Active multi-spectral sensor

Patent metadata

Field	Value
Publication number	US-9903757-B1
Application number	US-201615275172-A
Country	US
Kind code	B1
Filing date	Sep 23, 2016
Priority date	Sep 25, 2015
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A sensor includes a plurality of transmitter units, a photodetector, and an optical system coupled to the plurality of transmitter units and the photodetector. Each of the transmitter units simultaneously transmits a light beam having a plurality of wavelengths, the optical system directs the light beam from each of the transmitter units onto a same illuminated spot on a probed surface, and the optical system collects light from the same illuminated spot and directs the light to the photodetector.

First claim

What is claimed is:

1. A sensor comprising:
a plurality of laser transmitter units, wherein each of the plurality of laser transmitter units is configured to transmit a light beam having a plurality of wavelengths;
a photodetector; and
an optical system coupled to the plurality of laser transmitter units and the photodetector;
wherein the optical system directs the light beam from each of the laser transmitter units onto a same illuminated spot on a probed surface; and
wherein the optical system collects light from the same illuminated spot and directs the light to the photodetector.

2. The sensor of claim 1 further comprising:
an aperture;
wherein the optical system directs the light beam from each respective laser transmitter unit onto a portion of the aperture different from portions of the aperture onto which other light beams from other laser transmitter units are directed.

3. The sensor of claim 2 :
wherein the optical system directs the light beams from different portions of the aperture to the same illuminated spot on the probed surface; and
further comprising a beam steering device coupled to the optical system for moving a spatial position of the same illuminated spot on the probed surface, and for directing the collected light to the photodetector.

4. The sensor of claim 3 :
wherein the beam steering device comprises at least one single two-axis-motion fast-steering mirror, or at least a pair of one-axis-motion galvo mirrors.

5. The sensor of claim 1 :
wherein each of the transmitted wavelengths of the plurality of wavelengths transmitted by each laser transmitter unit is modulated by a radio frequency that is unique for each transmitted wavelength; and
further comprising a channelizer coupled to the photodetector, the channelizer having a plurality of receiver outputs;
wherein each respective receiver output is derived using the radio frequency that is unique for each transmitted wavelength; and
wherein each respective receiver output corresponds to one of the transmitted wavelengths.

6. The sensor of claim 1 wherein each transmitted wavelength comprises a long-wave infrared (LWIR) wavelength, a mid-wave infrared (MWIR) wavelength, or a short-wave infrared (SWIR) wavelength.

7. A multi-spectral sensor comprising:
a plurality of laser devices each comprising:
a laser section having a light output;
an optical amplifier coupled to the laser section; and
an optical modulator coupled to the optical amplifier;

wherein the light output of each respective laser section of the plurality of laser devices has a respective wavelength that is different from a wavelength of the light output from each other laser section of the plurality of laser devices;
wherein each respective optical modulator of the plurality of laser devices is configured to modulate the light output of a respective laser section with a respective modulation frequency that is different from a modulation frequency of each other optical modulator of the plurality of laser devices; and
wherein the multi-spectral sensor is configured so that the plurality of laser devices simultaneously transmit a plurality of light beams, each respective light beam modulated with a respective modulation frequency; and
a photodetector for detecting received light; and
a channelizer coupled to the photodetector, the channelizer having a plurality of receiver outputs;
wherein each respective receiver output of the plurality of receiver outputs is derived using one of the respective modulation frequencies; and
wherein each respective receiver output corresponds to one of the respective wavelengths.

8. The multi-spectral sensor of claim 7 :
wherein each respective laser section comprises a distributed feedback laser having a grating of a different grating period, or wherein each respective laser section comprises a distributed feedback laser having a different drive current.

9. The multi-spectral sensor of claim 7 further comprising:
a plurality of reference light outputs coupled between the plurality of laser devices and the channelizer;
wherein each respective reference light output has one of the respective wavelengths.

10. The multi-spectral sensor of claim 7 wherein each wavelength comprises a long-wave infrared (LWIR) wavelength, a mid-wave infrared (MWIR) wavelength, or a short-wave infrared (SWIR) wavelength.

11. The multi-spectral sensor of claim 7 wherein each modulation frequency is a radio frequency.

12. The multi-spectral sensor of claim 7 wherein the plurality of laser device comprises:
at least two first laser devices located adjacent to each other and separated by a first spatial spacing, wherein the at least two first laser devices each have a different wavelength, and wherein the different wavelengths of the at least two first laser devices are different by a first increment; and
at least two second laser devices located adjacent to each other and separated by a second spatial spacing, wherein the at least two second laser devices each have a different wavelength, and wherein the different wavelengths of the at least two second laser devices are different by a second increment;
wherein the first spacing and the second spacing are equal;
wherein the wavelengths of the two first laser devices are longer than the wavelengths of the second two laser devices; and
wherein first increment is smaller than the second increment.

13. The multi-spectral sensor of claim 7 further comprising:
an optical system for directing the plurality of light beams onto a same illuminated spot on a probed surface; and
a beam steering device coupled to the optical system for moving a spatial position of the same illuminated spot on the probed surface, and for directing the received light to the photodetector.

14. The multi-spectral sensor of claim 7 wherein the plurality of laser devices further comprises:
a laser array controller comprising:
a laser wavelength control coupled to each laser section for tuning the wavelength of each respective laser section;
an output level adjust coupled to each optical amplifier;
a radio frequency control coupled to each optical modulator.

15. The multi-spectral sensor of claim 7 further comprising:
at least a first substrate and a second substrate;
a first plurality of laser devices of the plurality of laser devices on the first substrate;
a second plurality of laser devices of the plurality of laser devices on the second substrate;
a top layer for providing interconnects for the first and second plurality of laser devices, wherein the first substrate and the second substrate are on the top layer;
a heat spreader coupled to the top layer; and
a cold plate coupled to the heat spreader.

16. The multi-spectral sensor of claim 13 :
wherein the photodetector comprises a first photodetector and a second photodetector; and
wherein the optical system and the beam steering device direct the received light to the first photodetector and the second photodetector.

17. The multi-spectral sensor of claim 13 :
wherein the beam steering device comprises a single two-axis-motion fast-steering mirror, or a pair of one-axis-motion galvo mirrors.

18. A method of sensing comprising:
simultaneously transmitting from each of a plurality of laser transmitter units a light beam, wherein each light beam comprises a plurality of wavelengths;
directing the light beam from each of the laser transmitter units onto a same illuminated spot on a probed surface using an optical system;
collecting light from the same illuminate

Assignees

• Hrl Lab Llc

Inventors

• Yap Daniel
• Neff Brian

Classifications

• G01N2021/399

  Diode laser · CPC title

• G01N21/94

  Investigating contamination, e.g. dust (G01N21/85 takes precedence) · CPC title

• G01N2201/067

  Electro-optic, magneto-optic, acousto-optic elements · CPC title

• G01N21/39

  using tunable lasers · CPC title

• G01N21/35

  using infrared light (G01N21/39 takes precedence) · CPC title