Display system employing acoustro-optic tunable filter

• US 5,410,371 A
• Filed: 06/07/1993
• Issued: 04/25/1995
• Est. Priority Date: 06/07/1993
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Lambert, James L.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): LEE, MICHAEL
• Application Number:
  US08/073,235
• Time in Patent Office: 687 Days
• Field of Search: 358/55, 358/56, 358/57, 358/60, 358/61, 358/62, 358/63, 358/201, 358/202, 358/199, 358/235, 358/230, 358/231
• US Class Current: 348/769
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 2225/21 Acousto-optic SLM [AO-SLM]
• CPC Class Codes: H04N 3/10 by means not exclusively optical-mechanical H04N3/36 takes precedence
• 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

An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with an RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

Claims

1. A display system apparatus for generating a visual display from an electrical driver signal comprising:

a signal source providing a frequency multiplexed tricolor electrical driver signal comprising a sum of three separate video signals modulated on three respective radio frequency carrier signals;

a light source providing a linearly polarized, pulsed input light beam including red, green, and blue wavelengths;

an acousto-optic tunable filter arranged to receive and be driven by said frequency multiplexed tricolor driver signal;

a scanning mirror positioned to receive said light beam and scan it across said acousto-optic tunable filter; and

wherein said filter produces an output beam in response to said driver signal and said light beam, and further including a beam splitter means for receiving said output beam, for separating it into an undiffracted zero order beam and a first order component, and for selecting the undiffracted zero order beam as the display to be viewed.

2. The display apparatus of claim 1 wherein said driver signal further comprises modulated red, green, and blue video signals.

3. The display apparatus of claim 2 wherein said light beam comprises a collimated laser beam.

4. The display apparatus of claim 3 wherein said collimated laser beam is generated by a helium cadmium laser.

5. The display apparatus of claim 1 wherein said zero order beam is focused directly on the retina of a viewer.

6. A method of providing a color display, comprising the steps of:

scanning a linearly polarized light beam across an acousto-optic tunable filter;

driving said tunable filter with an electrical driver signal comprising frequency modulated red, green, and blue video signals that are modulated on three respective carrier signals, wherein a frequency of each of the red, green, and blue carrier signals is selected to correspond to red, green, and blue spectral lines of the linearly polarized light beam;

splitting the output of said tunable filter into first and zero order components; and

selecting said zero order component to provide said display, wherein a cell aperture of said tunable filter is successively filled with a succession of encoded vertical video scan lines by said driver signal and said light beam is pulsed to periodically illuminate the filled filter.

7. The method of claim 6, further including the step of focusing said zero order component directly to the retina of the eye of a viewer.

8. A display system apparatus for generating a visual display from an electrical signal comprising:

a signal source means for providing a multiplexed tricolor electrical driver signal having three separate frequency components therein at any given time and representing an output scene to be displayed;

a light source means for providing a linearly polarized, pulsed input light beam;

an acousto-optic tunable filter means for receiving and being driven by said multiplexed tricolor driver signal; and

means positioned to receive said light beam from said light source for scanning said light beam across said acousto-optic tunable filter means so as to generate an output beam from said filter means having a representation of said output scene present in an undiffracted zero order output portion thereof; and

means for selecting said undiffracted zero order output portion to provide said display,

wherein said light source comprises a laser means providing red, green, and blue wavelengths, and wherein said signal source means and means for scanning cause said filter means to implement three spectral band-pass filters centered at said red, green, and blue wavelengths, respectively,

wherein said means for selecting comprises beam splitter means for receiving said output beam, separating it into a zero order beam and a first order component, and providing the undiffracted zero order beam to the eye of a viewer.

9. The apparatus of claim 8 wherein said beam splitter means further overlays a real world scene on said display.

10. The apparatus of claim 9 wherein said real world scene is a real-time real world scene.

13. The display system of claim 10 wherein said filter means implements three spectral band-pass filters centered at said red, green, and blue wavelengths.

11. A display system apparatus for generating a visual display comprising:

laser means providing a linearly polarized, pulsed input light beam including red, green, and blue wavelengths;

a signal source means for providing a multiplexed tricolor electrical driver signal representing an output scene to be displayed, said driver signal including three simultaneously added carrier signals with respective wavelengths equal to said red, green, and blue wavelengths, respectively;

an acousto-optic tunable filter means for receiving and being driven by said multiplexed tricolor driver signal, said multiplexed tricolor driver signal successively filling an aperture of the filter means with an encoded vertical scan line; and

means positioned to receive said light beam from said light source for scanning said light beam across said acousto-optic tunable filter means to illuminate said filter during a presence of each successive scan line, so as to generate an output beam from said filter means having a representation of said output scene present in an undiffracted zero order output portion thereof.

12. The display system of claim 11 further including:

means for selecting said undiffracted zero order output portion for use as said visual display.

14. A method of providing a color display, comprising the steps of:

driving an acousto-optic tunable filter with an electrical driver signal comprising frequency modulated red, green, and blue video signals that are modulated on three respective carrier signals, wherein a frequency of each of the red, green, and blue carrier signals is selected to correspond to red, green, and blue spectral lines of the linearly polarized light beam;

successively filling a cell aperture of said filter with an encoded vertical scan line of the electrical driver signal;

scanning a pulse of linearly polarized, collimated light across said filter to illuminate said filter during the presence of each successive scan line;

splitting the output of said tunable filter into first and zero order components; and

selecting said zero order component to provide said display.