Range imaging devices and methods
View Patent ↗An array of laser diode emitters is used as an illumination source for a range imaging system. The laser diode emitters are disposed on a common substrate. When one of the emitters fails, the remaining emitters emit enough light to meet the output optical power specification. The emitters can be disposed with a tight spacing. The tight spacing facilitates packaging of the entire array into a compact single package on a common heat sink.
1. A laser diode array comprising:
a semiconductor substrate; and
a plurality of laser diode emitters on the semiconductor substrate,
wherein the plurality of the laser diode emitters have a non-uniform emitter spacing along the semiconductor substrate, the emitter spacing decreasing from a middle of the laser diode array to a first edge of the semiconductor substrate and decreasing from the middle of the laser diode array to a second edge of the semiconductor substrate, to reduce thermal gradients and associated emitter-to-emitter wavelength spread during operation of the laser diode array.
2. The laser diode array of claim 1 , wherein
the emitter spacing at the middle of the laser diode array is smaller than 40 micrometers, and
the emitter spacing at the first edge of the semiconductor substrate and the second edge of the semiconductor substrate is larger than 10 micrometers.
3. The laser diode array of claim 1 , wherein a width between the first edge of the semiconductor substrate and the second edge of the semiconductor substrate is less than three hundred micrometers.
4. The laser diode array of claim 1 , wherein a total quantity of the plurality of the laser diode emitters is at least five.
5. The laser diode array of claim 1 , further comprising:
a heat sink, wherein the semiconductor substrate is connected to the heat sink for removing heat from the semiconductor substrate during operation of the laser diode array.
6. The laser diode array of claim 5 , further comprising:
a package in which the heat sink, the semiconductor substrate, and the plurality of the laser diode emitters are disposed.
7. The laser diode array of claim 1 for emitting light at a wavelength between 900 nm and 1100 nm,
wherein the plurality of the laser diode emitters comprise at least one of AlGaAs, GaInP, or GaAsInP, and
wherein the semiconductor substrate comprises GaAs.
8. The laser diode array of claim 1 for emitting light at a wavelength between 1300 nm and 1600 nm,
wherein the plurality of the laser diode emitters comprise at least one of InGaAsP or InGaAlAs, and
wherein the semiconductor substrate comprises InP.
9. The laser diode array of claim 1 , wherein the plurality of the laser diode emitters are single spatial mode emitters.
10. The laser diode array of claim 1 , wherein the plurality of the laser diode emitters have a width of no more than 10 micrometers.
11. The laser diode array of claim 1 , wherein a width of the laser diode array is less than one millimeter.
12. The laser diode array of claim 1 , wherein the plurality of the laser diode emitters are electrically connected in parallel.
13. A light source comprising the laser diode array of claim 1 and a controller operationally coupled thereto and configured to:
monitor output optical power of the laser diode array; and
increase an electrical current supplied to the laser diode array based on determining a drop of output optical power due to a failure of at least one of the plurality of the laser diode emitters.
14. A method comprising:
supplying an electrical current to a laser diode array to generate an output beam having an output optical power,
wherein the laser diode array comprises a semiconductor substrate and a plurality of laser diode emitters on the semiconductor substrate,
wherein the plurality of the laser diode emitters have a non-uniform emitter spacing along the semiconductor substrate, the emitter spacing decreasing from a middle of the laser diode array to a first edge of the semiconductor substrate and decreasing from the middle of the laser diode array to a second edge of the semiconductor substrate;
monitoring the output optical power of the laser diode array;
determining, based on monitoring the output optical power, a drop of the output optical power due to a failure of at least one of the plurality of the laser diode emitters of the laser diode array; and
increasing, based on determining the drop of the output optical power, an electrical current supplied to the laser diode array.
15. The method of claim 14 , wherein
the emitter spacing at the middle of the laser diode array is smaller than 40 micrometers, and
the emitter spacing at the first edge of the semiconductor substrate and the second edge of the semiconductor substrate is larger than 10 micrometers.
16. The method of claim 14 , wherein the plurality of the laser diode emitters are single spatial mode emitters.
17. The method of claim 14 , wherein the plurality of the laser diode emitters are electrically connected in parallel.
18. The method of claim 14 , wherein
the plurality of the laser diode emitters comprise at least one of AlGaAs, GaInP, or GaAsInP, and
the semiconductor substrate comprises GaAs.
19. The method of claim 14 , wherein
the plurality of the laser diode emitters comprise at least one of InGaAsP or InGaAlAs, and
the semiconductor substrate comprises InP.
20. The method of claim 14 , wherein at least one of:
a width between the first edge of the semiconductor substrate and the second edge of the semiconductor substrate is less than three hundred micrometers, or
the plurality of the laser diode emitters have a width of no more than 10 micrometers.