Rotating compact light ranging system
A light ranging system including a shaft having a longitudinal axis; a light ranging device configured to rotate about the longitudinal axis of the shaft, the light ranging device including a light source configured to transmit light pulses to objects in a surrounding environment, and detector circuitry configured to detect reflected portions of the light pulses that are reflected from the objects in the surrounding environment and to compute ranging data based on the reflected portion of the light pulses; a base subsystem that does not rotate about the shaft; and an optical communications subsystem configured to provide an optical communications channel between the base subsystem and the light ranging device, the optical communications subsystem including one or more turret optical communication components connected to the detector circuitry and one or more base optical communication components connected to the base subsystem.
1. An image sensing device comprising:
a lens tube having a back wall and a tubular sidewall extending away from the back wall to define a front aperture opposite the back wall;
a lens housing disposed within the lens tube and coupled to an interior surface of the tubular sidewall;
a bulk lens system mechanically coupled to the lens housing and configured to focus light received through the front aperture to an image plane, the bulk lens system comprising a plurality of lenses; and
an array of photosensors coupled to the back wall of the lens tube at the image plane of the bulk lens system, the array of photosensors configured to receive light from the bulk lens system;
wherein, as the image sensing device is exposed to increasing temperatures, the lens housing elongates shifting the image plane in a first direction towards the back wall of the lens tube while the lens tube expands shifting the image plane in a second direction, opposite the first direction, to compensate for elongation of the lens housing.
2. The image sensing device set forth in claim 1 further comprising circuitry configured to compute ranging data based on reflected portions of light pulses detected by the array of photosensors.
3. The image sensing device set forth in claim 1 wherein the bulk lens system is an image-space telecentric lens system.
4. The image sensing device set forth in claim 1 further comprising a temperature sensor and a heating element operatively coupled to heat the bulk lens system in response to the temperature sensor.
5. The image sensing device set forth in claim 1 wherein:
the lens housing is coupled to the lens tube at a first interface;
the lens housing is made form a first material and the lens tube is made from a second material;
a coefficient of thermal expansion (CTE) of the first material, a CTE of the second material and the first interface are chosen such that the image plane remains approximately coincident with the array of photosensors over a temperature range of at least 20 degrees C. to 70 degrees C.
6. The image sensing device set forth in claim 5 wherein the temperature range is from −5 degrees C. to 70 degrees C.
7. The image sensing device set forth in claim 1 wherein the lens system has an f-number equal to or less than 2.4 and equal to or greater than 0.7.
8. The image sensing device of claim 1 wherein the plurality of lenses comprises a first lens, a second lens, and a third lens mounted in the lens housing; wherein at least one of the first lens and the second lens is plastic and the third lens is glass.
9. The image sensing device of claim 8 wherein the plurality of lenses further comprises a fourth lens.
10. A light ranging device comprising:
an optical transmitter comprising an image-space telecentric bulk transmitter lens system and a plurality of transmitter channels, each transmitter channel including a light emitter configured to generate and transmit pulses of narrowband light through the bulk transmitter optic into a field external to the light ranging system; and
an optical receiver comprising:
a lens tube having a back wall and a tubular sidewall extending away from the back wall to define a front aperture opposite the back wall;
a lens housing disposed within the lens tube and coupled to an interior surface of the tubular sidewall;
an image-space telecentric bulk receiver lens system mechanically coupled to the lens housing and configured to focus light received through the front aperture to an image plane, the image-space telecentric bulk receiver lens system comprising a plurality of lenses; and
an array of photosensors coupled to the back wall of the lens tube at the image plane of the image-space telecentric bulk receiver lens system, the array of photosensors configured to receive light from the image-space telecentric bulk receiver lens system;
wherein, as the light ranging device is exposed to increasing temperatures, the lens housing elongates shifting the image plane in a first direction towards the back wall of the lens tube while the lens tube expands shifting the image plane in a second direction, opposite the first direction, to compensate for elongation of the lens housing.
11. The light ranging device set forth in claim 10 further comprising circuitry configured to compute ranging data based on reflected portions of light pulses detected by the array of photosensors.
12. The light ranging device set forth in claim 10 further comprising a temperature sensor and a heating element operatively coupled to heat the bulk lens system in response to the temperature sensor.
13. The light ranging device set forth inset forth in claim 10 wherein:
the lens housing is coupled to the lens tube at a first interface;
the lens housing is made form a first material and the lens tube is made from a second material;
a coefficient of thermal expansion (CTE) of the first material, a CTE of the second material and the first interface are chosen such that the image plane remains approximately coincident with the array of photosensors over a temperature range of at least 20 degrees C. to 70 degrees C.
14. The light ranging device set forth in claim 10 wherein each emitter comprises a plurality of vertical cavity surface emitting lasers (VCSELs).
15. The light ranging device set forth in claim 10 wherein each photosensor comprises a plurality of single photon avalanche diodes (SPADs).
16. The light ranging device set forth in claim 10 wherein the array of photosensors is planar and wherein the optical receiver further comprises a micro-optical channel for each photosensor in the array of photosensors, the micro-optical channel including an aperture layer positioned at the image plane, a micro-lens layer and a filter layer.
17. A light ranging device comprising:
an enclosure having an optically transparent window extending fully around an outer periphery of the enclosure;
a light transmission module disposed within the enclosure and comprising:
a first lens tube having a first back wall and a first tubular sidewall extending away from the first back wall to define a first front aperture opposite the first back wall;
a first lens housing disposed within the first lens tube and coupled to an interior surface of the first tubular sidewall;
an image-space telecentric bulk transmitter lens system mechanically coupled to the first lens housing and configured to focus light received through the first front aperture to a first image plane, the image-space telecentric bulk transmitter lens system comprising a first plurality of lenses; and
an array of light emitters coupled to the back wall of the lens tube at the image plane of the image-space telecentric bulk transmitter lens system, the array of light emitters configured to generate and transmit pulses of narrowband light through the image-space telecentric bulk transmitter lens system and through the optically transparent window into a field external to the light ranging system; and
a light sensing module disposed within the enclosure and comprising:
a second lens tube having a second back wall and a second tubular sidewall extending away from the second back wall to define a second front aperture opposite the second back wall;
a second lens housing disposed within the second lens tube and coupled to an interior surface of the second tubular sidewall;
an image-space telecentric bulk receiver lens system mechanically coupled to the second lens housing and configured to focus light received through the second front aperture to a second image plane, the image-space telecentric bulk receiver lens system comprising a second plurality of lenses; and
an array of photosensors coupled to the second back wall of the second lens tube at the second image plane of the image-space telecentric bulk receiver lens system, the array of photosensors configured to receive light from the image-space telecentric bulk receiver lens system;
wherein, as the light ranging device is exposed to increasing temperatures:
the first lens housing elongates shifting the first image plane in a first direction towards the back wall of the first lens mount while the first lens mount expands shifting the image plane in a second direction, opposite the first direction, to compensate for elongation of the first lens housing; and
the second lens housing elongates shifting the second image plane in the first direction towards the back wall of the second lens mount while the second lens mount expands shifting the image plane in the second direction, opposite the first direction, to compensate for elongation of the second lens housing.
18. The light ranging device set forth in claim 17 wherein the transmission module and the light sensing module are disposed adjacent to each other in a side-by-side arrangement.
19. The light ranging device set forth in claim 17 further comprising circuitry configured to compute ranging data based on reflected portions of light pulses detected by the array of photosensors.
20. The light ranging device set forth in claim 17 further comprising a temperature sensor and a heating element operatively coupled to heat the bulk lens system in response to the temperature sensor.