Dual-band semi-active laser system

Patent metadata

Field	Value
Publication number	US-9939231-B2
Application number	US-201615001833-A
Country	US
Kind code	B2
Filing date	Jan 20, 2016
Priority date	Jan 20, 2016
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A dual-band semi-active laser (SAL) sensing system incorporating a dual-passband filter. According to one example, a semi-active laser sensing system includes a detector assembly and an aperture lens. The SAL sensing system further comprises a dual-passband filter having a stopband, a first passband and a second passband, the first and second passbands being distinct and non-overlapping and spectrally separated from one another by a portion of the stopband, the filter being configured to receive the electromagnetic radiation from the aperture lens and to filter the electromagnetic radiation to pass a first wavelength range within the first passband and a second wavelength range within the second passband. The SAL sensing system further includes a lens assembly configured to receive the first and second wavelength ranges from the filter and to focus the first and second wavelength ranges onto the detector assembly.

First claim

What is claimed is:

1. A semi-active laser (SAL) sensing system for a guidance system, the SAL sensing system comprising:
a detector assembly;
an aperture lens configured to receive electromagnetic radiation;
a dual-passband filter having a stopband, a first passband, and a second passband, the first and second passbands being distinct and non-overlapping and spectrally separated from one another by a portion of the stopband, the filter being configured to receive the electromagnetic radiation from the aperture lens and to filter the electromagnetic radiation to pass a first wavelength range within the first passband and a second wavelength range within the second passband;
an electromagnetic interference (EMI) shield including a microgrid pattern formed from a conductive material and disposed on the filter, the EMI shield being transmissive to the first and second wavelength ranges and being configured to suppress incident electromagnetic interference;
a diffuser integrated with the filter and the EMI shield, the diffuser configured to diffuse the first and second wavelength ranges; and
a lens assembly configured to receive the first and second wavelength ranges from the filter and to focus the first and second wavelength ranges onto the detector assembly.

2. The SAL sensing system of claim 1 wherein the EMI shield is at least 90% transmissive to the first and second wavelength ranges.

3. The SAL sensing system of claim 2 wherein the microgrid pattern is photolithographically deposited.

4. The SAL sensing system of claim 2 wherein the microgrid pattern is randomized.

5. The SAL sensing system of claim 2 wherein the microgrid pattern has a linewidth in a range of about 5 μm to about 6 μm.

6. The SAL sensing system of claim 2 wherein the conductive material is gold.

7. The SAL sensing system of claim 1 wherein the first passband is centered at approximately 1064 nm and the second passband is centered at approximately 1550 nm.

8. The SAL sensing system of claim 7 wherein the stopband extends from approximately 700 nm to a lower limit of the first passband, between the first and second passbands, and from an upper limit of the second passband to approximately 1900 nm.

9. The SAL sensing system of claim 1 wherein the lens assembly includes at least two lenses, each made from a material selected from the group consisting of glass, zinc sulfide, borosilicate, and polyetherimide.

10. The SAL sensing system of claim 9 wherein at least one of the two lenses has an aspheric surface figure.

11. The SAL sensing system of claim 1 wherein the detector assembly includes a quad-cell sensor having a spectral response that includes the first and second wavelength ranges.

12. The SAL sensing system of claim 1 wherein the diffuser is positioned between the filter and the lens assembly.

13. The SAL sensing system of claim 12 further comprising an anti-reflective coating deposited over the microgrid pattern disposed on the filter.

14. A semi-active laser (SAL) sensing system for a guidance system, the SAL sensing system comprising:
a detector assembly including a photo-sensitive sensor having a detection band including a first wavelength range;
an aperture lens configured to receive electromagnetic radiation;
a dual-band filter having a first passband and a second passband, the first and second passbands being distinct and non-overlapping, the dual-band filter being configured to receive the electromagnetic radiation from the aperture lens and to filter the electromagnetic radiation to pass a second wavelength range within the first passband and a third wavelength range within the second passband, and to block from reaching the detector assembly the electromagnetic radiation that is within the detection band and outside the first and second passbands;
an electromagnetic interference (EMI) shield transmissive to the second and third wavelength ranges, the EMI shield including a microgrid pattern formed from a conductive material and disposed on the dual-band filter, the EMI shield being configured to suppress incident electromagnetic interference;
a diffuser integrated with the dual-passband filter and the EMI shield, the diffuser configured to diffuse the second and third wavelength ranges; and
a lens assembly configured to receive the second and third wavelength ranges from the filter and to focus the second and third wavelength ranges onto the detector assembly.

15. The SAL sensing system of claim 14 wherein the microgrid pattern has a linewidth in a range of about 5 μm to about 6 μm.

16. The SAL sensing system of claim 15 wherein the conductive material is gold.

17. The SAL sensing system of claim 14 wherein the first passband is centered at approximately 1064 nm and the second passband is centered at approximately 1550 nm.

18. The SAL sensing system of claim 14 further comprising an anti-reflective coating deposited over the microgrid pattern disposed on the filter.

Assignees

• Raytheon Co

Inventors

• Roncone Ronald L
• Lickson Raymond S
• Peterson Eric X

Classifications

• G02B5/285

  comprising deposited thin solid films (G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361) · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B5/0278

  used in transmission · CPC title

• F41G7/2293

  using electromagnetic waves other than radio waves · CPC title

• F41G7/226 Primary

  Semi-active homing systems, i.e. comprising a receiver and involving auxiliary illuminating means, e.g. using auxiliary guiding missiles · CPC title