GB2221053A - Spatial light modulators - Google Patents
Spatial light modulators Download PDFInfo
- Publication number
- GB2221053A GB2221053A GB8912781A GB8912781A GB2221053A GB 2221053 A GB2221053 A GB 2221053A GB 8912781 A GB8912781 A GB 8912781A GB 8912781 A GB8912781 A GB 8912781A GB 2221053 A GB2221053 A GB 2221053A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light modulator
- spatial light
- modulator
- mirror
- gallium arsenide
- 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.)
- Granted
Links
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims abstract description 14
- 239000004065 semiconductor Substances 0.000 claims abstract description 11
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 claims description 9
- MDPILPRLPQYEEN-UHFFFAOYSA-N aluminium arsenide Chemical compound [As]#[Al] MDPILPRLPQYEEN-UHFFFAOYSA-N 0.000 abstract description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 abstract 1
- 229910052733 gallium Inorganic materials 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052594 sapphire Inorganic materials 0.000 description 4
- 239000010980 sapphire Substances 0.000 description 4
- 238000005530 etching Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 2
- 230000001427 coherent effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000001429 visible spectrum Methods 0.000 description 2
- 229910005540 GaP Inorganic materials 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- HZXMRANICFIONG-UHFFFAOYSA-N gallium phosphide Chemical compound [Ga]#P HZXMRANICFIONG-UHFFFAOYSA-N 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
-
- 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
- G02F1/015—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 semiconductor elements having potential barriers, e.g. having a PN or PIN junction
-
- 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
- G02F1/015—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 semiconductor elements having potential barriers, e.g. having a PN or PIN junction
- G02F1/017—Structures with periodic or quasi periodic potential variation, e.g. superlattices, quantum wells
- G02F1/01716—Optically controlled superlattice or quantum well devices
-
- 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
- G02F1/015—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 semiconductor elements having potential barriers, e.g. having a PN or PIN junction
- G02F1/0155—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 semiconductor elements having potential barriers, e.g. having a PN or PIN junction modulating the optical absorption
- G02F1/0157—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 semiconductor elements having potential barriers, e.g. having a PN or PIN junction modulating the optical absorption using electro-absorption effects, e.g. Franz-Keldysh [FK] effect or quantum confined stark effect [QCSE]
-
- 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
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/34—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 reflector
- G02F2201/346—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 reflector distributed (Bragg) reflector
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biophysics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Light Receiving Elements (AREA)
Abstract
An optically addressable spatial light modulator comprises an electrically conducting dielectric mirror 3 with a phototransistor array 1 at one face and a semiconductor light modulator 2 at the other face. The light modulator may be a quantum well structure or a bulk semiconductor Franz-Keldysh modulator. The spatial light modulator is preferably formed of layers of gallium arsenide and gallium aluminium arsenide. <IMAGE>
Description
Spatial light modulators.
The present invention relates to spatial light modulators, and in particular to optically-addressable spatial light modulators.
Present spatial light modulators either use liquid crystal "light valves" to modulate a pump beam from a laser, or comprise an array of optical transistors in series with a transmission modulator.
The latter form, however, suffers from the inconvenience of focussing a weak input beam and an intense pump beam onto a large number of interleaved diffraction limited spots on the same side of the device, since any stray photons from the pump beam finding their way into an input path or directly onto the base of an optical transistor will appear as input noise which will then be amplified.
According to one aspect of the present invention an optically addressable spatial light modulator comprises an electrically conducting dielectric mirror, at least one phototransistor disposed adjacent one face of said mirror and a semiconductor light modulator disposed adjacent the other face of said mirror.
The spatial light modulator may be fabricated as a layered structure of gallium arsenide and aluminium gallium arsenide.
According to another aspect of the present invention an optically addressable spatial light modulator comprises an electrically conducting dielectric mirror, an array of photo transistors disposed adjacent one face of said mirror and a semiconductor light modulator arrangement disposed adjacent the other face of said mirror.
The semiconductor modulator arrangement may comprise an array of multiple quantum well modulators or a bulk semiconductor
Franz-Keldysh modulator.
A spatial light modulator in accordance with the present invention will now be described with reference to the accompanying drawing, of which;
Figure 1 shows an element of the modulator schematically, and
Figure 2 shows diagrammatically part of the modulator in cross-section.
Referring first to Figure 1 the spatial light modulator comprises essentially an n-p-n photo transistor or optical transistor 1 connected in series with a PIN diode optical modulator 2, the electrical connection between the transistor 1 and the diode modulator 2 being made by way of an electrically conductive "dielectric mirror" stack 3. Optical input signals, which may be of low intensity and of incoherent broadband light are arranged to be focussed effectively on the base region of the transistor 1, while relatively high intensity coherent radiation at a wavelength of, say, 850nm may be directed at the diode modulator 2 and reflected by the dielectric mirror 3.
As shown in Figure 2 the spatial light modulator structure may be fabricated in gallium arsenide and aluminium gallium arsenide on a gallium arsenide substrate (not shown), the structure being built up as a succession of differently doped layers starting with an n-doped high aluminium content etch-stop layer 4. The diode modulator 2 comprises an n-doped layer 5 of aluminium gallium arsenide, a succession of thin undoped or intrinsic layers 6 alternately of gallium arsenide and aluminium gallium arsenide, which form multiple quantum wells, and a p-doped layer 7 of aluminium gallium arsenide, over which is deposited the conducting 1dielectric mirror" stack 3 of alternate layers of aluminium arsenide and aluminium gallium arsenide all highly p-doped.
The layers making up the photo transistor 1 may be separated from the mirror stack 3 by a highly p-doped absorber layer (not shown) which is intended to absorb any of the coherent radiation at the pumps wavelength of 850nm which may penetrate the mirror stack 3.
The transistor itself may comprise an n-doped collector layer 8 of gallium arsenide, a p-doped base layer 9 of gallium arsenide, and an n-doped emitter layer 10 of aluminium gallium arsenide which is separated from the base layer 9 by a thin region 11 which is linearly graded from undoped gallium arsenide adjacent the base layer 9 to n-doped aluminium gallium arsenide adjacent the emitter layer 10. A final heavily n-doped capping layer 12 of gallium arsenide is provided onto which metallic contacts 13 may be bonded.
The layered structure can be divided into pixels, either by etching to leave mesas or by proton implantation, in a regular grid pattern. If etching is used the gaps between the mesas are infilled with polyimide or photo resist. The metal layer providing the contacts 13 may then be deposited over the whole surface of the structure, and windows may be etched in register with the pixels to allow access of input optical signals to the phototransistor 1.
A sapphire wafer or "substrate" 14 is then glued to the metal contact layer 13, for example using a clear, high thermal conductivity epoxy adhesive, with an index matching material in the window areas to avoid unnecessary reflections of input signals at the air interfaces.
The original gallium arsenide substrate is etched away almost up to the etch stop layer 4, since it is opaque to the optical pump energy at 850nm. A thin layer is, however, retained to aid contacting, and a metal layer is deposited and windows etched in register with those adjacent the sapphire wafer to allow passage of the pump energy and of the output image energy.
Sapphire has the advantage that it provides an excellent heat sink as well as being transparent. Heat is generated in two places in particular in the structure, in the photo transistor 1 due to the amplificaton of the photoelectrons and in the multiple quantum well layers 6 when absorbing the pump energy. The performance of the layers 6 is sensitive to temperature changes, which alter the thickness of the layers and the well widths. In addition the passband of the dielectric mirror 3 will tend to change with temperature.
If required a second sapphire wafer (not shown) may be glued to the modulator side of the structure to form a sandwich which dissipates heat effectively and increases the thermal inertia of the structure, giving greater stability.
Mesa etching may be used to separate the input phototransistor 1 into two or more all with their collectors connected together to the same modulator 2. This results In a multiple input gate arrangement which can be used in a direct optical copy of an electronic digital circuit.
Instead of a gallium arsenide device operating a wavelength of 850nm the structure could be made in indium phosphide to operate at pump wavelengths of 1500nm or in gallium phosphide or indium phosphide to operate in the visible spectrum.
By cascading two spatial light modulators the negative image normally obtained can be reversed and the output image made positive.
Further cascading with progressively stronger pump beams can provide image intensification. For a given input image intensity the pump beam can only be a fixed factor stronger, so cascading allows high intensity images to be obtained.
It is important that as little as possible of the pump energy should find its way through the dielectric mirror 3 into the base of the phototransistor 1. It is known that dielectric mirrors have, for a reasonable number of layers, a reflection efficiency of, say, 95X, but the remainder which does penetrate can be absorbed by the highly doped gallium arsenide absorber (not shown) on the phototransistor side of the dielectric mirror 3.
A second dielectric mirror (not shown) may be incorporated just below the base region 9 of the phototransistor 1 so that any input signal not absorbed on the first pass through the base region 9 is reflection and absorbed during the return pass. This would serve to increase the input efficiency.
The region 6 may be replaced by bulk gallium arsenide so that the modulation can be induced by the Franz-Keldysh effect.
A supply voltage of, say, 5 volts may be maintained in operation between the metal layers on the outer faces of the layered structure.
The spatial light modulator described above has a wide input bandwidth extending from 850nm into the visible spectrum, although the output spectrum is narrow due to the narrow effective bandwidth of the dielectric mirror 3 and the small shift of band edge in the multiple quantum well modulator 2.
Claims (6)
1. An optically addressable spatial light modulator comprising an electrically conducting dielectric mirror, at least one phototransistor disposed adjacent one face of said mirror and a semiconductor light modulator disposed adjacent the other face of said mirror.
2. An optically addressable spatial light modulator in accordance with Claim 1 comprIsing a layered structure of gallium arsenide and aluminium gallium arsenide.
3. An optically addressable spatial light modulator comprising an electrically conducting dielectric mirror, an array of photo transistors disposed adjacent one face of said mirror and a semiconductor light modulator arrangement disposed adjacent the other face of said mirror.
4. An optically addressable spatial light modulator in accordance with Claim 3 wherein the semiconductor modulator arrangement comprises an array of multiple quantum well modulators.
5. An optically addressable spatial light modulator in accordance with Claim 3 wherein the semiconductor modulator arrangement is a bulk semiconductor Franz-Keldysh modulator.
6. An optically addressable spatial light modulator substantially as hereinbefore described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888813483A GB8813483D0 (en) | 1988-06-08 | 1988-06-08 | Spatial light modulators |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8912781D0 GB8912781D0 (en) | 1989-07-19 |
| GB2221053A true GB2221053A (en) | 1990-01-24 |
| GB2221053B GB2221053B (en) | 1992-02-26 |
Family
ID=10638241
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888813483A Pending GB8813483D0 (en) | 1988-06-08 | 1988-06-08 | Spatial light modulators |
| GB8912781A Expired - Fee Related GB2221053B (en) | 1988-06-08 | 1989-06-02 | Spatial light modulators |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888813483A Pending GB8813483D0 (en) | 1988-06-08 | 1988-06-08 | Spatial light modulators |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8813483D0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4103071A1 (en) * | 1990-02-01 | 1991-08-08 | Mitsubishi Electric Corp | LIGHT CONTROLLED SEMICONDUCTOR LIGHT COUPLER AND MODULATOR |
| EP0443332A1 (en) * | 1990-01-23 | 1991-08-28 | Nippon Telegraph And Telephone Corporation | Optical gate array |
| WO1992000543A1 (en) * | 1990-06-29 | 1992-01-09 | The General Electric Company, Plc | Bipolar junction transistor combined with an optical modulator |
| WO2003036367A2 (en) * | 2001-10-22 | 2003-05-01 | Massachusetts Institute Of Technology | Light modulation using the franz-keldysh effect |
| GB2383886A (en) * | 2001-12-20 | 2003-07-09 | Corning Inc | Reflective spatial light modulator comprising dielectric layer/mirror |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1986005598A1 (en) * | 1985-03-18 | 1986-09-25 | American Telephone & Telegraph Company | Nonlinear and bistable optical device |
| WO1987002478A1 (en) * | 1985-10-08 | 1987-04-23 | American Telephone & Telegraph Company | Nonlinear and bistable optical device |
-
1988
- 1988-06-08 GB GB888813483A patent/GB8813483D0/en active Pending
-
1989
- 1989-06-02 GB GB8912781A patent/GB2221053B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1986005598A1 (en) * | 1985-03-18 | 1986-09-25 | American Telephone & Telegraph Company | Nonlinear and bistable optical device |
| WO1987002478A1 (en) * | 1985-10-08 | 1987-04-23 | American Telephone & Telegraph Company | Nonlinear and bistable optical device |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0443332A1 (en) * | 1990-01-23 | 1991-08-28 | Nippon Telegraph And Telephone Corporation | Optical gate array |
| DE4103071A1 (en) * | 1990-02-01 | 1991-08-08 | Mitsubishi Electric Corp | LIGHT CONTROLLED SEMICONDUCTOR LIGHT COUPLER AND MODULATOR |
| WO1992000543A1 (en) * | 1990-06-29 | 1992-01-09 | The General Electric Company, Plc | Bipolar junction transistor combined with an optical modulator |
| US5249074A (en) * | 1990-06-29 | 1993-09-28 | Gec-Marconi Limited | Bipolar junction transistor combined with an optical modulator |
| GB2245758B (en) * | 1990-06-29 | 1994-10-26 | Gen Electric Co Plc | A combined bipolar junction transistor and an optical modulator |
| WO2003036367A2 (en) * | 2001-10-22 | 2003-05-01 | Massachusetts Institute Of Technology | Light modulation using the franz-keldysh effect |
| WO2003036367A3 (en) * | 2001-10-22 | 2003-09-12 | Massachusetts Inst Technology | Light modulation using the franz-keldysh effect |
| US7239762B2 (en) | 2001-10-22 | 2007-07-03 | Massachusetts Institute Of Technology | Light modulation using the Franz-Keldysh effect |
| GB2383886A (en) * | 2001-12-20 | 2003-07-09 | Corning Inc | Reflective spatial light modulator comprising dielectric layer/mirror |
| GB2383886B (en) * | 2001-12-20 | 2005-07-20 | Corning Inc | Spatial light modulators with improved inter-pixel performance |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8912781D0 (en) | 1989-07-19 |
| GB2221053B (en) | 1992-02-26 |
| GB8813483D0 (en) | 1988-07-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4857973A (en) | Silicon waveguide with monolithically integrated Schottky barrier photodetector | |
| US5455421A (en) | Infrared detector using a resonant optical cavity for enhanced absorption | |
| US7196349B2 (en) | Resonant cavity enhanced multi-quantum well light modulator and detector | |
| US4293826A (en) | Hybrid semiconductor laser/detectors | |
| US5051790A (en) | Optoelectronic interconnections for integrated circuits | |
| JP2770996B2 (en) | Multi-channel cavity laser | |
| US5157537A (en) | Distributed resonant cavity light beam modulator | |
| US4297653A (en) | Hybrid semiconductor laser/detectors | |
| KR101974576B1 (en) | Transmitting type optical image modulator having large aperture area and method of manufacturing the same and optical apparatus comprising transmitting type optical image modulator | |
| US4842376A (en) | Double-schottky diode liquid crystal light valve | |
| US5101293A (en) | Electrooptic device for modulation of intensity and phase of transmitted or reflected light at discrete operating wavelengths | |
| US6181398B1 (en) | Multiple pixel driven mirror electrodes for improved aperture ratio of reflective displays | |
| US4784476A (en) | Nipi refractive index modulation apparatus and method | |
| US5742045A (en) | Apparatus using diode laser logic to form a configurable optical gate system | |
| GB2221053A (en) | Spatial light modulators | |
| US3631360A (en) | Electro-optical structures utilizing fresnel optical systems | |
| JPS63502315A (en) | Interconnection of wafer-sized integrated assemblies | |
| JPH0482277A (en) | Semiconductor photodetector | |
| CN111628039A (en) | Silicon substrate nitride multi-quantum well homologism integrated electro-optical modulator and preparation method | |
| US4978208A (en) | Photoelectronic diode spatial light modulator and eye protection goggles incorporating the same | |
| JP2827514B2 (en) | Photoelectric conversion device | |
| KR100213179B1 (en) | Liquid crystal display device light valve | |
| JP2933779B2 (en) | Transmission system | |
| JPH04328726A (en) | Optical neural network device | |
| US3649836A (en) | Electro-optical multiple image arrangements |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940602 |