Test station to characterize the emission of a LiDAR
N. F. Cunha, Manuel J. L. F. Rodrigues, F. Ferreira, J. Viana-Gomes, J. M. M. Linhares, S. Franco, F. Oliveira, N. Soares, M. I. Vasilevskiy, and L. Rebouta
N. F. Cunha,1,*
Manuel J. L. F. Rodrigues,2
F. Ferreira,1
J. Viana-Gomes,2
J. M. M. Linhares,2
S. Franco,2
F. Oliveira,2
N. Soares,3
M. I. Vasilevskiy,2
and L. Rebouta1
1Physics Centre of Minho and Porto Universities, University of Minho, Azurém, 4800-058 Guimarães, Portugal
2Physics Center of Minho and Porto Universities, University of Minho, Gualtar, 4710-057 Braga, Portugal
3Bosch Car Multimédia Portugal, S.A., 4701-970 Braga, Portugal
N. F. Cunha, Manuel J. L. F. Rodrigues, F. Ferreira, J. Viana-Gomes, J. M. M. Linhares, S. Franco, F. Oliveira, N. Soares, M. I. Vasilevskiy, and L. Rebouta, "Test station to characterize the emission of a LiDAR," Appl. Opt. 63, 17-29 (2024)
A test station setup devised to measure the emission characteristics and beam propagation parameters of a light detection and ranging (LiDAR) system is presented. The main blocks of the station to measure the accessible emission, wavelength peak and FWHM, pulse duration, pulse repetition rate, horizontal and vertical angular resolution, field of view, beam propagation factor ${{\rm M}^2}$, beam waist size, waist location, and divergence are described. The performance of this test station was demonstrated using a commercial spinning LiDAR, a Velodyne VLP-16, which successfully enables these measurements for a laser beam with a wavelength of 913 nm.
Alexander Munk, Sarah Scheuer, Michael Strotkamp, Bernd Jungbluth, Jan Froh, Thorben Mense, Alsu Mauer, and Josef Höffner Appl. Opt. 62(33) 8732-8740 (2023)
Gilles Larchevêque, Ioan Balin, Remo Nessler, Philippe Quaglia, Valentin Simeonov, Hubert van den Bergh, and Bertrand Calpini Appl. Opt. 41(15) 2781-2790 (2002)
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
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Summary of the Results Obtained for the Horizontal Angular Resolution Measurements Using Lasers ID 1 and ID 14, for Different Rotation Frequencies
Rotation Frequency (Hz)
Angular Resolution (°)
20
15
10
Table 6.
Summary of the Results Obtained for the Vertical Angular Resolution Measurementsa
Laser ID
Angular Resolution (°)
5-3
3-1
1-14
14-12
12-10
Average (°)
Standard deviation (°)
2.03
0.03
The laser numbering is in accordance with the numbering mentioned in the VPL-16 manual [7].
Table 7.
Results Estimated for the Horizontal Angular Resolution Using the Setup, Considering Different Rotation Frequencies
Rotation Frequency (Hz)
Angular Resolution (°)
20
15
10
5
Table 8.
Accessible Emission During a Rotation Cycle, Considering the Required Time to Scan the 7 mm Aperture and Accessible Emission Limits for Corresponding Time Intervalsa
Frame Rate (Hz)
Power at Position of the Highest Average Power (µW)
Rotation Period (s)
AE during a Cycle (J)
Time to Scan 7 mm Aperture (s)
AEL (J) Class 1
5
57.3
0.2
10
68.0
0.1
15
63.3
0.0667
20
69.0
0.05
Rotation frequencies of 5 Hz, 10 Hz, 15 Hz, and 20 Hz were considered, and the power meter was located at 100 mm from the LIDAR spin axis. Accessible emission, AE; accessible emission limits, AEL.
Table 9.
Summary of the Results of the Measures Obtained from the Velodyne VLP-16 Using the Setup Prototype Comparing against the Data Specified by the Manufacturer [7]
Parameters
Specified by Manufacturer
Measured
Effective pulse duration (ns)
6
Pulse FWHM (ns)
-
Pulse repetition period (µs)
55.296
Frame period (at 10 Hz) (s)
0.1
0.1
Laser class
Class 1 Eye Safe
Class 1 Eye Safe
Vertical angular resolution (°)
2
Horizontal angular resolution for 10 Hz (°)
0.2
Horizontal angular resolution for 20 Hz (°)
0.4
Vertical FoV (°)
30
Laser wavelength (nm)
903 (min/max 896/910 nm)
Laser peak FWHM (nm)
-
Full horizontal divergence (mrad) (average of 4 lasers)
3
Full vertical divergence (mrad) (average of 4 lasers)
1.5
Horizontal (average of 4 lasers)
-
Vertical (average of 4 lasers)
-
Horizontal beam diameter at sensor ring lens (mm)
12.7
Vertical beam diameter at sensor ring lens (mm)
9.5
Horizontal laser spot diameter at 5 m (mm)
26.4
Vertical laser spot diameter at 5 m (mm)
17.0
Tables (9)
Table 1.
List of Equipment and Optical Components Used in Different Setups of the Test Station and Illustrated in Fig. 1
Setup
Equipment and Components
LiDAR alignment
Two irises I4, I5
Time dependence and optical spectrum of a LiDAR emission
Summary of the Results Obtained for the Horizontal Angular Resolution Measurements Using Lasers ID 1 and ID 14, for Different Rotation Frequencies
Rotation Frequency (Hz)
Angular Resolution (°)
20
15
10
Table 6.
Summary of the Results Obtained for the Vertical Angular Resolution Measurementsa
Laser ID
Angular Resolution (°)
5-3
3-1
1-14
14-12
12-10
Average (°)
Standard deviation (°)
2.03
0.03
The laser numbering is in accordance with the numbering mentioned in the VPL-16 manual [7].
Table 7.
Results Estimated for the Horizontal Angular Resolution Using the Setup, Considering Different Rotation Frequencies
Rotation Frequency (Hz)
Angular Resolution (°)
20
15
10
5
Table 8.
Accessible Emission During a Rotation Cycle, Considering the Required Time to Scan the 7 mm Aperture and Accessible Emission Limits for Corresponding Time Intervalsa
Frame Rate (Hz)
Power at Position of the Highest Average Power (µW)
Rotation Period (s)
AE during a Cycle (J)
Time to Scan 7 mm Aperture (s)
AEL (J) Class 1
5
57.3
0.2
10
68.0
0.1
15
63.3
0.0667
20
69.0
0.05
Rotation frequencies of 5 Hz, 10 Hz, 15 Hz, and 20 Hz were considered, and the power meter was located at 100 mm from the LIDAR spin axis. Accessible emission, AE; accessible emission limits, AEL.
Table 9.
Summary of the Results of the Measures Obtained from the Velodyne VLP-16 Using the Setup Prototype Comparing against the Data Specified by the Manufacturer [7]
Parameters
Specified by Manufacturer
Measured
Effective pulse duration (ns)
6
Pulse FWHM (ns)
-
Pulse repetition period (µs)
55.296
Frame period (at 10 Hz) (s)
0.1
0.1
Laser class
Class 1 Eye Safe
Class 1 Eye Safe
Vertical angular resolution (°)
2
Horizontal angular resolution for 10 Hz (°)
0.2
Horizontal angular resolution for 20 Hz (°)
0.4
Vertical FoV (°)
30
Laser wavelength (nm)
903 (min/max 896/910 nm)
Laser peak FWHM (nm)
-
Full horizontal divergence (mrad) (average of 4 lasers)
3
Full vertical divergence (mrad) (average of 4 lasers)