Methods and systems for thermal control of an optical source or optical filter in a light detection and ranging (LIDAR) apparatus
A Light Detection And Ranging (LIDAR) apparatus includes an optical emission source configured to emit an optical signal having a wavelength that varies based on a temperature of the optical emission source and/or an optical filter element that is configured to receive a reflection of the optical signal, the optical filter element having a passband that varies based on a temperature of the optical filter element; a thermal controller that is configured to generate a thermal control signal responsive to a temperature measurement related to the optical emission source or the optical filter element; and a temperature control element that is configured to adjust a temperature of the optical emission source or the optical filter element responsive to the thermal control signal.
1 . A Light Detection And Ranging (LIDAR) apparatus, comprising:
an optical emission source configured to emit an optical signal having a wavelength that varies based on a temperature of the optical emission source into a field external to the LIDAR apparatus;
an optical filter element configured to receive a reflection of the optical signal after being reflected from surfaces within the field, the optical filter element having a passband that varies based on a temperature of the optical filter element;
an emission source temperature sensor operatively coupled to measure an ambient temperature of or in close proximity to the optical emission source;
an optical filter temperature sensor operatively coupled to measure an ambient temperature of, or in close proximity to, the optical filter element,
a thermal controller comprising a processor and a non-transitory computer-readable memory having: (i) emission source calibration information stored therein that represents a relationship between light emission wavelength of the optical emission source as a function of temperature values measured by the emission source temperature sensor, and (ii) optical filter calibration information representing a relationship between a passband of the optical filter as a function of temperature values measured by the optical filter temperature sensor, wherein the thermal controller is configured to generate a first thermal control signal responsive to the measured ambient temperature of the optical emission source and the stored emission source calibration information and a second thermal control signal responsive to the measured ambient temperature of the optical filter element and the stored optical filter calibration information;
an emission source temperature control element configured to adjust a temperature of the optical emission source responsive to the first thermal control signal; and
an optical filter temperature control element configured to adjust a temperature of the optical filter element in response to the second thermal control signal.
2 . The LIDAR apparatus of claim 1 , wherein the emission source temperature control element is a heater element or a heat sink.
3 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is a heater element; and
wherein the heater element comprises a transparent conductive oxide or nichrome.
4 . The LIDAR apparatus of claim 3 , wherein the heater element is coated onto the optical filter element.
5 . The LIDAR apparatus of claim 3 , wherein the heater element comprises wires carried on the optical filter element.
6 . The LIDAR apparatus of claim 3 , wherein the transparent conductive oxide comprises indium tin oxide.
7 . The LIDAR apparatus of claim 3 , wherein the heater element directly contacts the optical filter element.
8 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is a heater element; and
wherein the LIDAR apparatus further comprises:
a thermal coupling member that is configured to connect the heater element to the optical filter element.
9 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is a heater element; and
wherein the heater element is positioned in a Fourier plane with respect to the optical filter element.
10 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is a heater element; and
wherein the LIDAR apparatus further comprises:
an optical lens configured to receive a filtered reflection of the optical signal output from the optical filter element;
wherein the optical lens comprises the optical filter element and the heater element is on a barrel of the optical lens.
11 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is a heater element; and
wherein the LIDAR apparatus further comprises:
a monitor circuit that is configured to generate a temperature stabilization detection signal when the temperature of the optical emission source has stabilized; and
wherein the heater element is further configured to adjust a temperature of the optical filter element responsive to the second thermal control signal and the temperature stabilization detection signal.
12 . The LIDAR apparatus of claim 1 , wherein the optical filter temperature control element is
a heater element or a heat sink.
13 . The LIDAR apparatus of claim 2 , wherein the emission source temperature control element is configured to adjust the temperature of the optical emission source; and
wherein the temperature control element is a heater element or a heat sink.
14 . The LIDAR apparatus of claim 1 , further comprising;
an optical lens configured to receive a filtered reflection of the optical signal output from the optical filter element;
wherein the optical lens and the optical filter element are substantially vacated of humidity.
15 . The LIDAR apparatus of claim 1 , wherein a first temperature coefficient of the optical emission source and a second temperature coefficient of the optical filter element have a same sign.
16 . A method of operating a Light Detection And Ranging (LIDAR) apparatus, comprising:
emitting, using an optical emission source, an optical signal having a wavelength that varies based on a temperature of the optical emission source into a field external to the LIDAR apparatus;
receiving, using an optical filter element, a reflection of the optical signal after being reflected from surfaces within the field, the optical filter element having a passband that varies based on a temperature of the optical filter element;
measuring an ambient temperature of, or in close proximity to, the optical emission source with an emission source temperature sensor;
measuring an ambient temperature of, or in close proximity to, the optical filter element with an optical filter temperature sensor;
storing, in a computer-readable memory: (i) emission source calibration information representing a relationship between light emission wavelength of the optical emission source as a function of temperature values measured by the emission source temperature sensor, and (ii) optical filter calibration information representing a relationship between a passband of the optical filter as a function of temperature values measured by the optical filter temperature sensor;
generating, using a thermal controller: (i) a first thermal control signal responsive to the measured ambient temperature of the optical emission source and the stored emission source calibration information, and (ii) a second thermal control signal responsive to the measured ambient temperature of the optical filter and the stored optical filter calibration information;
adjusting, using an emission source temperature control element, a temperature of the optical emission source responsive to the first thermal control signal; and
adjusting, using an optical filter temperature control element, a temperature of the optical filter responsive to the second thermal control signal.
17 . The method of claim 16 , wherein the emission source temperature control element is a heater element or a heat sink.
18 . The method of claim 16 ,
wherein the optical filter temperature control element is a heater element or a heat sink.