs to be supplied with energy in

1230-471: A constant speed or velocity is reached. At constant speed, visual cues give cues of motion until another acceleration takes place and the body's motion sensors once more send signals to the brain. In simulator motion platforms, after an initial acceleration is produced, the platform is re-set to a neutral position at a rate below human motion threshold so that the subject does not detect the so-called "wash out" phase of simulator motion cueing. The motion system

1353-419: A device lacks the spatial and temporal coherence achievable with lasers. Such a device cannot be described as an oscillator but rather as a high-gain optical amplifier that amplifies its spontaneous emission. The same mechanism describes so-called astrophysical masers /lasers. The optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to

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1476-399: A drop of water. The guests' vehicle, Bravo 229, moved from the bay to the miniaturization room, where technicians focused a "particle reducer" on the ship. The ship and crew mates were shrunk and sent into the subject's body, under his skin. White blood cells were seen on their way to destroy his splinter. The guests arrived at the splinter, meeting with Dr. Cynthia Lair. She began to take

1599-478: A fluid called the endolymph. In each canal, there is a section where the diameter is larger than the rest of the canal. This section is called the ampulla and is sealed by a flap called the cupula. Angular accelerations are detected as follows: an angular acceleration causes the fluid in the canals to move, deflecting the cupula. The nerves in the cupula report the motion to both the brain and oculomotor muscles, stabilizing eye movements. A transfer function model between

1722-508: A gain medium must have a gain bandwidth sufficiently broad to amplify those frequencies. An example of a suitable material is titanium -doped, artificially grown sapphire ( Ti:sapphire ), which has a very wide gain bandwidth and can thus produce pulses of only a few femtoseconds duration. Such mode-locked lasers are a most versatile tool for researching processes occurring on extremely short time scales (known as femtosecond physics, femtosecond chemistry and ultrafast science ), for maximizing

1845-480: A given pulse energy, this requires creating pulses of the shortest possible duration utilizing techniques such as Q-switching . The optical bandwidth of a pulse cannot be narrower than the reciprocal of the pulse width. In the case of extremely short pulses, that implies lasing over a considerable bandwidth, quite contrary to the very narrow bandwidths typical of CW lasers. The lasing medium in some dye lasers and vibronic solid-state lasers produces optical gain over

1968-484: A hallway with in queue TV sets, and the second of two "Dermatopic Purification" stations. Dr. Cynthia Lair had volunteered to be miniaturized to observe a splinter . The guests were told they would board vehicle Bravo 229 and would be shrunk. Their mission was to meet up with Dr. Lair and bring her out. Captain Braddock would be the guests' pilot. Guests learned that their "LGS 250"-type probe vehicle weighed approximately 26 tons, but once miniaturized, weighed less than

2091-399: A higher energy level with energy difference ΔE, it will not stay that way forever. Eventually, a photon will be spontaneously created from the vacuum having energy ΔE. Conserving energy, the electron transitions to a lower energy level that is not occupied, with transitions to different levels having different time constants. This process is called spontaneous emission . Spontaneous emission is

2214-412: A human test subject. Values of 0.5 ∘ / sec 2 {\displaystyle 0.5^{\circ }/\sec ^{2}} have been reported for pitch and roll accelerations in a flight simulator. The above studies indicate that the pilot's vestibular system detects accelerations before the aircraft instruments displays them. This can be considered an inner control loop in which

2337-425: A larger market of more generalized "craft-oriented" simulation, entertainment, and virtual reality systems. Motion platforms are commonly used in the field of engineering for analysis and verification of vehicle performance and design. The ability to link a computer-based dynamic model of a particular system to physical motion gives the user the ability to feel how the vehicle would respond to control inputs without

2460-476: A laser beam, it is highly collimated : the wavefronts are planar, normal to the direction of propagation, with no beam divergence at that point. However, due to diffraction , that can only remain true well within the Rayleigh range . The beam of a single transverse mode (gaussian beam) laser eventually diverges at an angle that varies inversely with the beam diameter, as required by diffraction theory. Thus,

2583-471: A laser is normally a material of controlled purity, size, concentration, and shape, which amplifies the beam by the process of stimulated emission described above. This material can be of any state : gas, liquid, solid, or plasma . The gain medium absorbs pump energy, which raises some electrons into higher energy (" excited ") quantum states . Particles can interact with light by either absorbing or emitting photons. Emission can be spontaneous or stimulated. In

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2706-484: A mixed reception from guests, as some praised the thrilling experience, but others complained of motion sickness and nausea since it was considered to be a rough ride. In the late 90’s, tensions between MetLife and Disney began to occur as MetLife would often setup tables at the pavilion to sell park guests life insurance which is a not allowed. After MetLife's sponsorship expired in June 2001, Epcot would continue to operate

2829-423: A motion platform (if fitted) works in synchronization to the external visual scene. As discussed above, in the real world motion cues are processed by the brain before visual changes, and this must be followed in a simulator or dizziness and even nausea can occur in some people, so called "simulator sickness". For example, if the occupant commands the vehicle to roll to the left, the visual displays must also roll by

2952-690: A motion simulator cabinet was Space Tactics (1981), a space combat simulator that had a cockpit cabinet where the screen moved in sync with the on-screen action. The "taikan" trend later began when Yu Suzuki 's team at Sega (later known as Sega AM2 ) developed Hang-On (1985), a racing video game where the player sits on and moves a motorbike replica to control the in-game actions. Suzuki's team at Sega followed it with hydraulic motion simulator cockpit cabinets for rail shooters such as Space Harrier (1985), racing games such as Out Run (1986), and arcade combat flight simulators such as After Burner (1987) and G-LOC: Air Battle (1990). One of

3075-418: A multi-level system as a method for obtaining the population inversion, later a main method of laser pumping. Townes reports that several eminent physicists—among them Niels Bohr , John von Neumann , and Llewellyn Thomas —argued the maser violated Heisenberg's uncertainty principle and hence could not work. Others such as Isidor Rabi and Polykarp Kusch expected that it would be impractical and not worth

3198-484: A neuron receives such a signal, it sends it on to an adjacent neuron through a bridge called a synapse. A synapse "sparks" the impulse between neurons through electrical and chemical means. These sensory signals are processed by the brain in response to signals that travel along motor nerves. Motor neurons, with their special fibres, carry these signals to muscles, which are instructed to either contract or relax. These are all sensors of acceleration, and do not respond when

3321-591: A price range from $ 1,000 to US$ 9,000. Within the 2000s (decade), several individuals and business entities have developed these smaller, more affordable motion systems. Most of these systems were developed mainly by flight simulation enthusiasts, were sold as do it yourself projects, and could be assembled in the home from common components for around one thousand US dollars ($ 1,000). Recently, there has been increased market interest in motion platforms for more personal, in-home, use. The application of these motion systems extends beyond just flight training simulation into

3444-564: A price range from $ 10,000 to US$ 99,000. Typically the space requirements for such a platform are modest requiring only a portion of an arcade room and a smaller range of motion is provided via similar, less expensive, control systems than the high-end platforms. In the 1980s, it became a trend for arcade video games to use hydraulic motion simulator arcade cabinets . The trend was sparked by Sega 's "taikan" games, with "taikan" meaning "body sensation" in Japanese. Sega's first game to use

3567-441: A process called pumping . The energy is typically supplied as an electric current or as light at a different wavelength. Pump light may be provided by a flash lamp or by another laser. The most common type of laser uses feedback from an optical cavity —a pair of mirrors on either end of the gain medium. Light bounces back and forth between the mirrors, passing through the gain medium and being amplified each time. Typically one of

3690-468: A quantum-mechanical effect and a direct physical manifestation of the Heisenberg uncertainty principle . The emitted photon has a random direction, but its wavelength matches the absorption wavelength of the transition. This is the mechanism of fluorescence and thermal emission . A photon with the correct wavelength to be absorbed by a transition can also cause an electron to drop from the higher to

3813-624: A real flight control system in a laboratory, integrating the pilot with the electrical, mechanical, and hydraulic components that exist on the real aircraft, a complete system evaluation can be conducted prior to initial flight testing. This type of testing allows the simulation of "seeded faults" (i.e. an intentional hydraulic leak, software error, or computer shutdown) which serve to validate that an aircraft's redundant design features work as intended. A test pilot can also help identify system deficiencies such as inadequate or missing warning indicators, or even unintended control stick motion. This testing

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3936-432: A seminar on this idea, and Charles H. Townes asked him for a copy of the paper. In 1953, Charles H. Townes and graduate students James P. Gordon and Herbert J. Zeiger produced the first microwave amplifier, a device operating on similar principles to the laser, but amplifying microwave radiation rather than infrared or visible radiation. Townes's maser was incapable of continuous output. Meanwhile, in

4059-423: A simulation of flight or other motion. Some examples: Some driving and flying simulation games allow the use of specialized controllers such as steering wheels, foot pedals or joysticks. Certain game controllers designed in recent years have employed haptic technology to provide realtime, tactile feedback to the user in the form of vibration from the controller. A motion simulator takes the next step by providing

4182-431: A small volume of material at the surface of a workpiece can be evaporated if it is heated in a very short time, while supplying the energy gradually would allow for the heat to be absorbed into the bulk of the piece, never attaining a sufficiently high temperature at a particular point. Other applications rely on the peak pulse power (rather than the energy in the pulse), especially to obtain nonlinear optical effects. For

4305-646: A very narrow frequency spectrum . Temporal coherence can also be used to produce ultrashort pulses of light with a broad spectrum but durations as short as an attosecond . Lasers are used in optical disc drives , laser printers , barcode scanners , DNA sequencing instruments , fiber-optic and free-space optical communications, semiconductor chip manufacturing ( photolithography , etching ), laser surgery and skin treatments, cutting and welding materials, military and law enforcement devices for marking targets and measuring range and speed, and in laser lighting displays for entertainment. Semiconductor lasers in

4428-430: A wide bandwidth, making a laser possible that can thus generate pulses of light as short as a few femtoseconds (10 s). In a Q-switched laser, the population inversion is allowed to build up by introducing loss inside the resonator which exceeds the gain of the medium; this can also be described as a reduction of the quality factor or 'Q' of the cavity. Then, after the pump energy stored in the laser medium has approached

4551-492: A wide range of technologies addressing many different motivations. Some lasers are pulsed simply because they cannot be run in continuous mode. In other cases, the application requires the production of pulses having as large an energy as possible. Since the pulse energy is equal to the average power divided by the repetition rate, this goal can sometimes be satisfied by lowering the rate of pulses so that more energy can be built up between pulses. In laser ablation , for example,

4674-445: Is coherent . Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as optical communication, laser cutting , and lithography . It also allows a laser beam to stay narrow over great distances ( collimation ), a feature used in applications such as laser pointers , lidar , and free-space optical communication . Lasers can also have high temporal coherence , which permits them to emit light with

4797-522: Is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation . The word laser is an anacronym that originated as an acronym for light amplification by stimulated emission of radiation . The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories , based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow . A laser differs from other sources of light in that it emits light that

4920-444: Is a function of the way our brain interprets signals from our various sensory systems, such as sight, sound, balance and touch. Special sensory pick-up units (or sensory "pads") called receptors translate stimuli into sensory signals. External receptors (exteroceptors) respond to stimuli that arise outside the body, such as the light that stimulates the eyes, sound pressure that stimulates the ear, pressure and temperature that stimulates

5043-404: Is a transition between energy levels that match the energy carried by the photon or phonon. For light, this means that any given transition will only absorb one particular wavelength of light. Photons with the correct wavelength can cause an electron to jump from the lower to the higher energy level. The photon is consumed in this process. When an electron is excited from one state to that at

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5166-480: Is also required for three-level lasers in which the lower energy level rapidly becomes highly populated, preventing further lasing until those atoms relax to the ground state. These lasers, such as the excimer laser and the copper vapor laser, can never be operated in CW mode. In 1917, Albert Einstein established the theoretical foundations for the laser and the maser in the paper " Zur Quantentheorie der Strahlung " ("On

5289-413: Is called an optical amplifier . When an optical amplifier is placed inside a resonant optical cavity, one obtains a laser. For lasing media with extremely high gain, so-called superluminescence , light can be sufficiently amplified in a single pass through the gain medium without requiring a resonator. Although often referred to as a laser (see, for example, nitrogen laser ), the light output from such

5412-471: Is currently being transformed into the new Play! pavilion (construction is under way). The exit area has had the same treatment, with all signage removed. Red archive tags have been applied to the beginning MET Sign, and to the Body Wars safety information sign near the exit. On February 21, 2019, it was announced that the new Play! Pavilion would be replacing the entire Wonders of Life pavilion, including

5535-462: Is emitted by stimulated emission is identical to the photon that triggered its emission, and both photons can go on to trigger stimulated emission in other atoms, creating the possibility of a chain reaction . For this to happen, many of the atoms or molecules must be in the proper excited state so that the photons can trigger them. In most materials, atoms or molecules drop out of excited states fairly rapidly, making it difficult or impossible to produce

5658-421: Is formed by single-frequency quantum photon states distributed according to a Poisson distribution . As a result, the arrival rate of photons in a laser beam is described by Poisson statistics. Many lasers produce a beam that can be approximated as a Gaussian beam ; such beams have the minimum divergence possible for a given beam diameter. Some lasers, particularly high-power ones, produce multimode beams, with

5781-443: Is frequently used in the field, meaning "to give off coherent light," especially about the gain medium of a laser; when a laser is operating, it is said to be " lasing ". The terms laser and maser are also used for naturally occurring coherent emissions, as in astrophysical maser and atom laser . A laser that produces light by itself is technically an optical oscillator rather than an optical amplifier as suggested by

5904-421: Is impossible. In some other lasers, it would require pumping the laser at a very high continuous power level, which would be impractical, or destroying the laser by producing excessive heat. Such lasers cannot be run in CW mode. The pulsed operation of lasers refers to any laser not classified as a continuous wave so that the optical power appears in pulses of some duration at some repetition rate. This encompasses

6027-454: Is lined with hairs connected to nerve endings and is partially filled with fluid. When the head experiences acceleration the fluid moves within the canals, causing the hair follicles to move from their initial orientation. In turn the nerve endings signal to the brain, which interprets them as acceleration in the three rotations pitch, roll, or yaw. The vestibular system generates reflexes to maintain perceptual and postural stability, compared to

6150-405: Is necessary to simulate extremely high risk events that cannot be conducted in flight but nonetheless must be demonstrated. While 6 degree-of-freedom motion is not necessary for this type of testing, the visual screen allows the pilot to "fly" the aircraft while the faults are simultaneously triggered. Motion simulators are sometimes used in theme parks or amusement parks to give the park guests

6273-591: Is no longer in operation along with the other attractions inside the Wonders of Life pavilion, which opened on October 19, 1989, and closed on January 1, 2007. On January 22, 1988, Epcot announced that they would be building a new pavilion in Future World East. It would be called Wonders of Life and be themed to health care . The pavilion would be located between Universe of Energy and Horizons . Wonders of Life would include new restaurants, stores and several attractions. One of these attractions would be

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6396-405: Is not the result of random thermal processes. Instead, the release of a photon is triggered by the nearby passage of another photon. This is called stimulated emission . For this process to work, the passing photon must be similar in energy, and thus wavelength, to the one that could be released by the atom or molecule, and the atom or molecule must be in the suitable excited state. The photon that

6519-501: Is the damping ratio, ω n {\displaystyle \omega _{n}} is the natural frequency of the cupula, and u ( t ) {\displaystyle u(t)} is the input angular acceleration. Values of ζ {\displaystyle \zeta } have been reported to be between 3.6 and 6.7 while values of ω n {\displaystyle \omega _{n}} have been reported to be between 0.75 and 1.9. Thus,

6642-514: Is then ready to make the next acceleration which will be detected by the subject, as in the real world. This so-called "acceleration onset cueing" is an important aspect in simulators with motion platforms and models the way humans feel motions in the real world. The vestibular system is the balance and equilibrium system of the body that includes the left and right vestibular organs of the "inner ear". It consists of three semicircular canals, or tubes, arranged at right angles to one another. Each canal

6765-489: Is to heat an object; some of the thermal energy being applied to the object will cause the molecules and electrons within the object to gain energy, which is then lost through thermal radiation , that we see as light. This is the process that causes a candle flame to give off light. Thermal radiation is a random process, and thus the photons emitted have a range of different wavelengths , travel in different directions, and are released at different times. The energy within

6888-504: Is to pump the laser material with a source that is itself pulsed, either through electronic charging in the case of flash lamps, or another laser that is already pulsed. Pulsed pumping was historically used with dye lasers where the inverted population lifetime of a dye molecule was so short that a high-energy, fast pump was needed. The way to overcome this problem was to charge up large capacitors which are then switched to discharge through flashlamps, producing an intense flash. Pulsed pumping

7011-441: Is typically expressed through the output being a narrow beam, which is diffraction-limited . Laser beams can be focused to very tiny spots, achieving a very high irradiance , or they can have a very low divergence to concentrate their power at a great distance. Temporal (or longitudinal) coherence implies a polarized wave at a single frequency, whose phase is correlated over a relatively great distance (the coherence length ) along

7134-430: Is used to measure the intensity profile, width, and divergence of laser beams. Diffuse reflection of a laser beam from a matte surface produces a speckle pattern with interesting properties. The mechanism of producing radiation in a laser relies on stimulated emission , where energy is extracted from a transition in an atom or molecule. This is a quantum phenomenon that was predicted by Albert Einstein , who derived

7257-550: Is used to orient the gravity vector 'g' of the simulator platform: β = sin − 1 ⁡ ( f g ) {\displaystyle \beta =\sin ^{-1}({\frac {f}{g}})} Typically, to find position, the low-pass filter (in a continuous-time setting) is represented in the s-domain with the following transfer function : L P ( s ) = 1 1 + s T {\displaystyle LP(s)={\frac {1}{1+sT}}} Laser A laser

7380-410: The phase of the emitted light is 90 degrees in lead of the stimulating light. This, combined with the filtering effect of the optical resonator gives laser light its characteristic coherence, and may give it uniform polarization and monochromaticity, depending on the resonator's design. The fundamental laser linewidth of light emitted from the lasing resonator can be orders of magnitude narrower than

7503-421: The transverse modes often approximated using Hermite – Gaussian or Laguerre -Gaussian functions. Some high-power lasers use a flat-topped profile known as a " tophat beam ". Unstable laser resonators (not used in most lasers) produce fractal-shaped beams. Specialized optical systems can produce more complex beam geometries, such as Bessel beams and optical vortexes . Near the "waist" (or focal region ) of

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7626-505: The "pencil beam" directly generated by a common helium–neon laser would spread out to a size of perhaps 500 kilometers when shone on the Moon (from the distance of the Earth). On the other hand, the light from a semiconductor laser typically exits the tiny crystal with a large divergence: up to 50°. However even such a divergent beam can be transformed into a similarly collimated beam employing

7749-677: The Quantum Theory of Radiation") via a re-derivation of Max Planck 's law of radiation, conceptually based upon probability coefficients ( Einstein coefficients ) for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation. In 1928, Rudolf W. Ladenburg confirmed the existence of the phenomena of stimulated emission and negative absorption. In 1939, Valentin A. Fabrikant predicted using stimulated emission to amplify "short" waves. In 1947, Willis E. Lamb and R.   C.   Retherford found apparent stimulated emission in hydrogen spectra and effected

7872-509: The Soviet Union, Nikolay Basov and Aleksandr Prokhorov were independently working on the quantum oscillator and solved the problem of continuous-output systems by using more than two energy levels. These gain media could release stimulated emissions between an excited state and a lower excited state, not the ground state, facilitating the maintenance of a population inversion . In 1955, Prokhorov and Basov suggested optical pumping of

7995-574: The USSR. The same studies suggest that the threshold is not a linear acceleration but rather a jerk motion (third time derivative of position), and the reported threshold value is on the order of 0.1 ft/s . These findings are supported by early studies showing that human movement kinematics is represented by characteristics of jerk profiles. Angular accelerations are detected by semicircular canals. The three semicircular canals are mutually orthogonal (similar to three-axis accelerometer) and are filled with

8118-494: The Wonders of Life pavilion. The popularity of Body Wars began to decline over the years. In 2004, the park announced that the attraction would begin seasonal operation. The entire pavilion would officially close on January 1, 2007. Guests entered the queue on the left side of the Wonders of Life Dome. If the attraction was in high demand, an extended queue would be utilized, decorated with signage and pastel colored shapes lining

8241-614: The acronym. It has been humorously noted that the acronym LOSER, for "light oscillation by stimulated emission of radiation", would have been more correct. With the widespread use of the original acronym as a common noun, optical amplifiers have come to be referred to as laser amplifiers . Modern physics describes light and other forms of electromagnetic radiation as the group behavior of fundamental particles known as photons . Photons are released and absorbed through electromagnetic interactions with other fundamental particles that carry electric charge . A common way to release photons

8364-466: The angle of the cupula θ {\displaystyle \theta } is given by θ ¨ + 2 ζ ω n θ ˙ + ω n θ = u ( t ) {\displaystyle {\ddot {\theta }}+2\zeta \omega _{n}{\dot {\theta }}+\omega _{n}\theta =u(t)} where ζ {\displaystyle \zeta }

8487-476: The beam. A beam produced by a thermal or other incoherent light source has an instantaneous amplitude and phase that vary randomly with respect to time and position, thus having a short coherence length. Lasers are characterized according to their wavelength in a vacuum . Most "single wavelength" lasers produce radiation in several modes with slightly different wavelengths. Although temporal coherence implies some degree of monochromaticity , some lasers emit

8610-425: The blue to near-UV have also been used in place of light-emitting diodes (LEDs) to excite fluorescence as a white light source; this permits a much smaller emitting area due to the much greater radiance of a laser and avoids the droop suffered by LEDs; such devices are already used in some car headlamps . The first device using amplification by stimulated emission operated at microwave frequencies, and

8733-730: The brain and oculomotor muscles. Studies indicate that the otoliths detect the tangential component of the applied forces. A transfer function model between the perceived force y ( s ) {\displaystyle y(s)} and the applied forces f ( s ) {\displaystyle f(s)} is given by: y ( s ) f ( s ) = 2.02 ( s + 0.1 ) s + 0.2 {\displaystyle {\frac {y(s)}{f(s)}}={\frac {2.02(s+0.1)}{s+0.2}}} Based on centrifuge experiments, threshold values of 0.0011 ft/s have been reported; values up to 0.4 ft/s have been reported based on airborne studies in

8856-407: The brain in proportion to accelerations to which the body is subject. An example of a "popular" proprioceptor mentioned by aircraft pilots, is the feeling in the "seat of the pants". Proprioceptors respond to stimuli generated by muscle movement and muscle tension. Signals generated by exteroceptors and proprioceptors are carried by sensory neurons or nerves and are called electrochemical signals. When

8979-455: The brain's energy to recharge the ship. Passing the heart's left atrium, the ship went through the artery to get to the brain. A neuron contacted the ship, allowing it to regain power and de-miniaturize outside of the subject's body. As the subject sits up, Mission Control congratulates Braddock, Lair, and the guests on pulling off the most spectacular mission in the history of MET. Used same ATLAS Technology as Star Tours . As of November 2014,

9102-440: The car are blindfolded. If the driver were to step on the gas, the car would accelerate forward thus pressing each passenger back into their seat. In this situation, each passenger would perceive the increase in speed by sensing the additional pressure from the seat cushion. Washout filters are an important aspect of the implementation of motion platforms as they allow motion systems, with their limited range of motion, to simulate

9225-406: The cues the brain receives by each of the body's sensory inputs must agree. It is physically impossible with most existing systems to correctly simulate large-scale motion in the limited space available in a simulator. The standard approach is to simulate cues of initial acceleration as closely as possible. In principle, velocity cannot be directly perceived by relative cues alone, like those from

9348-561: The effect of nonlinearity in optical materials (e.g. in second-harmonic generation , parametric down-conversion , optical parametric oscillators and the like). Unlike the giant pulse of a Q-switched laser, consecutive pulses from a mode-locked laser are phase-coherent; that is, the pulses (and not just their envelopes ) are identical and perfectly periodic. For this reason, and the extremely large peak powers attained by such short pulses, such lasers are invaluable in certain areas of research. Another method of achieving pulsed laser operation

9471-404: The filter is split into translation and rotational signals. High-pass filters are used for simulating transient translational and rotational accelerations, while the low-pass filters are used to simulate sustaining accelerations. The adaptive washout filter uses the classical washout filter scheme, but utilizes a self-tuning mechanism that is not featured with the classical washout filter. Finally,

9594-552: The first demonstration of stimulated emission. In 1950, Alfred Kastler (Nobel Prize for Physics 1966) proposed the method of optical pumping , which was experimentally demonstrated two years later by Brossel, Kastler, and Winter. In 1951, Joseph Weber submitted a paper on using stimulated emissions to make a microwave amplifier to the June 1952 Institute of Radio Engineers Vacuum Tube Research Conference in Ottawa , Ontario, Canada. After this presentation, RCA asked Weber to give

9717-517: The four simulators have been dismantled and removed from the ride building. The queue is still intact, but most of the lighting and electronic equipment has been removed. The show building is currently used for storage for the Epcot Food & Wine Festival , along with the Flower & Garden Festival. As of November 2016, the queue is being slowly dismantled while few remnants remain. The pavilion

9840-470: The high end, plus some of the more expensive amusement park rides that use a simulator-type motion base; arcade amusement devices are in the middle, and motion platforms for home use are low-cost but not as capable of the higher-level devices. Many motion platforms are used in flight simulators used to train pilots. One of the first motion platforms, the Sanders Teacher, was created in 1910. This

9963-424: The inputs are expressed in the vehicle-body-fixed frame. Since low-frequency force is dominant in driving the motion base, force is high-pass filtered, and yields the simulator translations. Much the same operation is done for angular rate. To identify the tilt of the motion platform, the tilt mechanism first supplies the low-frequency component of force for rotation calculation. Then, the high-frequency component 'f'

10086-422: The laser power inside the cavity; this equilibrium determines the operating point of the laser. If the applied pump power is too small, the gain will never be sufficient to overcome the cavity losses, and laser light will not be produced. The minimum pump power needed to begin laser action is called the lasing threshold . The gain medium will amplify any photons passing through it, regardless of direction; but only

10209-501: The lasing medium or pumping mechanism, then it is still classified as a "modulated" or "pulsed" continuous wave laser. Most laser diodes used in communication systems fall into that category. Some applications of lasers depend on a beam whose output power is constant over time. Such a laser is known as a continuous-wave ( CW ) laser. Many types of lasers can be made to operate in continuous-wave mode to satisfy such an application. Many of these lasers lase in several longitudinal modes at

10332-414: The latter case, the photon is emitted in the same direction as the light that is passing by. When the number of particles in one excited state exceeds the number of particles in some lower-energy state, population inversion is achieved. In this state, the rate of stimulated emission is larger than the rate of absorption of light in the medium, and therefore the light is amplified. A system with this property

10455-432: The limited space of a laboratory. The standard approach to simulating motion (so called motion cueing) is to simulate the “relevant” cues as closely as possible which trigger motion perception . These cues can be visual, auditory, or somatosensory in nature. Visual and auditory cues enable humans to perceive their location in space on an absolute scale, whereas somatosensory cues (mainly proprioception and other signals from

10578-509: The linewidth of light emitted from the passive resonator. Some lasers use a separate injection seeder to start the process off with a beam that is already highly coherent. This can produce beams with a narrower spectrum than would otherwise be possible. In 1963, Roy J. Glauber showed that coherent states are formed from combinations of photon number states, for which he was awarded the Nobel Prize in physics . A coherent beam of light

10701-402: The literal cavity that would be employed at microwave frequencies in a maser . The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in

10824-522: The lower level, emitting a new photon. The emitted photon exactly matches the original photon in wavelength, phase, and direction. This process is called stimulated emission. The gain medium is put into an excited state by an external source of energy. In most lasers, this medium consists of a population of atoms that have been excited into such a state using an outside light source, or an electrical field that supplies energy for atoms to absorb and be transformed into their excited states. The gain medium of

10947-412: The maximum possible level, the introduced loss mechanism (often an electro- or acousto-optical element) is rapidly removed (or that occurs by itself in a passive device), allowing lasing to begin which rapidly obtains the stored energy in the gain medium. This results in a short pulse incorporating that energy, and thus a high peak power. A mode-locked laser is capable of emitting extremely short pulses on

11070-498: The medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially . But each stimulated emission event returns an atom from its excited state to the ground state, reducing the gain of the medium. With increasing beam power, the net gain (gain minus loss) reduces to unity and the gain medium is said to be saturated. In a continuous wave (CW) laser, the balance of pump power against gain saturation and cavity losses produces an equilibrium value of

11193-452: The most sophisticated motion simulator cabinets in arcades was Sega's R360 (1990), which simulated the full 360-degree rotation of an aircraft. Sega have since continued to manufacture motion simulator cabinets for arcade games through to the 2010s. The lower-cost systems include home-based motion platforms, which have recently become a more common device used to enhance video games, simulation, and virtual reality. These systems fall into

11316-439: The need to construct expensive prototypes. For example, an engineer designing an external fuel tank for an aircraft could have a pilot determine the effect on flying qualities or a mechanical engineer could feel the effects of a new brake system without building any hardware, saving time and money. Flight simulators are also used by aircraft manufacturers to test new hardware. By connecting a simulated cockpit with visual screen to

11439-445: The next acceleration to be produced by the motion platform and sensed by the subject of the simulator. The human eye is an important source of information in motion simulation where a high resolution picture is available such as by day in good visibility. The eye relays information to the brain about the craft's position, velocity, and attitude relative to the ground. As a result, it is essential for realistic simulation that cues from

11562-404: The object is not random, however: it is stored by atoms and molecules in " excited states ", which release photons with distinct wavelengths. This gives rise to the science of spectroscopy , which allows materials to be determined through the specific wavelengths that they emit. The underlying physical process creating photons in a laser is the same as in thermal radiation, but the actual emission

11685-403: The optimal washout filter takes into account models for vestibular system. The classical washout filter is simply a combination of high-pass and low-pass filters ; thus, the implementation of the filter is compatibly easy. However, the parameters of these filters have to be empirically determined. The inputs to the classical washout filter are vehicle-specific forces and angular rate. Both of

11808-479: The order of 10 – 20 seconds, the hair follicles return to the “zero” or vertical position and the brain interprets this as the acceleration ceasing. Additionally, there is a lower acceleration threshold of about 2 degrees per second that the brain cannot perceive. In other words, slow motion below the threshold will not generate vestibular cues. As discussed in the preceding “Proprioceptors” section, this allows simulator motion to be "washed out" below threshold, ready for

11931-456: The order of tens of picoseconds down to less than 10  femtoseconds . These pulses repeat at the round-trip time, that is, the time that it takes light to complete one round trip between the mirrors comprising the resonator. Due to the Fourier limit (also known as energy–time uncertainty ), a pulse of such short temporal length has a spectrum spread over a considerable bandwidth. Thus such

12054-432: The other senses of vision, touch and sound, the vestibular input is registered quickly by the brain, whereas visual changes such as perspective and horizon movement, follow shortly after. Therefore, in a simulator it is essential that visual cues are not perceived before motion cues, the reverse of the real-world situation, or so-called "simulator sickness" can occur. Second, if the head experiences sustained accelerations on

12177-543: The perceived angular displacement y ( s ) {\displaystyle y(s)} and the actual angular displacement p h i ( s ) {\displaystyle phi(s)} is: y ( s ) p h i ( s ) = 0.07 s 3 ( s + 50 ) ( s + 0.05 ) ( s + 0.03 ) {\displaystyle {\frac {y(s)}{phi(s)}}={\frac {0.07s^{3}(s+50)}{(s+0.05)(s+0.03)}}} A second-order model of

12300-418: The photons in a spatial mode supported by the resonator will pass more than once through the medium and receive substantial amplification. In most lasers, lasing begins with spontaneous emission into the lasing mode. This initial light is then amplified by stimulated emission in the gain medium. Stimulated emission produces light that matches the input signal in direction, wavelength, and polarization, whereas

12423-481: The pilot's control stick and rudder controls to control organ-type bellows under the simulator cockpit. The bellows could inflate or deflate, giving movement in pitch, roll, and yaw. In 1958 a flight simulator for the Comet 4 aircraft used a three-degrees-of-freedom hydraulic system. Simulator motion platforms today use 6 jacks ("Hexapods") giving all six degrees-of-freedom, the three rotations pitch, roll and yaw, plus

12546-405: The pilots responds to accelerations that occur in full-motion simulators and aircraft, but not in fixed simulators. This effect shows that there is a potential negative training transfer when transitioning from a fixed-based simulator to an aircraft and indicates the need for motion systems for full-fidelity pilot training. It is physically impossible to precisely simulate large scale real motion in

12669-549: The platform under the simulator cab. A typical high-end motion system is the Stewart platform , which provides full 6 degrees of freedom (3 translation and 3 rotation) and employs sophisticated algorithms to provide high-fidelity motions and accelerations. These are used in a number of applications, including flight simulators for training pilots. The middle of the spectrum includes motion platforms in arcade amusement games , rides, and other arrangements. These systems fall into

12792-404: The player full-body tactile feedback. Motion gaming chairs can roll to the left and right and pitch forward and backward to simulate turning corners, accelerations and decelerations. Motion platforms permit a more stimulative and potentially realistic gaming experience, and allow for even greater physical correlation to sight and sound in game play. The way we perceive our body and our surroundings

12915-409: The power output is essentially continuous over time or whether its output takes the form of pulses of light on one or another time scale. Of course, even a laser whose output is normally continuous can be intentionally turned on and off at some rate to create pulses of light. When the modulation rate is on time scales much slower than the cavity lifetime and the period over which energy can be stored in

13038-662: The properties of the emitted light, such as the polarization, wavelength, and shape of the beam. Electrons and how they interact with electromagnetic fields are important in our understanding of chemistry and physics . In the classical view , the energy of an electron orbiting an atomic nucleus is larger for orbits further from the nucleus of an atom . However, quantum mechanical effects force electrons to take on discrete positions in orbitals . Thus, electrons are found in specific energy levels of an atom, two of which are shown below: An electron in an atom can absorb energy from light ( photons ) or heat ( phonons ) only if there

13161-451: The range of vehicle dynamics being simulated. Since the human vestibular system automatically re-centers itself during steady motions, washout filters are used to suppress unnecessary low-frequency signals while returning the simulator back to a neutral position at accelerations below the threshold of human perception. For example, a pilot in a motion simulator may execute a steady, level turn for an extended period of time which would require

13284-457: The relationship between the A coefficient , describing spontaneous emission, and the B coefficient which applies to absorption and stimulated emission. In the case of the free electron laser , atomic energy levels are not involved; it appears that the operation of this rather exotic device can be explained without reference to quantum mechanics . A laser can be classified as operating in either continuous or pulsed mode, depending on whether

13407-411: The ride. What will happen to Body Wars during the transformation is currently unknown. Motion simulator Motion simulators can be classified according to whether the occupant is controlling the vehicle(such as in a Flight Simulator for training pilots), or whether the occupant is a passive rider , such as in a simulator ride or motion theater. Motion platforms for aircraft simulators are at

13530-404: The same magnitude and at the same rate. Simultaneously, the cab tilts the occupant to imitate the motion. The occupant's proprioceptors and vestibular system sense this motion. The motion and change in the visual inputs must align well enough such that any discrepancy is below the occupant's threshold to detect the differences in motion. In order to be an effective training or entertainment device,

13653-410: The same time, and beats between the slightly different optical frequencies of those oscillations will produce amplitude variations on time scales shorter than the round-trip time (the reciprocal of the frequency spacing between modes), typically a few nanoseconds or less. In most cases, these lasers are still termed "continuous-wave" as their output power is steady when averaged over longer periods, with

13776-481: The skin and chemical substances that stimulate the nose and mouth. Internal receptors (enteroceptors) respond to stimuli that arise from within blood vessels. Postural stability is maintained through the vestibular reflexes acting on the neck and limbs. These reflexes, which are key to successful motion synchronization, are under the control of three classes of sensory input: Proprioceptors are receptors located in muscles, tendons, joints and gut, which send signals to

13899-610: The subject backwards and use the gravity vector as a replacement for correct resulting force from gravity and forward acceleration. In this case, leaning a simulator backwards and rotating the visual picture by the same angle gives the subject a force on the back that is perceived as forward acceleration. Linear accelerations are detected by otoliths. The otolith structure is simpler than the three-axis semicircular canals that detect angular accelerations. The otoliths contain calcium carbonate particles that lag behind head movement, deflecting hair cells. These cells transmit motion information to

14022-406: The system is overdamped with distinct, real roots. The shorter time constant is 0.1 seconds, while the longer time constant depends on the axis about which the test subject is accelerating (roll, pitch, or yaw). These time constants are one to two orders of magnitude greater than the shorter time constant. Experiments have shown that angular accelerations below a certain level cannot be detected by

14145-549: The system stay at the associated bank angle, but a washout filter allows the system to slowly move back to an equilibrium position at a rate below the threshold which the pilot can detect. This allows the higher level dynamics of the computed vehicle to provide realistic cues for human perception, while remaining within the limitations of the simulator. Three common types of washout filters include classical, adaptive and optimal washout filters. The classical washout filter comprises linear low-pass and high-pass filters. The signal into

14268-614: The three translational movements heave (up and down), sway (sideways) and surge (longitudinal). 6 Dof motions are powerful cues when combined with outside-world (OTW) imagery. Motion platforms together with OTW imagery are used in : flight simulation, driving simulation, amusement rides, and small home-based simulators. The motion platform is used in military and commercial flight instruction training applications. Also in entertainment devices in theme parks, with users from single people to many, seated in rows in front of screens in which pictures are projected, synchronised with motions from

14391-425: The two mirrors, the output coupler , is partially transparent. Some of the light escapes through this mirror. Depending on the design of the cavity (whether the mirrors are flat or curved ), the light coming out of the laser may spread out or form a narrow beam . In analogy to electronic oscillators , this device is sometimes called a laser oscillator . Most practical lasers contain additional elements that affect

14514-410: The very high-frequency power variations having little or no impact on the intended application. (However, the term is not applied to mode-locked lasers, where the intention is to create very short pulses at the rate of the round-trip time.) For continuous-wave operation, the population inversion of the gain medium needs to be continually replenished by a steady pump source. In some lasing media, this

14637-440: The vestibular system) provide only feedback of accelerations. For example, consider riding in a car traveling at some arbitrary constant speed. In this situation, our sense of sight and sound provide the only cues (excluding engine vibration) that the car is moving; no other forces act on the passengers of the car except for gravity. Next, consider the same example of a car moving at constant speed except this time, all passengers of

14760-407: The vestibular system. For such a system, flying in space with some constant velocity is not different from sitting in a chair. However, changing the velocity is perceived as acceleration, or force acting on the human body. For the case of constant linear acceleration, a substitute for the real situation is simple. Since the amplitude of the acceleration is not very well perceived by humans, one can tilt

14883-418: The walls. This would lead into the main queue, contained within a separate external wing of the building. As guests entered, they were informed via in-queue announcements of details surrounding the fictional MET company. The guests were referred to as "MET Observation Team Members", and would be informed via a preshow shown within the queue of the mission that they would be going on, with another volunteer who had

15006-450: Was a model aircraft connected to the ground by a universal joint. When wind was present, the pilot in training was able to use the aircraft's control surfaces to move the model in the three rotational degrees of freedom pitch, roll and yaw. In 1929 a significant advance in motion platform technology was made with the patent by Edwin Link for what became known as the "Link Trainer". This used

15129-598: Was called a maser , for "microwave amplification by stimulated emission of radiation". When similar optical devices were developed they were first called optical masers , until "microwave" was replaced by "light" in the acronym, to become laser . Today, all such devices operating at frequencies higher than microwaves (approximately above 300 GHz ) are called lasers (e.g. infrared lasers , ultraviolet lasers , X-ray lasers , gamma-ray lasers ), whereas devices operating at microwave or lower radio frequencies are called masers. The back-formed verb " to lase "

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