LASER IMAGING DEVICE

• US 3,818,129 A
• Filed: 06/27/1972
• Issued: 06/18/1974
• Est. Priority Date: 06/30/1971
• Status: Expired due to Term

• Current Assignee: Manabu Yamamoto
• Original Assignee: Manabu Yamamoto
• Inventors: Yamamoto, Manabu
• Primary Examiner(s): Murray, Richard
• Application Number:
  US05/266,636
• Time in Patent Office: 721 Days
• Field of Search: 178/7.3D,6.8,7.5R 250/199
• US Class Current: 348/754
• CPC Class Codes: H01S 3/093 focusing or directing the excitation energy into the active medium
• CPC Class Codes: H01S 3/2383 Parallel arrangements
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

This invention relates to the imaging device in which a spatial picture corresponding to an original picture is reproduced from a time-sequence video-signal corresponding to said original picture. Said device comprises means with which an acoustic wave propagated through an acousto-optic medium such as the transparent saphire crystal is modulated by said time-sequence video-signal, thereby to convert a time-sequence distribution of said signal into a spatial distribution of an optical property of said medium, and means which irradiates pulse laser light beam and which emits said light beam in a manner to be synchronized in time with said video-signals. If the laser light beams of different colors is used in this device, the multi-color imaging device is obtained.

Claims

1. An imaging device in which a spatial picture corresponding to an original picutre is reproduced from a time-sequence videosignal corresponding to said original picture, said device comprising means with which an acoustic wave propagated through an acousto-optic medium is modulated by said time-sequence videosignal, thereby to convert a time-sequence distribution of said video-signal into a spatial distribution of an optical property of said medium, means which irradiates pulse laser light beam having wavelength of ultraviolet range on said medium and which emits said light beam in a manner to be synchronized in time with said video-signal, and means which convert said ultraviolet light emitted from said medium to visible light on the projection screen.

2. An imaging device in which a spacial picture corresponding to an original picture is reproduced from a time-sequence video-signal corresponding to said original picture, said device comprising means with which an acoustic wave propagated through an acousto-optic medium is modulated by said time-sequence video-signal, thereby to convert a time-sequence distribution of said video-signal into a spatial distribution of an optical property of said medium, and means which irradiates pulse laser light beam on said medium and which emits said light beam in a manner to be synchronized with said video-signal, wherein the emitting time of said light beam is not greater than H/N, where H is the line scanning time defined as a duration of the video-signal in which a scanning line of the spatial picture is involved, and N is the number of the picture elements contained in said scanning line.

3. An imaging device according to claim 2, wherein the length of said acousto-optic medium is nearly equal to the distance which the acoustic wave propagates through said medium during said line scanning time.

4. An imaging device according to claim 3, wherein said laser means produces pulses spaced in time from each other equal to the line scanning time, and including means for deflecting the laser light beAm emerging from said acousto-optic medium an amount equal to the distance between successive lines during the scanning time and in the direction as measured transverse to the lines with respect to the spatial picture.

5. An imaging device according to claim 3, including an optical means for diverging the laser beam to the length of the acousto-optic medium and further optic means for converting the diverging laser beam of said length to a parallel laser beam of said length prior to said laser beam reaching said acousto-optic medium.

6. An imaging device according to claim 2, including a high frequency power source for producing an acoustic wave to be modulated, and means which compensates for attenuation of said acoustic wave propagated through said acousto-optic-medium in such a manner that the high-frequency power source exciting said acoustic wave is so made that, when viewed in respect of one scanning line, the power output of said source decreases from the leading end towards the trailing end thereof, so as to return to the original output level again at the leading end of the succeeding scanning line.

7. An imaging device according to claim 6, wherein said frequency conversion means comprises a nonlinear optical crystal selected from the group consisting of lithium iodate, barium sodium niobate, cesium dihydrogen arsenate and cesium dideuterium arsenate.

8. An imaging device according to claim 2, wherein said means to generate said pulse laser light beam comprises a laser device containing neodymium as an active material and frequency conversion means to convert the wavelength of the output of said laser device.

9. An imaging device according to claim 2, wherein, when the wavelength of said pulse laser light beam is lambda , the wavelength of said acoustic wave is Lambda and the incident angle of said light beam to the wave-front of said wave is theta , the relation between said lambda and Lambda is so selected as to satisfy the condition of 2 sin theta lambda / Lambda .

10. An imaging device for reproducing a multicolor spatial picture from multicolor video-signals, comprising means with which n acoustic waves propagated through an acousto-optic medium are modulated by n time-sequence video-signals corresponding to an original picture of n kinds of colors, thereby to convert said n time-sequence video-signals into a spatial distribution of an optical property of said medium, and means which irradiates pulse laser light beams of said n kinds of colors on said medium and which emits said light beams in a manner to be synchronized in time with the respective ones of said n video-signals, wherein the emitting time of the respective ones of said light beams is not greater than H/N, where H is the line scanning time defined as a duration of the video-signal in which a scanning line of the spatial picture is involved, and N is the number of the picture elements contained in said scanning line.

11. An imaging device according to claim 10, wherein the length of said acousto-optic medium is nearly equal to the distance which the acoustic waves propagate through said medium during said line scanning time.

12. An imaging device according to claim 10, including a high frequency power source for producing an acoustic wave to be modulated and means which compensates for attenuation of the respective ones of said acoustic waves propagated through said acousto-optic medium in such a manner that the high-frequency power source exciting said acoustic waves is so made that, when viewed in respect of one scanning line, the power output of said source decreases from the leading end towards the trailing end thereof, so as to return to the original output level again at the leading end of the succeeding scanning line.

13. An imaging device according to claim 10, wherein said means to generate said n pulse laser light beams comprise n laser devices containing neodymium as an active material and frequency conversion Means to convert the wavelength of the output light of said n laser devices.

14. An imaging device according to claim 13, wherein said frequency conversion means comprises a nonlinear optical crystal selected from the group consisting of lithium iodate, barium sodium niobate, cesium dihydrogen arsenate and cesium dideuterium arsenate.

15. An imaging device according to claim 10, wherein, when the wavelength of said n pulse laser light beams are lambda 1, lambda 2, --- lambda n, the wavelength of said n acoustic waves are Lambda 1, Lambda 2, ---n, and the incident angle of said light beams to the wavefront of said waves is A, the relation between said lambda 1, lambda 2, --- lambda n and Lambda 1, Lambda 2, --- Lambda n respectively are so selected as to satisfy the conditions of 2 sin A lambda 1/ Lambda 2 lambda 2/ Lambda 2 --- lambda n/ Lambda n.

16. An imaging device for reproducing a multicolor spatial picture from multicolor video-signals, comprising means in which n acoustic waves propagated through respective n acousto-optic mediums are modulated by the respective ones of n time-sequence video-signals corresponding to a multicolored original picture synthesized by n kinds of colors, thereby to convert said n time-sequence video-signals into a spatial distribution of an optical property of the respective ones of said n mediums, each which irradiates pulse laser light beams of said n kinds of colors on said mediums and which emits said light beams in a manner to be synchronized in time with the respective ones of said n video-signals, wherein the emitting time of the respective ones of said light beams is not greater than H/N, wherein H is a line scanning time and N is the number of the picture elements contained in a scanning line of the spatial picture corresponding to the video-signal of said scanning time.