US2623165A - Modulated light communication system - Google Patents

Modulated light communication system Download PDF

Info

Publication number
US2623165A
US2623165A US1002A US100248A US2623165A US 2623165 A US2623165 A US 2623165A US 1002 A US1002 A US 1002A US 100248 A US100248 A US 100248A US 2623165 A US2623165 A US 2623165A
Authority
US
United States
Prior art keywords
medium
light
vibrations
wavelength
waves
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US1002A
Other languages
English (en)
Inventor
Mueller Hans
Robert H Rines
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE552939D priority Critical patent/BE552939A/xx
Application filed by Individual filed Critical Individual
Priority to US1002A priority patent/US2623165A/en
Application granted granted Critical
Publication of US2623165A publication Critical patent/US2623165A/en
Priority claimed from GB3381956A external-priority patent/GB823801A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0128—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects
    • G02F1/0131—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/11—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/532—Polarisation modulation

Definitions

  • the present invention relates to communication. and more particularly to the transmission and reception of signal intelligence.
  • An object of the invention is to provide a new and improved system for secret signaling.
  • Another object is to provide a new and improved system for communication employing light modulation.
  • a further object is to provide a new and improved system for transmitting.
  • a further object still is to provide a new and improved system for receiving.
  • Still another object is to provide a new improved system for transmitting and receiving.
  • a further object of the invention is to provide a new and improved system employing the lightmodulation principles described in the said copending application.
  • Fig. 1 is a diagrammatic view of circuits and apparatus illustrating the ultrasonic lightmodulation method and system disclosed in the said application
  • Fig. 2 is an explanatory diagram
  • Fig. 3 is a reproduction of a photograph obtained by employing the light-modulation system of Fig. 1, illustrating the efiect produced upon a polarized beam or bundle of light in response to longitudinal compressional ultrasound waves imparted to a transparent solid medium through which the beam or bundle is passed
  • Fig. 4 is a reproduction of a similar photograph illustrating the effect of transverse shearing ultrasound waves, the light beam, however, being of different polarization
  • Fig. 1 is a diagrammatic view of circuits and apparatus illustrating the ultrasonic lightmodulation method and system disclosed in the said application
  • Fig. 2 is an explanatory diagram
  • Fig. 3 is a reproduction of a photograph obtained by employing the light-modulation system of Fig. 1, illustrating the efiect produced upon a polarized beam or bundle of light in
  • FIG. 5 is a reproduction of a similar photograph illustrating the effect produced by employing a medium the transverse dimension of which is comparable to the wavelength of the ultrasound waves in the medium;
  • Fig. 6 is a diagrammatic view, similar to Fig. l, of a transmitting system constructed in accordance with a preferred embodiment of the present invention;
  • Fig. 7 is a similar view of a receiving system;
  • Fig. 8 is a view similar to Fig. 6 of a modified transmitting system;
  • Fig. 9 is 2 similarly a view similar to Fig. 7 of a modified receiving system.
  • a light source I such, for example, as a mercury arc
  • a light source I such, for example, as a mercury arc
  • the present invention is not however restricted to use with visible light. On the contrary. it has particular use in connection with infra-red rays.
  • An infra-red or even an ultra-violet filter 3 may. therefore, if desired. be employed.
  • a filter 3, adapted to produce monochromatic visible light of any desired wavelength may also be employed. though the invention is operable with chromatic as well as monochromatic light.
  • the light waves are shown collimated by a lens 5 into a parallel beam or bundle of rays of crossdimension corresponding to the cross-dimension of the lens 5.
  • the beam or bundle of light rays is caused to pass through a plane polarizer I such. for example, as a Nicol prism or a piece of polaroid, and thereafter to impinge upon a substantial area of the front surface 9 of a medium I3.
  • the medium I3. should be transparent to the light rays employed, whether visible, infrared or ultraviolet, along the direction of travel of the light through the medium l3 between the front surface 9 and the preferably parallel rear surface II.
  • the transparent medium I3 is preferably of the same cross-dimension as the crossdimension of the light beam.
  • the rear surface H of the transparent medium I3 is shown separated from the front surface 9 by a thickness T.
  • the transparent medium I3 may be constituted of a glass or non-crystalline fused quartz block, or any other transparent solid or liquid. It may or may not be piezoelectric. For the present, it will be assumed. in the further description. that it is not piezoelectric but, on the contrary, that it is optically inactive, birefringent-free. and strain-free.
  • the medium l3 may be vibrated molecularly in any desired way.
  • the vibrations are produced by means of an ultrasonic vibrator.
  • the vibrator may be constituted of a piezoelectric crystal l5. as of quartz. but it may also be of the magnetostrictive. magnetomotive or of any other suitable type.
  • the quartz crystal l5 may be vibrated at a predetermined frequency by connecting its two electrodes ll and I! to an oscillator 2 l.
  • period of vibration of the crystal I5 may be relatively low, say, several hundred kilocycles, more or less, or as high as ten megacycles, more or less.
  • the ultrasonic vibrations of the quartz crystal l5 adiacent, for example, the bottom edge of the medium, will therefore become transmitted or directed into the medium l3 toward the top edge.
  • the medium i3 may be held in place on the crystal IS in any desired way, as by cement or even by a layer of oil to aid in this transmission or direction.
  • the quartz crystal vibrates along its thickness dimension, so that it alternately elongates and contracts vertically.
  • the height dimension of the medium I3 is equal to a whole multiple of the wavelength of the ultrasound waves in the medium, standing waves of ultrasonic frequency. as before stated, will theoretically be set up in the medium between its bottom and top edge surfaces. It is assumed that the medium I3 is of such a nature that. when it is vibrated molecularly to produce these theoretical standing waves therein, it becomes birefringent to the light passing therethrough along the direction of travel of the light through the medium which is substantially perpendicular to the direction of the ultrasound waves between the bottom and top edges.
  • the cross-dimension of the parallel beam or bundle of the plane-polarized light rays impinging upon the front surface 9 of the medium l3 corresponds to the cross-dimension of the lens 5, it is large compared to the dimension of the standing waves produced in the medium 13. This is to be contrasted with the conditions obtaining in the prior-art diffraction methods and in the systems employing frequency sensitive crystalline media or shaped media, as discussed in the said copending application.
  • this large parallel beam or bundle of polarized light is shown in Fig. 1 focused by a lens 23 upon a screen 21.
  • the lens 23 and the screen 21, of course, may be replaced by some other optical system, such as an ocular, a camera, a photocell 22, or any other suitable system for receiving and indicating the beam of light from the rear surface I I of the medium 13.
  • An analyzer 25 is shown interposed between the lens 23 and the screen 21. It may be constituted of a piece of polarizing material oriented at right angles to the orientation of the polarizer I. Under normal conditions, therefore, when the circuit of the oscillator 2! is open, and the crystal l5, therefore, is not vibrating, the polarized light passing through the medium I3 will be extinguished by the analyzer 25, to a degree depending only on the effectiveness of the polarizing and analyzing materials, with the result that the screen 21 will be dark.
  • phase shifts may respectively be represented by where r is the ratio of the circumference to the diameter of a circle.
  • optically active crystals This operation is therefore not the same as that occurring with optically active crystals or other crystalline substances as before described.
  • the operation occurring with the optically active crystals depends upon rotating the plane of plane polarization.
  • the operation occurring with permanently doubly retracting crystalline substances depends upon modifying the amount of double refraction.
  • the operation of the present invention depends upon depolarizing plane-polarized waves into elliptically polarized waves.
  • the analyzer 25 may be so oriented that, when no ultrasonic vibrations whatever are propagated into the medium l3, the screen 21 is dark.
  • the oscillator 2! causes the crystal to set up standing ultrasonic waves in the medium I3, on the other hand, bright layers, striations, bands, regions or stripes 2 will appear on the screen 21. The layers, striations. bands, regions or stripes 4 between alternately disposed light layers 2 will remain dark.
  • the dark stripes will correspond to the light passing through the nonvibrating or nodal portions of the medium IS.
  • the light stripes 2 will correspond to the successive portions of the light beam which have become elliptically polarized during passage through the corresponding compressed and dilated portions or sections of the medium l3.
  • the analyzer 25 may be so oriented that, under normal conditions, when the medium is not vibrating, the screen 21 shall just be illuminated.
  • the compressed and dilated sections of the medium I 3, produced in response to the vibration of the medium l3, may periodically produce elliptically polarized light, the major axis of which is normal to the orientation of the analyzer 25, so that most of the light passing through these sections, when they produce such elliptically polarized light, is extinguished.
  • the light stripes 2 will then correspond to the nodes, and alternately disposed dark stripes 4 to the compressed and dilated sections of the medium 13, produced in response to the vibration of the medium 13.
  • the analyzer 25 may be adjusted initially so as normally either to extinguish the polarized light after its passage through the medium l3, or to permit the light to pass onto the screen 21.
  • the analyzer 25 may be adjusted to a degree such as initially to produce extinction and such that a slight change in the analyzing process in one direction, resulting from the action of the birefringent medium I3 to change the state of polarization of the light, will provide bands or sections 2 of illumination alternately with dark bands or sections upon the screen 21.
  • the analyzer 25 may, on the other hand, be adjusted to a degree such as initially almost, but not quite, to extinguish the analyzed light on the screen 21 and such that an equal change in the analyzing process in the opposite direction, resulting from the action of the birefringent medium on the light will produce dark bands or sections alternately with light sections 2 on the screen 21.
  • the phenomenon in reality, is produced stroboscopically. Because the frequency of the ultrasonic waves is many times greater than that of the flicker limit of the eye. however, the effect upon the observer will be the same as though the light layers 2 were produced with the aid of continuous light issuin from the analyzer 25.
  • the difference (mu-(1m) in the changes of the index of refraction along the vertical and horizontal directions is known as the birefringence of the medium. It is proportional to the total phase shift suffered by the light in passing through the compressed and dilated sections of the medium l3.
  • the intensity of illumination of the light stripes 2 is proportional to the square of the sine of half the phase shift b sufiered in passing through the medium I3.
  • the operation above described has been upon the assumption that the height dimension of the medium I3 is equal to a whole multiple of the wavelength of the ultrasonic waves propagated through the medium between its bottom and top surfaces. This, however, was for explanatory purposes only. It has been found that, particularly at the higher frequencies. a medium of any arbitrary dimension may be employed, irrespective of whether or not it is a multiple of the wavelength. provided only that it is large with respect to the wavelength of the ultrasound waves. It has also been found that such a photoelastic-shutter system is not frequency-sensitive, and the dimensions need bear no specific rela-- tionship to the wavelength of the ultrasound waves.
  • the flat area of the crystal I5 is shown. in Fig. l, as substantially equal to the cross-sectional area of the medium I3 into which it propagates the ultrasound waves, this is not essential.
  • the medium I3 may have a cross-dimension many times the area of the crystal l5, though the birefringence effect resulting from the ultrasound waves will then not be produced strongly throughout the whole medium.
  • a plurality of vibrators as shown in Fig. 8, may be employed in contact with successive portions of the medium l3.
  • a single large flat area crystal may also be used. No slits or stops are necessary.
  • the light issuing from the polarizer 1 may be polarized at any other desired angle.
  • the effect of vertical polarization may be studied by considering the change of the refractive index resulting from the shearing strain produced in the medium It by its transverse vibrations as decomposed along two directions at right angles to each other along the plane of the surface 9.
  • One of these may be an angle of 45 degrees with respect to the vertical, as may also be indicated at P, Fig. 2, and the other may be indicated at P.
  • the components of the vertically-polarized waves along the 45-degree directions P and P, during their passage through the medium [3, will sufier diiferent phase shifts, depending on the changes in the refractive index along the two directions P and P.
  • the distances between the centers of the successively disposed light or dark striations or layers are respectively equal to one-half the wavelength A1 of the longitudinal compressional vibrations and one-half the wavelength M of the transverse compressional vibrations propagated vertically and horizontally, respectively, in the medium 13.
  • the values of these wavelengths obtained by measurement may be used directly to find Young's modulus e and Poissons ratio 0'.
  • the wavelength A: of the longitudinal waves in the vertical direction was found to be 0.532 millimeter and the wavelength M of the transverse waves was found to be 0.312 millimeter.
  • Young's modulus e was then calculated to be '7.t5 10 degrees/cm. from the formula 1-0 This value agrees with the values obtained for the same sample [3 by diffraction methods.
  • the invention has heretofore been explained in connection with birefringent-free and strainfree media l3. It is preferable to employ media [3 of this character, and to adjust the analyzer 25 so as to obtain complete extinction before the vibrations are initiated in the medium. Extremely intense stroboscopic-light layers have thus been observed, for example, with noncrystalline fused-quartz media.
  • Chrystalline substances having permanent birefringence may also theoretically be employed. They also demonstrate light-intensity changes when subjected to ultrasonic waves, as described above. If an optically active medium 43. such as a piezo-electn'c crystal. is used. however, then. in order to detect the effect of the birefringence on the light emerging from the face I l of the medium. it is necessary to orient the analyzer 25 at right angles to the polarizer, and not so as to extinguish the light emerging from the medium, the plane of polarization of which has been rotated in passing through the medium. It is then only that the birefringence effect, in addition to the optical activity, may theoretically be detected. In practice. the much stronger effect of the change in optical activity produced by straining the medium may prevent the detection of the effects of birefringence.
  • an optically active medium 43 such as a piezo-electn'c crystal.
  • each polarizing device 1 and 25 If a quarter-wave plate is inserted in front of each polarizing device 1 and 25, so that circularlypolarized. instead of plane-polarized, light is impinged upon the medium l3, and is analyzed after emerging therefrom, even stronger-intensity results occur. While some of the intensity resulting from the birefringence produced by the longitudinal waves is lost. this is apparently more than made up for by the light intensity resulting from the birefringence produced by the transverse waves. Waves having initially elliptical polarization may also be employed.
  • Continous-wave signals may be transmitted by the system of Fig. l or of Fig. 6 in many ways, as by interrupting the circuit of the oscillator 2
  • Modulated audio or video signals may be transmitted by modulating the carrier frequency of the oscillator 2
  • the non-resonant, relatively largedimensioned medium [3 has been found to respond sufiiciently instantaneously to the modulated ultrasonic carrier, propagated thereinto from the crystal IE. to produce birefringence in response to the modulation signal.
  • the lens 23 may therefore be caused to focus the birefringenceproduced elliptically-polarized light from the medium l3 on to some other light-receiving means than the screen 21.
  • a photocell 22 may be employed to receive elliptically polarized light.
  • the photocell 22 may be connected to an audio or video amplifier 28.
  • Crystalline media I may also be used for the photocell or photographic detection of this lightmodulation transmission, though with limitations of frequency sensitiveness, and accompanied by background noise or light.
  • the photocell 22 is itself sensitive to only a band of wavelengths. By designing it so that it shall respond with maximum effect to light having the wavelength of infrared or other monochromatic rays, most sensitive and most noiseless operation may then be obtained with monochromatic light of such wavelength.
  • the transmission may be effected by feeding one or more of the modulating signals to the same quartz or other ultrasonic vibrator 15. Such procedure tends, however, to overload the mechanical parts of the system.
  • the multi channels may also be obtained by employing a plurality of vibrators l5 and I5, as shown in Fig. 8, in sonic contact with the medium, and modulating the vibrators with different signals from the modulators 20 and 20. If the different modulations are of entirely different frequency ranges, such as correspond, for example. to an audio modulation and a video modulation, there will be very little distortion when received in the receiving system of Fig.
  • the photocell may feed tuned amplifiers. such as the amplifiers 2B and 28' which will separate out and amplify the intelligence of the different channels; for example, the amplifier 28 may separate out and amplify the audio channel while the amplifier 28' amplifies the video channel.
  • tuned amplifiers such as the amplifiers 2B and 28' which will separate out and amplify the intelligence of the different channels; for example, the amplifier 28 may separate out and amplify the audio channel while the amplifier 28' amplifies the video channel.
  • Audio frequencies ranging from 40 cycles to 15,000 cycles have been used to modulate a ten-megacycle ultrasonic carrier with noiseless and distortionless results.
  • this light-modulation system it is desirable: first. properly to orient the plane of polarization of the polarizer; secondly, to control the operation of the piezo-electric carrier on and off the resonant frequency of the -piezo-electric crystal; thirdly; to position the medium l3 so as to intercept more or less of the incident light; and fourthly, suitably to insert or remove a diaphragm, or to control the aperture of a diaphragm in the path of the light beam.
  • the analyzer 25 may be provided with suitable phase-shifting plates.
  • the elliptically polarized waves emerging from the compressed and dilated regions of the medium l3 will thus be properly analyzed, whil permitting the plane-polarized light passing through the nodal-region portions of the medium to penetrate the analyzer 25.
  • the use of a quarter-wave plate with the analyzer 25 may be particularly desirable, for example, where the thickness T of the medium is such as to produce exactly a ninety-degree phase shift between the components V and H of the incident light, circularly polarizing the light emerging from the compressed and dilated regions.
  • a communication system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through the medium along the predetermined direction a bundle of light of cross-dimension large compared to the wavelength of the standing waves, a polarizer for polarizing the light prior to its pas sage through the medium, an analyzer for analyzing the light after its passage through the medium, the analyzer being adjusted so that a change in the analyzing produced thereby in one direction will provide extinction of the analyzed light and a substantially equal change in the analyzing produced thereby in the opposite direction will permit the passage of the analyzed light, means for roducing molecular vibrations of the said predetermined wavelength at one of the said edges of the
  • Apparatus as set forth in claim 1 all of the dimensions of the medium of which are large 12 compared to the wave-length of the standing waves.
  • a communication system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through the medium along the predetermined direction a bundle of light of cross-dimension large compared to the wavelength of the standing waves, a polarizer for polarizing the light prior to its passage through the medium, an analyzer for extinguishing the light after its passage through the medium, means for producing molecular vibrations of th said predetermined wavelength at one of the said edges of the medium. means for directing the vibrations into the medium toward the other said edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves. means for modulating the molecular vibrations, and means for receiving the analyzed
  • Apparatus as set forth in claim 5 the vibrating means of which comprises means for pr pagating ultrasonic waves into the medium.
  • a communication system having, in comination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to th light passing therethrough along the predetermined direction, means for passing through the medium along the predetermined direction a bundle of light of cross-dimension large compared to the wavelength of the standing waves, a polarizer for polarizing the light prior to its passage through the medium, an analyzer for extinguishing the light after its passage through the medium, means for producing molecular vibrations of the said predetermined wavelength at one of the said edges of the medium, means for directing the vibrations into the medium toward the other said edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves.
  • a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined ultrasonic wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through u u i.- HUM-m 13 the medium along the predetermined direction a bundle of light of cross-dimension large compared to the wavelength of the standing waves, a polarizer for polarizing the light prior to its passag through the medium, an analyzer for analyzing the light after its passage through the medium, the analyzer being adjusted so that the analyzed light is almost but not quite extinguished, means for producing molecular vibrations of the said predetermined wavelength at one of the said edges of the medium, means for directing the vibrations into the medium toward the other said edge of the
  • a transmitter having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times th said wavelength, becomes birefringent to light passing therethrough along the predetermined direction, means for passing light through the medium along the predetermined direction, a polarizer for polarizing th light prior to its passage through the medium, means for producing molecular vibrations of the said predetermined wavelength at one of the said dges of the medium, means for directing the vibrations into the medium toward the other said edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves, and means for modulating the molecular vibrations of the medium.
  • a communication system having, in combination, a medium having front and rear surfaces and that is transparent to light along the direction between the front and rear surfaces,
  • the medium being normally birefringent-free to light propagated along the said direction, means for passing a bundle of light toward a substantial area of the front surface, a polarizer interposed in the path of the light, an analyzer positioned in the path of the light emerging from the rear surface after its passage through the medium, means for producing ultrasonic vibrations at an edge of the medium of wavelength small compared with the distance between the said edge and a second edge of the medium, means for directing the vibrations into the medium toward the said second edge in order that the vibrations may be reflected therefrom to set up standing waves that render th medium birefringent to the light, means for modulating the molecular vibrations with an audio signal, and means positioned beyond the analyzer for rendering th signal detectable.
  • a communication system having, in combination, a medium having front and rear surfaces and that is transparent to light, means for passing a bundle of light toward a substantial area of the front surface, a plane polarizer interposed in the path of the light and oriented along a dimension of the medium, an analyzer positioned in the path of the light emerging from the rear surface after its passage through the medium and oriented at right angles to the polarizer, means for producing carrier-wave vibrations at an edge of the medium of wavelength small compared with the distance between the said edge and a second edge of the medium from which the Vibrations may be reflected, means for modulating the amplitude of the said carrier-wave vibrations, and means positioned beyond the analyzer for rendering the modulations detectable.
  • a communication system having, in combination, a medium having front and rear surfaces and that is transparent to light, means for passing a bundle of light toward a substantial area of the front surface, a plane polarizer interposed in the path of the light and oriented at forty-five degrees to a dimension of the medium.
  • an analyzer positioned in the path of the light emerging from the rear surface after its passage through the medium and oriented at right angles to the polarizer, means for producing carrierwave vibrations at an edge of the medium of wavelength small compared with the distance between the said edge and a second edge of the medium from which the vibrations may be reflected, means for modulating the amplitude of the said carrier-wave vibrations, and means positioned beyond the analyzer for rendering the modulations detectable.
  • a communication system having, in combination, a medium having front and rear surfaces and that is transparent to light, means for passing a bundle of light toward a substantial area of the front surface, means interposed in the path of the bundle of light for circularly polarizing the light, means positioned in the path of the light emerging from the rear surface after its passage through the medium for analyzing the light, means for producing carrier-wave vibrations at an edge of the medium of wavelength small compared with the distance between the said edge and a second edge of the medium from which the vibrations may be reflected, means for varying a property of the wave, and means positioned beyond the analyzer for rendering the variation detectable.
  • a communication system having, in combination, a medium having substantially parallel front and rear surfaces, that is transparent to light. and that is of a predetermined refractive index, means for passing a bundle of light toward a substantial area of the front surface, means for polarizing the light prior to its reaching the front surface, means oriented normally to the polarizing means for analyzing the light emerging from the rear surface after its passage through the medium, means for periodically straining the medium at equally spaced intervals along a direction substantially parallel to the front and rear surfaces in order to alter the refractive index of the medium at the said intervals by a predetermined amount along one direction substantially parallel to the said surfaces and by a diflferent amount along a direction at an angle to the said one direction, thereby to render the medium periodically birefringent, means for varying the periodic birefringence in accordance with a signal, and means positioned beyond the analyzing means for rendering the signal detectable.
  • Apparatus as set forth in claim 14 the medium of which is initially strain-free and the straining means of which comprises means for propagating ultrasound waves into the medium.
  • a communication system having, in com bination, a medium having substantially parallel front and rear surfaces separated by a thickness T. that is transparent to light, and that is of refractive index 11, means for passing a bundle of light having a predetermined wavelength 1 toward a substantial area of the front surface, means for plane-polarizing the light prior to its reaching the front surface, means for analyzing the light emerging from the rear surface after its passage through the medium in the direction of the thickness '1, means for periodically straining the medium at equally spaced intervals along a direction substantially parallel to the front and rear surfaces in order to alter the refractive index of the medium at the said intervals by an amount dni along one direction at an angle to the plane of polarization of the light and by a different amaunt dm along a second direction at right angles to the said one direction, thereby to shift the phase of the component of the polarized light substantially parallel to the said one direction by an amount and -to shift the phase of the component of the polarized light substantially parallel to the said second direction by an amount whereby
  • a communication system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at vibrational wavelengths less than a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through the medium along the predetermined direction a bundle of light of cross-dimension large compared to the dimension of the standing waves, a polarizer for polarizing the light prior to its passage through the medium, an analyzer for extinguishing the light after its passage through the medium, a plurality of means disposed adjacent one of the said edges of the medium for producing molecular vibrations of the said vibrational wavelengths and for directing the vibrations into the medium toward the said other edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves, means connected to the vibrating
  • a communication system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at vibrational wavelengths less than a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through the medium along the predetermined direction a bundle of light of cross-dimension large compared to the dimension of the standing waves, a polarizer for polarizing the light prior to its passage through the medium, an analyzer for extinguishing the light after its passage through the medium, a plurality of piezoelectric crystals disposed adjacent one of the said edges of the medium for producing molecular vibrations of the said vibrational wavelengths and for directing the vibrations into the medium toward the said other edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves, means
  • a transmitter having, in combination, a medium that is transparent to light along a Predetermined direction and that, when molecularly vibrated at vibrational wavelengths less than a predetermined vibrational wavelength to produce standing waves therein between a pair of edges or tne medium spaced from each other in a direction substantially prependicular to the said predetermined direction a distance corresponding to severaltimes the said wavelength, becomes birefringent to light passing therethrough along the predetermined direction, means for passing light through the medium along the predetermined direction, a polarizer for polarizing the light prior to its passage through the medium, a plurality of means disposed adjacent one of the said edges of the medium for producing molecular vibrations of the said vibrational wavelengths and for directing the vibrations into the medium toward the said other edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves, and means connected to the vibrating means for modulating the molecular vibrations of the medium.
  • a transmitting system having, in combination, a. medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined directlon a distance corresponding to several times the said wavelength. becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through a plurality of successive portions of the medium disposed between the said edges.
  • a transmitting system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined ultrasonic vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through a plurality of successive portions of the medium disposed between the said edges, each of width substantially equal to the halfwavelength of the standing waves, along the predetermined direction, a beam of light having a plurality of successive portions corresponding to the plurality of successive half-wavelength portions of the medium, plane-polarizing means disposed to polarize the successive beam portions prior to their passage through the corresponding medium portions, means for producing molecular vibrations of the said predetermined wavelength at one of the said edges of the medium, means for directing the vibrations into the medium toward the other said edge of the medium in order that the
  • a transmitting system having, in combination, a medium that is transparent to light along a predetermined direction and that. when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through a plurality of successive portions of the medium disposed between the said edges, each of width substan tially equal to the half-wavelength of the standing waves, along the predetermined direction, a beam of light having a plurality of successive portions corresponding to the plurality of successive half-wavelength portions of the medium, plane-polarizing means disposed to polarize the successive beam portions prior to their passage through the corresponding medium portions at forty-five degrees with respect to the direction of propagation of the standing waves, means for' producing molecular vibrations oi.
  • a transmitting system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a. direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through a plurality of successive portions of the medium disposed between the said edges. each of width substantially equal to the half-wavelength of the standing waves.
  • a beam of light having a plurality of successive portions corresponding to the plurality of successive half-wavelengh portions of the medium, plane-polarizing means disposed to polarize the successive beam portions prior to their passage through the corresponding medium portions in a plane parallel to the said predetermined direction, means for producing molecular vibrations of the said predetermined wavelength at one of the said edges of the medium, means for directing the vibrations into the medium toward the other said edge of the medium in order that the vibrations may be reflected therefrom to set up the said standing waves, thereby rendering the successive medium portions birefringent in antiphase in response to the resulting standing waves, and means for modifying the vibrations in accordance with a signal.
  • a transmitting system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined vibrational wavelength to produce standing waves therein between a pair or edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes birefringent to the light passing therethrough along the predetermined direction, means for passing through a plurality of successive portions of the medium disposed between the said edges.
  • a communication system having, in combination, a medium that is transparent to light along a predetermined direction and that, when molecularly vibrated at a predetermined ultrasonic carrier vibrational wavelength to produce standing waves therein between a pair of edges of the medium spaced from each other in a direction substantially perpendicular to the said predetermined direction a distance corresponding to several times the said wavelength, becomes bir f n t0 he li h passing therethrough along the predetermined direction, means for determined direction, a beam of light having a plurality of successive portions correspondnig to the plurality oi successive half-wavelength portions of the medium.
  • plane-polarizing means disposed to polarize the successive beam ortions prior to their passage through the corresponding medium portions, means for producing molecular vibrations of the said predetermined wavelength at one of the said edges of the medium, means for directing the vibrations into the medium toward the other said edge oi the medium in order that the vibrations may be reflected therefrom to set up the said standing waves. thereby rendering the successive medium portions birefringent in anti-phase, means for modulating the amplitude of the carrier-wave vibrations in accordance with a signal of greater wavelength, means for receiving the light passed through the medium, means for converting the received light into planepolarized light, and means for detecting the modulation of greater wavelength upon the ultrasonic carrier wavelength as variations in the converted light to reproduce the signal of greater wavelength.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US1002A 1948-01-07 1948-01-07 Modulated light communication system Expired - Lifetime US2623165A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
BE552939D BE552939A (ru) 1948-01-07
US1002A US2623165A (en) 1948-01-07 1948-01-07 Modulated light communication system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1002A US2623165A (en) 1948-01-07 1948-01-07 Modulated light communication system
GB3381956A GB823801A (en) 1956-11-06 1956-11-06 Light modulation system

Publications (1)

Publication Number Publication Date
US2623165A true US2623165A (en) 1952-12-23

Family

ID=33100041

Family Applications (1)

Application Number Title Priority Date Filing Date
US1002A Expired - Lifetime US2623165A (en) 1948-01-07 1948-01-07 Modulated light communication system

Country Status (2)

Country Link
US (1) US2623165A (ru)
BE (1) BE552939A (ru)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707749A (en) * 1949-06-21 1955-05-03 Rines Robert Harvey System of light beam communication
US2807799A (en) * 1951-03-23 1957-09-24 Fairchild Camera Instr Co Light-modulator recording means
US3102203A (en) * 1960-04-15 1963-08-27 Gen Dynamics Corp Photosensitive data providing system
DE1222165B (de) * 1962-10-30 1966-08-04 Ibm Einrichtung zum Modulieren einer elektromagnetischen Strahlung in einer Festkoerpervorrichtung
US3379887A (en) * 1965-12-01 1968-04-23 Gen Dynamics Corp Electro-optical modulator
US3457425A (en) * 1966-02-24 1969-07-22 Perkin Elmer Corp Optical correlator modulating light twice in ultrasonic light modulator
US3536374A (en) * 1966-07-18 1970-10-27 Perkin Elmer Corp Electromechanical variable birefringent light valve
US3600611A (en) * 1970-03-18 1971-08-17 Kettering Scient Research Inc Elasto-optic device with mechanical bias
US3714438A (en) * 1970-07-20 1973-01-30 Univ California Method and apparatus for propagating traveling wave energy through resonant matter
WO2008047245A3 (en) * 2006-10-20 2009-04-23 Crystalith Ltd Optical devices based on internal conical diffraction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707749A (en) * 1949-06-21 1955-05-03 Rines Robert Harvey System of light beam communication
DE1119414B (de) * 1949-06-21 1961-12-14 Mueller Hans Lichtmodulator oder Lichtverschluss
US2807799A (en) * 1951-03-23 1957-09-24 Fairchild Camera Instr Co Light-modulator recording means
US3102203A (en) * 1960-04-15 1963-08-27 Gen Dynamics Corp Photosensitive data providing system
DE1222165B (de) * 1962-10-30 1966-08-04 Ibm Einrichtung zum Modulieren einer elektromagnetischen Strahlung in einer Festkoerpervorrichtung
US3379887A (en) * 1965-12-01 1968-04-23 Gen Dynamics Corp Electro-optical modulator
US3457425A (en) * 1966-02-24 1969-07-22 Perkin Elmer Corp Optical correlator modulating light twice in ultrasonic light modulator
US3536374A (en) * 1966-07-18 1970-10-27 Perkin Elmer Corp Electromechanical variable birefringent light valve
US3600611A (en) * 1970-03-18 1971-08-17 Kettering Scient Research Inc Elasto-optic device with mechanical bias
US3714438A (en) * 1970-07-20 1973-01-30 Univ California Method and apparatus for propagating traveling wave energy through resonant matter
WO2008047245A3 (en) * 2006-10-20 2009-04-23 Crystalith Ltd Optical devices based on internal conical diffraction
US20090168613A1 (en) * 2006-10-20 2009-07-02 Crystalith Ltd. Optical devices based on internal conical diffraction
US8514685B2 (en) 2006-10-20 2013-08-20 Bioaxial Sas Optical devices based on internal conical diffraction

Also Published As

Publication number Publication date
BE552939A (ru)

Similar Documents

Publication Publication Date Title
US2707749A (en) System of light beam communication
US3324295A (en) Frequency modulation discriminator for optical signals
US2622470A (en) Method of and system for indicating the light modulation in a transparent medium
US3302027A (en) Interferometric method and apparatus for modulation and control of light
US3272988A (en) Polarization modulation system for transmitting and receiving two independent signals over a single electromagnetic carrier
US2623165A (en) Modulated light communication system
US2418964A (en) Electromechanical apparatus
US5150228A (en) Real-time edge-enhanced optical correlator
US3539245A (en) Laser-acoustic signal processor
GB1173772A (en) Improvements in or relating to Vibration Responsive Apparatus
US2745316A (en) High efficiency polarizing light valve
US2455763A (en) Interferometric light valve
US2308360A (en) Light modulating apparatus and method
US3365581A (en) Optical modulators
US3419322A (en) Ultrasonic transducer matching for bragg reflection scanning
US2557974A (en) Light modulation system
US3600611A (en) Elasto-optic device with mechanical bias
US3653765A (en) Acousto-optic light spectrum analysis
GB1358671A (en) Method and apparatus for control of light transmission through an anisotropic medium
US3756689A (en) Electronically tunable acousto-optic filter having selected crystal orientation
US3602577A (en) Optical tunneling acoustic surface wave light modulator
US3667038A (en) Acousto-optic rf spectrum analysis method and apparatus
US3379887A (en) Electro-optical modulator
US3437399A (en) Solid-state crystal optical modulator
JP3879805B2 (ja) 光学フィルタリング装置および方法