Abstract

Bragg reflection of laser light by ultrasonic waves in water produces the horizontal deflection in a television display. The ultrasonic waves are frequency-modulated with a sawtooth function. Deflection angles are small but there are 200 resolvable positions; the constant rate of angular change which characterizes a television scan permits the use of a wide optical aperture, leading to a small spot size. Conventional optical magnification follows the horizontal deflection, rendering a 3 MHz video signal visible on the screen.

Bragg reflection requires the acoustic wave front to be symmetrical with respect to the incident and diffracted light rays. Thus, as the Bragg angle is altered, the acoustic wavefront should rotate. This is accomplished by a phased array of transducer strips whose combined wavefront rotates as the frequency changes, providing excellent correction over a wide band (19 to 35 MHz in this experiment, corresponding to a ±30 percent change in Bragg angle). Broadband electrical and acoustical matching techniques make it possible to diffract all the incident light with about one watt of electrical input.

A second acoustic diffraction cell intensity-modulates the light. In an early experiment, the laser beam was constricted to a very small diameter before entering the modulator cell; even so, the finite beam size caused a significant loss of high-frequency response. An improved version uses an old principle (Scophony, 1939): the laser beam traversing the cell is made wide enough to encompass several picture elements, all traveling across the beam at sound velocity; the horizontal deflection system nullifies the apparent motion of these elements making them stand still on the screen while a fan of light sweeps over them. With this modulation system, spatial coherence is needed only across the vertical dimension of the laser.

The tolerance on the orientation of the acoustic wavefronts, the improvement brought about by the phased array, and the amount of power needed to drive the diffraction cell are calculated and the results confirmed by measurement. There is also good agreement between the experimentally observed optical resolution (spatial frequency response) and the theoretical expectation based on the computed far-field intensity pattern.

© 1966 Optical Society of America

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References

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  1. C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
    [CrossRef]
  2. A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
    [CrossRef]
  3. J. S. Gerig, H. Montague, “A simple optical filter for chirp radar,” Proc. IEEE (Correspondence), vol. 52, p. 1753, December1964.
    [CrossRef]
  4. For a general discussion, see Born, Wolf, Principles of Optics. New York: Pergamon, 1959, ch. 12. Other references in bibliography of [1].
  5. M. G. Cohen, E. I. Gordon, “Acoustic beam probing using optical techniques,” Bell Sys. Tech. J., vol. XLIV, pp. 693–721, April1965.
  6. A. Korpel, R. Adler, P. Desmares, “An improved ultrasonic light deflection system,” presented at the Electron Devices Meeting, Washington, D. C., October 1965.
  7. D. A. Berlincourt, D. R. Curran, H. Jaffe, Physical Acoustics, vol. I, part A., W. P. Mason, Ed. New York and London: Academic, 1964, ch. 3, pp. 245–246.
  8. H. V. Hance, J. K. Parks, “Wide-band modulation of a laser beam, using Bragg-angle diffraction by amplitude-modulated ultrasonic waves,” J. Acoust. Soc. Am., vol. 38, pp. 14–23, July1965. This also contains earlier references. See particularly I. I. Adrianova, “Frequency characteristics of diffraction modulators of light with ferroelectric-ceramic emitters of ultrasound,” Opt. and Spectr., vol. xii, pp. 48–51, January1962.
    [CrossRef]
  9. F. Okolicsanyi, “The wave-slot, an optical television system,” The Wireless Engr., vol. 14, pp. 527–536, October1937. Also, D. M. Robinson, “The supersonic light control and its application to television with special reference to the Scophony television receiver,” Proc. IRE, vol. 27, pp. 483–486, August1939.
    [CrossRef]
  10. T. M. Smith, A. Korpel, “Measurement of light-sound interaction efficiencies in solids,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 283–284, September1965.
    [CrossRef]

1965 (5)

C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
[CrossRef]

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

M. G. Cohen, E. I. Gordon, “Acoustic beam probing using optical techniques,” Bell Sys. Tech. J., vol. XLIV, pp. 693–721, April1965.

H. V. Hance, J. K. Parks, “Wide-band modulation of a laser beam, using Bragg-angle diffraction by amplitude-modulated ultrasonic waves,” J. Acoust. Soc. Am., vol. 38, pp. 14–23, July1965. This also contains earlier references. See particularly I. I. Adrianova, “Frequency characteristics of diffraction modulators of light with ferroelectric-ceramic emitters of ultrasound,” Opt. and Spectr., vol. xii, pp. 48–51, January1962.
[CrossRef]

T. M. Smith, A. Korpel, “Measurement of light-sound interaction efficiencies in solids,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 283–284, September1965.
[CrossRef]

1964 (1)

J. S. Gerig, H. Montague, “A simple optical filter for chirp radar,” Proc. IEEE (Correspondence), vol. 52, p. 1753, December1964.
[CrossRef]

1937 (1)

F. Okolicsanyi, “The wave-slot, an optical television system,” The Wireless Engr., vol. 14, pp. 527–536, October1937. Also, D. M. Robinson, “The supersonic light control and its application to television with special reference to the Scophony television receiver,” Proc. IRE, vol. 27, pp. 483–486, August1939.
[CrossRef]

Adler, R.

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

A. Korpel, R. Adler, P. Desmares, “An improved ultrasonic light deflection system,” presented at the Electron Devices Meeting, Washington, D. C., October 1965.

Berlincourt, D. A.

D. A. Berlincourt, D. R. Curran, H. Jaffe, Physical Acoustics, vol. I, part A., W. P. Mason, Ed. New York and London: Academic, 1964, ch. 3, pp. 245–246.

Born,

For a general discussion, see Born, Wolf, Principles of Optics. New York: Pergamon, 1959, ch. 12. Other references in bibliography of [1].

Cohen, M. G.

M. G. Cohen, E. I. Gordon, “Acoustic beam probing using optical techniques,” Bell Sys. Tech. J., vol. XLIV, pp. 693–721, April1965.

Curran, D. R.

D. A. Berlincourt, D. R. Curran, H. Jaffe, Physical Acoustics, vol. I, part A., W. P. Mason, Ed. New York and London: Academic, 1964, ch. 3, pp. 245–246.

Desmares, P.

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

A. Korpel, R. Adler, P. Desmares, “An improved ultrasonic light deflection system,” presented at the Electron Devices Meeting, Washington, D. C., October 1965.

Gerig, J. S.

J. S. Gerig, H. Montague, “A simple optical filter for chirp radar,” Proc. IEEE (Correspondence), vol. 52, p. 1753, December1964.
[CrossRef]

Gordon, E. I.

M. G. Cohen, E. I. Gordon, “Acoustic beam probing using optical techniques,” Bell Sys. Tech. J., vol. XLIV, pp. 693–721, April1965.

Hance, H. V.

H. V. Hance, J. K. Parks, “Wide-band modulation of a laser beam, using Bragg-angle diffraction by amplitude-modulated ultrasonic waves,” J. Acoust. Soc. Am., vol. 38, pp. 14–23, July1965. This also contains earlier references. See particularly I. I. Adrianova, “Frequency characteristics of diffraction modulators of light with ferroelectric-ceramic emitters of ultrasound,” Opt. and Spectr., vol. xii, pp. 48–51, January1962.
[CrossRef]

Jaffe, H.

D. A. Berlincourt, D. R. Curran, H. Jaffe, Physical Acoustics, vol. I, part A., W. P. Mason, Ed. New York and London: Academic, 1964, ch. 3, pp. 245–246.

Korpel, A.

T. M. Smith, A. Korpel, “Measurement of light-sound interaction efficiencies in solids,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 283–284, September1965.
[CrossRef]

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

A. Korpel, R. Adler, P. Desmares, “An improved ultrasonic light deflection system,” presented at the Electron Devices Meeting, Washington, D. C., October 1965.

Montague, H.

J. S. Gerig, H. Montague, “A simple optical filter for chirp radar,” Proc. IEEE (Correspondence), vol. 52, p. 1753, December1964.
[CrossRef]

Okolicsanyi, F.

F. Okolicsanyi, “The wave-slot, an optical television system,” The Wireless Engr., vol. 14, pp. 527–536, October1937. Also, D. M. Robinson, “The supersonic light control and its application to television with special reference to the Scophony television receiver,” Proc. IRE, vol. 27, pp. 483–486, August1939.
[CrossRef]

Parks, J. K.

H. V. Hance, J. K. Parks, “Wide-band modulation of a laser beam, using Bragg-angle diffraction by amplitude-modulated ultrasonic waves,” J. Acoust. Soc. Am., vol. 38, pp. 14–23, July1965. This also contains earlier references. See particularly I. I. Adrianova, “Frequency characteristics of diffraction modulators of light with ferroelectric-ceramic emitters of ultrasound,” Opt. and Spectr., vol. xii, pp. 48–51, January1962.
[CrossRef]

Quate, C. F.

C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
[CrossRef]

Smith, T. M.

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

T. M. Smith, A. Korpel, “Measurement of light-sound interaction efficiencies in solids,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 283–284, September1965.
[CrossRef]

Wilkinson, C. D. W.

C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
[CrossRef]

Winslow, D. K.

C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
[CrossRef]

Wolf,

For a general discussion, see Born, Wolf, Principles of Optics. New York: Pergamon, 1959, ch. 12. Other references in bibliography of [1].

Bell Sys. Tech. J. (1)

M. G. Cohen, E. I. Gordon, “Acoustic beam probing using optical techniques,” Bell Sys. Tech. J., vol. XLIV, pp. 693–721, April1965.

IEEE J. of Quantum Electronics (Correspondence) (2)

A. Korpel, R. Adler, P. Desmares, T. M. Smith, “An ultrasonic light deflection system,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 60–61, April1965.
[CrossRef]

T. M. Smith, A. Korpel, “Measurement of light-sound interaction efficiencies in solids,” IEEE J. of Quantum Electronics (Correspondence), vol. QE-1, pp. 283–284, September1965.
[CrossRef]

J. Acoust. Soc. Am. (1)

H. V. Hance, J. K. Parks, “Wide-band modulation of a laser beam, using Bragg-angle diffraction by amplitude-modulated ultrasonic waves,” J. Acoust. Soc. Am., vol. 38, pp. 14–23, July1965. This also contains earlier references. See particularly I. I. Adrianova, “Frequency characteristics of diffraction modulators of light with ferroelectric-ceramic emitters of ultrasound,” Opt. and Spectr., vol. xii, pp. 48–51, January1962.
[CrossRef]

Proc. IEEE (1)

C. F. Quate, C. D. W. Wilkinson, D. K. Winslow, “Interaction of light and microwave sound,” Proc. IEEE, vol. 53, pp. 1604–1623, October1965.
[CrossRef]

Proc. IEEE (Correspondence) (1)

J. S. Gerig, H. Montague, “A simple optical filter for chirp radar,” Proc. IEEE (Correspondence), vol. 52, p. 1753, December1964.
[CrossRef]

The Wireless Engr. (1)

F. Okolicsanyi, “The wave-slot, an optical television system,” The Wireless Engr., vol. 14, pp. 527–536, October1937. Also, D. M. Robinson, “The supersonic light control and its application to television with special reference to the Scophony television receiver,” Proc. IRE, vol. 27, pp. 483–486, August1939.
[CrossRef]

Other (3)

For a general discussion, see Born, Wolf, Principles of Optics. New York: Pergamon, 1959, ch. 12. Other references in bibliography of [1].

A. Korpel, R. Adler, P. Desmares, “An improved ultrasonic light deflection system,” presented at the Electron Devices Meeting, Washington, D. C., October 1965.

D. A. Berlincourt, D. R. Curran, H. Jaffe, Physical Acoustics, vol. I, part A., W. P. Mason, Ed. New York and London: Academic, 1964, ch. 3, pp. 245–246.

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Figures (11)

Fig. 1
Fig. 1

Characteristic angles and optical resolution of a Bragg diffraction cell.

Fig. 2
Fig. 2

Efficiency of light diffraction process vs. optical phase excursion, Δϕ in the acoustic medium. Δϕ is proportional to sound pressure.

Fig. 3
Fig. 3

Diffraction of light in the phased-array scanner. As frequency changes, acoustic wavefronts W rotate to track changing Bragg angle. Condition shown corresponds to Λ<Λ0.

Fig. 4
Fig. 4

Plot of diffracted light intensity vs. cell orientation with (a) rotating acoustic wavefronts tracking Bragg angle and (b) stationary acoustic wavefronts. 19 and 35 MHz curves are lower than 27 MHz curve because of transducer frequency response; see also Fig. 6.

Fig. 5
Fig. 5

Perspective view of the stair-step transducer mounting with broadband electrical matching elements, showing the emerging sound beam.

Fig. 6
Fig. 6

Diffracted light intensity vs. frequency at low power input.

Fig. 7
Fig. 7

Two aspects of optical resolution. (a) Far-field intensity pattern (b) Spatial frequency response.

Fig. 8
Fig. 8

Light intensity vs. time, recorded with the diffracted light scanning across a narrow slit. The time scale is 0.5 μs/major div.

Fig. 9
Fig. 9

Scophony image immobilization system applied to acoustic deflection. Image detail traveling through modulation cell is rendered stationary on the screen by continuous change of deflection angle. At any instant, several picture elements are present on the screen.

Fig. 10
Fig. 10

Essential components of the laser TV display system. Direction of sound wave in modulator is reversed from Fig. 9 to allow introduction of a telescope between modulator and deflector.

Fig. 11
Fig. 11

Test pattern photographed by putting 4×5 inch Polaroid film in place of screen. This procedure, possible only in a projection system, produces a reversed image.

Equations (12)

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α d = λ V Δ f .
N = α T / α min = D V Δ f = τ Δ f
α d ( t , y ) = α T T ( t - y / V ) .
d / d y ( α d ) = - α T / V T
P ( ψ ) / P ( O ) = [ sin ( π l ψ / Λ ) / ( π l ψ / Λ ) ] 2
d / d Λ ( 1 2 λ / Λ + 1 2 Λ / s ) = 0.
Δ n = ( n 2 - 1 ) ( n 2 + 2 ) 6 n .
P π = 9 2 ρ V 3 λ 2 ( n 3 + n - 2 / n ) 2 h / l .
I 1 ( β ) / I 1 ( 0 ) = [ sin ( π β D / λ ) / π β D / λ ) ] 2
A A = - + I 1 ( β ) cos m β d β - + I 1 ( β ) d β .
f max · T = α T D / λ = N .
L = V T / α T .

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