New Scheme of MEMS-Based LiDAR by Synchronized Dual-Laser Beams for Detection Range Enhancement
<p>Block diagram of the MEMS-based LiDAR system with synchronized laser beams.</p> "> Figure 2
<p>A simple verification architecture of an optical path for the synchronized dual-laser beams. The path of the dashed line is the detection optical path from the main laser source, MEMS mirror, and receiver optics to APD. The path of the dash-dotted line is the enhanced signal optical path from the auxiliary laser source directly reaching the APD.</p> "> Figure 3
<p>The schematic of auxiliary light amplifies the reflected signal optically. The solid line represents the signal value, and the dotted line represents the threshold value.</p> "> Figure 4
<p>The time sequence of electrical trigger signal, primary and auxiliary lasers, and environmental noise obtained by an oscilloscope. To exceed the threshold, the power coupling of the main light and the auxiliary light must rely on an attenuator to adjust the power of the auxiliary light (A and B).</p> "> Figure 5
<p>The oscilloscope signal is directly from an APD on detecting reflected light in two types of LiDAR architecture: (<b>a</b>) without an auxiliary laser light and (<b>b</b>) with auxiliary laser illumination. The red solid line displays the value of the light signal, and the dotted line displays the value of the threshold.</p> "> Figure 6
<p>The point-cloud image from APD catches the received optical signal from the target (<b>a</b>) without an auxiliary laser light and (<b>b</b>) with auxiliary laser illumination. As seen by the image, under the identical detection effect, there are far more point clouds with the auxiliary light system turned on than without. Additionally, the edge features of the target object as a whole are made evident.</p> "> Figure 7
<p>The architecture of the hardware configuration for the MEMS-based LiDAR. Under the casing, the entire LiDAR structure covers the laser light source group, optical lens group, computer circuit board, electronic control circuit board, and power control circuit board. We set up every component grid using space optimization and visual route design.</p> "> Figure 8
<p>The method and analysis describe the FOV and angular resolution in MEMS-based LiDAR. Conduct the angular resolution test in the situation shown in (<b>a</b>). Configure the environment in compliance with the requirements of the standard test. Use trigonometric functions and point-cloud data to compute the angular resolution; (<b>b</b>) although the transmitted object’s actual size is equal to the proportionate relationship of the site size, users can utilize this information to estimate the approximate number of point clouds.</p> "> Figure 9
<p>The method and analysis description for the FOV and angular resolution in MEMS-based LiDAR: (<b>a</b>) is the optical image of the test environment; (<b>b</b>) is the point-cloud image without the auxiliary laser light; and (<b>c</b>) is the point-cloud image with the auxiliary laser light. The picture (<b>c</b>) shows more point clouds, project contours, and weak signals from objects farther behind.</p> "> Figure 10
<p>The maximum detection range is a function of the incident main laser power. The LiDAR presents the detection range by the line of dots when activating the auxiliary light system. The auxiliary light power is 35.5% of the leading laser power, and the squares line represents when the auxiliary light system is off. The detecting distance will be 16% farther when the auxiliary light system is active than when it is inactive.</p> ">
Abstract
:1. Introduction
2. Structure of MEMS-Based LiDAR
2.1. Scheme of MEMS-Based LiDAR
2.2. Theory of Dual-Laser Sources to Enhance the Detection Distance
3. Measurements and Results
3.1. Measurement of the Verification Architecture for the Synchronized Dual-Laser Beams
3.2. Measurement of MEMS-Based LiDAR
3.3. Measurement of FOV, Angular Resolution, and Maximum Detected Distance
3.4. Results and Discussions
3.5. Simulation Results
- Price: A high-power laser chip with a wavelength of 1550 nm and a power of more than 4 W is not a product that one can commercially purchase. This product costs more than the standard model.
- Power Consumption: With or without an additional laser, the LiDAR’s overall output power was smaller. In general, the main laser’s consumption rate was smaller. However, when directly pumping the auxiliary laser system into the APD when the range is very close, there is very little loss of advantage.
- Dimension: The high-power laser module was more extensive compared to the low-power one. Therefore, this will impact the module structure and other electrical component parameters. This specification indicates that the volume will be larger than low-power LiDAR. Additionally, as the auxiliary laser system is an additional laser light source attached to the existing structure, with an input direction of light from the outside to the inside, it requires extra room. In general, there will be little difference between the two volumes.
4. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Item | Model | Advantage | Shortcoming |
---|---|---|---|
1 [11] | The dual-light source effect causes a stochastic resonance system. | A single light source splits into two and adjusts itself to enhance the intensity of the light signal. | A larger volume reduces the detection distance. |
2 [12] | A circuit module boosts the signal that is received. | Able to boost weak signals to the sensor’s lowest possible reception level. | Synchronous control will result in a momentary black space. |
3 [13] | Increase the power of vertical-cavity surface-emitting laser (VCSEL). | Using light source array mode to boost optical power. | The cost is too high; light source module temperature is too high. |
4 [14] | Using high-sensitivity avalanche photodiode (APD). | Developing low excess noise APDs with new material (GeSi). | In development. |
5 [15] | Improve the optical lens modules’ matching. | Less of an effect on the LiDAR’s general structure. | Extremely exacting in terms of lens design and specs. |
Measurement Data | Specification of MEMS | |||
---|---|---|---|---|
Measurement distance (cm) | 280 | 380 | 480 | 380 |
Length for field (cm) | 240 | 320 | 400 | NA |
Width for field (cm) | 132 | 163 | 218 | NA |
Horizon for FOV (°) | 46.2 | 45.6 | 45.2 | 45 |
Vertical for FOV (°) | 26.5 | 24.2 | 24.4 | 25 |
Resolution for object | 36 × 76 | 27 × 61 | 22 × 47 | NA |
Resolution | 392 × 218 | 393 × 216 | 400 × 223 | NA |
Angular resolution (H °) × (V °) | 0.1 × 0.1 | 0.1 × 0.1 | 0.1 × 0.1 | NA |
The Output Power of the Auxiliary (mW) | Maximum Detection Range (m) | Enhancement Rate (%) |
---|---|---|
0 | 107 | X |
0.1 | 113 | 6.7 |
53.6 | 115 | 8.5 |
204 | 116 | 9.5 |
355 | 124 | 16 |
Price | Power Consumption | Dimension | |
---|---|---|---|
Without Auxiliary Laser | High | High | Smaller |
With Auxiliary Laser | Low | Low |
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Huang, C.-W.; Liu, C.-N.; Mao, S.-C.; Tsai, W.-S.; Pei, Z.; Tu, C.W.; Cheng, W.-H. New Scheme of MEMS-Based LiDAR by Synchronized Dual-Laser Beams for Detection Range Enhancement. Sensors 2024, 24, 1897. https://doi.org/10.3390/s24061897
Huang C-W, Liu C-N, Mao S-C, Tsai W-S, Pei Z, Tu CW, Cheng W-H. New Scheme of MEMS-Based LiDAR by Synchronized Dual-Laser Beams for Detection Range Enhancement. Sensors. 2024; 24(6):1897. https://doi.org/10.3390/s24061897
Chicago/Turabian StyleHuang, Chien-Wei, Chun-Nien Liu, Sheng-Chuan Mao, Wan-Shao Tsai, Zingway Pei, Charles W. Tu, and Wood-Hi Cheng. 2024. "New Scheme of MEMS-Based LiDAR by Synchronized Dual-Laser Beams for Detection Range Enhancement" Sensors 24, no. 6: 1897. https://doi.org/10.3390/s24061897