Spectral distribution emulation

• US 5,608,213 A
• Filed: 11/03/1995
• Issued: 03/04/1997
• Est. Priority Date: 11/03/1995
• Status: Expired due to Fees

• Current Assignee: United States Air Force (Government of the United States of America)
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Pinkus, Alan R., Task, Harry L.
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US08/552,402
• Time in Patent Office: 487 Days
• Field of Search: 250/494.1, 250/495.1, 250/252.1 A, 250/330
• US Class Current: 250/252.1
• CPC Class Codes: G01J 1/08 Arrangements of light sources specially adapted for photometry standard sources, also using luminescent or radioactive material
• CPC Class Codes: G01J 2001/0481 Preset integrating sphere or cavity
• CPC Class Codes: G01J 5/53 Reference sources, e.g. standard lamps; Black bodies
• CPC Class Codes: H04N 17/002 for television cameras

Abstract

A test arrangement for assessing the spectral energy distribution-determined response of a night vision device or other electro-optical apparatus. The test arrangement provides a library of spectral energy-distributed test signals or input scenes which may be selected to represent for example typical or extreme conditions expected during field use of the tested night vision device. The test signals originate in an array of energy transducer devices such as light emitting diode elements with each such light emitting diode element proving a limited wavelength component of the wide band composite optical signal received at the input port of the night vision device. Each component signal is arranged to be controlled electrically in presence or absence and also controlled electrically in radiance or intensity according to the needs of the scene being presented; such control is provided by a manual controller or by a programmed digital computer or by other controlling apparatus such as a programmed logic array. The composite test signal may include both infrared and visible components. In addition to control of the composite test signal, other aspects of the performed test such as test scene data storage may also be accomplished in the controller or computer. The disclosed apparatus is especially suited to performance verification of night vision systems in a laboratory environment prior to field use of similar systems. Military and non-military uses are contemplated.

Claims

1. Night vision device spectral energy distribution response evaluation apparatus comprising the combination of:

a plurality of electrical to optical energy transducer devices disposed into a night vision device input port-illuminating first array;

said first array plurality of electrical to optical energy transducer devices including electrical to optical energy transducer devices of selected different optical energy output wavelengths;

a test signal generating, electrical to optical energy transducer device output signal-combining member disposed optically between said first array and an optical input port of said night vision device;

a second array comprised of electrical energy-controlling electronic circuits, each circuit being disposed in electrical energization-determining relationship with one of said electrical to optical energy transducer devices in said first array;

a test signal controlling member connected with each of said electrical energy-controlling electronic circuits for determining an instantaneous electrical current conducting operational status thereof and for selecting successive optical test signals applied to said night vision device input port.

2. The apparatus of claim 1 wherein said electrical to optical energy transducer devices comprise light emitting diodes of incremented wavelength spectral separation.

3. The apparatus of claim 2 wherein said electrical to optical energy transducer devices include light emitting diodes having spectral outputs separated by selected equal wavelength increments.

4. The apparatus of claim 2 wherein said electrical to optical energy transducer devices light emitting diodes have spectral outputs extending between the visible and near infrared ranges of optical energy wavelength.

5. The apparatus of claim 1 wherein said second array electrical energy-controlling electronic circuits include electrical current magnitude-controlling and electrical current commencement and termination-controlling electrical circuits.

6. The apparatus of claim 1 wherein said test signal controlling member consists of one of a manually controllable selection apparatus, an electronic circuit-comprised controller apparatus and a digital computer apparatus.

7. The apparatus of claim 1 wherein said test signal generating, electrical to optical energy transducer device output signal-combining member comprises a spherical optical integration element.

8. The apparatus of claim 1 wherein said second array of electrical energy-controlling electronic circuits includes a plurality of operational amplifier circuits each connected with one of said first array plurality of electrical to optical energy transducer devices.

9. The apparatus of claim 1 wherein said test signal controlling member includes a library of different spectral energy distribution-determining data arrays, each determinative of an energization combination in said electrical to optical energy transducer devices first array.

10. The apparatus of claim 1 wherein said first array of electrical to optical energy transducer devices includes one of a wavelength selective optical filter and a neutral density optical filter for selected of said transducer devices.

11. The apparatus of claim 1 further including a spatial test pattern member located in an optical path intermediate said test signal generating electrical to optical energy transducer device output signal-combining member and said night vision device input port.

12. The method of verifying spectral energy distribution-determined performance of a night vision device comprising the steps of:

forming an array of electrical energy to optical energy transducer elements comprising elements within an input spectral energy distribution band of said night vision device;

generating a night vision device test input signal with energized of said array of electrical energy to optical energy transducer elements, said test input signal including optical energy from array-included transducer elements of selected optical energy output wavelength and radiance level;

controlling wavelength of said test input signal and radiance level of said test input signal by electrically determining one of an illuminated state and a quiescent state for, and an electrical energization level of, each electrical to optical energy transducer element in said array;

exposing an optical input port of said night vision device to said test input signal from said array of electrical energy to optical energy transducer elements;

comparing an output signal of said night vision device, in response to said test input signal, with an expected night vision device output signal for said spectral energy distribution input.

13. The method of claim 12 wherein said array elements comprise light emitting diodes of differing, and successively longer peak radiance wavelength output characteristic.

14. The method of claim 13 wherein said array of electrical energy to optical energy transducer light emitting diodes comprises light emitting diodes of incrementally segregated spectral wavelengths located in the visible and near infrared wavelength electromagnetic spectral regions.

15. The method of claim 12 wherein said controlling step includes initiating, terminating, and limiting an electrical current magnitude, in a flow of electrical energy into each said array element using a solid state electrical control circuit.

16. The method of claim 12 further including the step of combining an output signal from each energized of said array transducer elements into a composite input signal of said night vision device in a spherical diffusing element.

17. Night vision device target spectral energy distribution emulation apparatus comprising the combination of:

means, including a plurality of wavelength-segregated electrical to optical energy transducer elements, for illuminating an input port of a night vision device under test;

said wavelength-segregated electrical to optical energy transducer elements including transducer elements of segregated dominant output wavelengths dispersed incrementally across a selected portion of an input bandpass characteristic of said night vision device input port;

means including an optical energy diffusion spherical member for integrating output optical energy of said plurality of electrical to optical energy transducer elements into a composite optical signal received at said input port of said night vision device;

electrical energy control means, including a plurality of electrical energy-controlling circuits each disposed in electrical energization determining relationship with one of said electrical to optical energy transducer elements, for determining an OFF, ON, and operating intensity status of each of said electrical to optical energy transducer elements in said plurality during generation of each night vision device input port-received composite optical output signal;

output signal selection means connected with each of said electrical energy-controlling circuits for determining spectral content of each successive composite optical output signal presented to said input port of said night vision device.

18. The apparatus of claim 17 wherein said means for evaluating an output response of said night vision device includes means for sensing absence, presence and magnitude of output image elements generated in response to each electrical to optical energy transducer element of said means including a plurality of wavelength-segregated electrical to optical energy transducer elements for illuminating an input port of a night vision device under test.

19. The apparatus of claim 17 wherein said output signal selection means includes a manually operable controlling member.

20. The apparatus of claim 17 wherein said plurality of electrical energy-controlling circuits are electronic circuits and wherein said output signal selection means includes a digital computer connected with said electronic circuits.