System for emulating an environment for testing a frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) system
A system for emulating an over-the-air environment for testing a light detection and ranging (LiDAR) unit under test (UUT). The system may comprise a lens system that receives light from the LiDAR UUT and a plurality of optical processing chains. The system may generate light into free space based on the optical signals processed by each chain. The system may process received light optically to maintain coherence with light received from the LiDAR unit under test and may process all points in a LiDAR image simultaneously. The system may operate to emulate an over-the-air environment for a time-of-flight LiDAR UUT, a frequency modulated continuous wave (FMCW) LiDAR UUT, and/or a flash LiDAR UUT.
1 . A method for emulating an over-the-air environment for testing a light detection and ranging (LiDAR) unit under test (UUT), the method comprising:
receiving, by a plurality of optical processing chains, a plurality of laser pulses from one or more lasers of the LiDAR UUT, wherein each optical processing chain comprises an optical fiber configured to receive a distinct subset of the plurality of laser pulses;
for each of the optical processing chains, modulating the received laser pulses to emulate the over-the-air environment by implementing:
in-phase quadrature (IQ) frequency modulation; and
optical amplitude modulation; and
transmitting the modulated laser pulses to the LiDAR UUT.
2 . The method of claim 1 ,
wherein the LiDAR UUT comprises a frequency modulated continuous wave (FMCW) LiDAR UUT.
3 . The method of claim 1 ,
wherein the plurality of laser pulses comprise a linear frequency up-sweep followed by a linear frequency down-sweep,
wherein implementing the IQ frequency modulation comprises:
shifting the linear frequency up-sweep in a same direction as the linear frequency down-sweep to emulate a Doppler shift in the over-the-air environment; and
shifting the linear frequency up-sweep in an opposite direction as the linear frequency down-sweep to emulate a time delay in the over-the-air environment.
4 . The method of claim 1 ,
wherein each distinct subset of the plurality of laser pulses comprises laser pulses from a distinct laser of the LiDAR UUT,
wherein each laser of the LiDAR UUT sweeps over a distinct portion of the field of view of the LiDAR UUT.
5 . The method of claim 1 ,
wherein implementing optical amplitude modulation comprises selectively attenuating and/or amplifying the received laser pulses to emulate reflectivity and path loss at locations being emulated in the over-the-air environment.
6 . The method of claim 1 ,
wherein modulating the received laser pulses is performed optically to maintain coherence between the received laser pulses and the modulated laser pulses.
7 . The method of claim 1 ,
wherein the plurality of optical processing chains concurrently modulate their respective received laser pulses.
8 . The method of claim 1 , the method further comprising:
receiving frequency modulation values and amplitude modulation values from a LiDAR image generator for each point in a point cloud of the over-the-air environment,
wherein said implementing IQ frequency modulation and optical amplitude modulation is performed based on the frequency modulation values and the amplitude modulation values.
9 . The method of claim 1 ,
wherein the plurality of laser pulses is received by the plurality of optical processing chains via a lens system configured to focus respective distinct subsets of the plurality of laser pulses onto respective optical processing chains of the plurality of optical processing chains.
10 . A system for emulating an over-the-air environment for testing a light detection and ranging (LiDAR) unit under test (UUT), the system comprising:
a lens system configured to receive light from the LiDAR UUT;
a plurality of optical processing chains coupled to the lens system, wherein each optical processing chain comprises:
an optical fiber coupled to the lens system and configured to receive laser pulses from the LiDAR UUT through the lens system;
an in-phase quadrature (IQ) frequency modulator configured to modulate a frequency of the received laser pulses;
an optical time delay configured to time delay the received laser pulses; and
an optical amplitude modulator configured to modulate an amplitude of the received laser pulses,
wherein each optical processing chain is configured to transmit the frequency shifted, time delayed and amplitude modulated laser pulses to the LiDAR UUT, and wherein the frequency shifted, time delayed and amplitude modulated laser pulses emulate the over-the-air environment.
11 . The system of claim 10 , wherein the system is further configured to:
perform one or more measurements on light received from the LiDAR UUT, wherein the one or more measurements comprise one or more of:
a laser line width measurement;
a chirp linearity measurement;
an optical spectrum analyzer measurement;
an optical power measurement; and
a pulse width measurement.
12 . The system of claim 10 ,
wherein the LiDAR UUT comprises a frequency modulated continuous wave (FMCW) LiDAR UUT.
13 . The system of claim 10 ,
wherein the received laser pulses comprise a linear frequency up-sweep followed by a linear frequency down-sweep,
wherein modulating the frequency of the received laser pulses comprises:
shifting the linear frequency up-sweep in a same direction as the linear frequency down-sweep to emulate a Doppler shift in the over-the-air environment.
14 . The system of claim 10 ,
wherein each optical fiber receives a distinct subset of laser pulses received from a distinct laser of a plurality of lasers of the LiDAR UUT,
wherein each laser of the plurality of lasers sweeps over a distinct portion of the field of view of the LiDAR UUT.
15 . The system of claim 14 ,
wherein each laser of the plurality of lasers sweeps over a single line of the field of view of the LiDAR UUT, and
wherein the lens system is configured to focus light received along each line into respective points.
16 . The system of claim 10 ,
wherein modulating the amplitude of the received laser pulses comprises selectively attenuating and/or amplifying the received laser pulses to emulate reflectivity and path loss at a locations being emulated in the over-the-air environment.
17 . The system of claim 10 ,
wherein delaying and modulating the frequency and the amplitude and of the received laser pulses is performed optically to maintain coherence between the received laser pulses and the modulated laser pulses.
18 . The system of claim 10 ,
wherein the plurality of optical processing chains concurrently modulate their respective received laser pulses.
19 . The system of claim 10 , the system further comprising:
a LiDAR image generator coupled to the plurality of optical processing chains, wherein the LiDAR image generator is configured to provide frequency modulation, time delay and amplitude modulation values to the plurality of optical processing chains for each point in a point cloud of the over-the-air environment,
wherein the LiDAR image generator is user programmable to produce frequency modulation, time delay and amplitude modulation values corresponding to different over-the-air environments, and
wherein delaying and modulating the frequency and amplitude of the received laser pulses is performed based on the frequency modulation, time delay, and amplitude modulation values.
20 . The system of claim 10 ,
wherein the frequency shifted, time delayed and amplitude modulated laser pulses are transmitted to the LiDAR UUT through the lens system.