CN-121986248-A - Distance measuring device

Abstract

The distance measuring device includes a light source unit that emits a first laser beam and a reference laser beam, a reference interference system that detects a first interference light generated by the first laser beam being interfered and a second interference light generated by the reference laser beam being interfered, and outputs a first signal, a measurement interference system that receives the first reflected light generated by the first laser beam being reflected by the object, and outputs a second signal, and a signal processing system that generates wavelength information on the wavelength of the first laser beam based on the first signal, and calculates a distance from the distance measuring device to the object based on the wavelength information and the second signal, wherein an optical path of the first laser beam and an optical path of the reference laser beam are arranged such that the first laser beam and the reference laser beam do not interfere with each other.

Inventors

• Qingyuan Filial Piety
• NOZAWA KATSUYA
• INADA YASUHISA

Assignees

• 松下知识产权经营株式会社

Dates

Publication Date

20260505

Application Date

20240806

Priority Date

20231026

Claims (17)

1. 1. A distance-measuring device, which comprises a distance-measuring device, The device is provided with: a light source unit which emits a first laser beam and a reference laser beam; A reference interference system for detecting first interference light generated by causing the first laser beam to interfere with the reference laser beam and second interference light generated by causing the reference laser beam to interfere with the reference laser beam, and outputting a first signal; An interference system for measurement, which outputs a second signal by receiving a first reflected light generated by reflecting the first laser light by the object, and A signal processing system configured to generate wavelength information on a wavelength of the first laser beam based on the first signal, calculate a distance from the distance measuring device to the object based on the wavelength information and the second signal, In the reference interference system, an optical path of the first laser light and an optical path of the reference laser light are arranged so that the first laser light and the reference laser light do not interfere with each other.
2. 2. The distance measuring device according to claim 1, The light source section also emits a second laser light having a different wavelength from the first laser light, The measurement interference system is further configured to receive second reflected light generated by the second laser beam being reflected by the object.
3. 3. The distance measuring device according to claim 2, The reference laser has a wavelength shorter than the wavelength of the first laser.
4. 4. The distance measuring device according to claim 2, The interference system for measurement includes: A first optical interference system for interfering the first laser beam with the first reflected light, emitting a third interference light generated by the interference of the first laser beam with the first reflected light, and interfering the second laser beam with the second reflected light, emitting a fourth interference light generated by the interference of the second laser beam with the second reflected light, and And the first light detection system detects the third interference light and the fourth interference light and outputs the second signal.
5. 5. The distance measuring device according to claim 1, The light source part also emits a plurality of second lasers, The wavelengths of the plurality of second lasers are different from each other, The plurality of second lasers each have a wavelength different from the wavelength of the first laser, The measurement interference system is further configured to receive a plurality of second reflected lights generated by the plurality of second laser lights being reflected by the object.
6. 6. The distance measuring device according to claim 1, The laser light source unit is configured to emit a first laser light, and the first laser light is configured to emit a second laser light, and the second laser light is configured to emit a second laser light.
7. 7. The distance measuring device according to claim 1, The reference interferometry system includes: a second optical interference system for causing the first laser beam to interfere and emitting the first interference light generated by the interference of the first laser beam, causing the reference laser beam to interfere and emitting the second interference light generated by the interference of the reference laser beam, and And a second light detection system for detecting the first interference light and the second interference light and outputting the first signal.
8. 8. The distance measuring device according to claim 7, The reference interference system further includes an optical path difference changing means for changing a difference between an optical path length of the first laser beam passing through the second optical interference system and an optical path length of the reference laser beam passing through the second optical interference system.
9. 9. The distance measuring device according to any one of claim 1 to 8, The signal processing system generates the wavelength information representing the peak wavelength by calculating the peak wavelength of the first laser light based on the first signal.
10. 10. The distance measuring device according to claim 2 to 4, The signal processing system calculates a peak wavelength of the first laser light and a peak wavelength of the second laser light based on the first signal, thereby generating the wavelength information indicating the peak wavelength of the first laser light and the peak wavelength of the second laser light.
11. 11. The distance measuring device according to any one of claim 1 to 8, The signal processing system updates the wavelength information when a predetermined condition is satisfied.
12. 12. The distance measuring device according to any one of claim 1 to 8, The signal processing system comprises a memory for storing the generated wavelength information, The frequency of the signal processing system generating the wavelength information is less than the frequency of the signal processing system calculating the distance, The signal processing system calculates the distance based on the wavelength information and the second signal stored in the memory.
13. 13. The distance measuring device according to claim 12, The signal processing system generates the wavelength information and updates the wavelength information stored in the memory when the fluctuation of the wavelength of the first laser light exceeds a threshold value.
14. 14. The distance measuring device according to any one of claim 1 to 8, The light source unit includes an adjustment unit that adjusts the wavelength of the first laser beam based on the wavelength information.
15. 15. The distance measuring device according to any one of claim 1 to 8, The first laser is a laser including a plurality of single modes.
16. 16. The distance measuring device according to any one of claim 1 to 8, The reference interference system and the measurement interference system share an optical interference system.
17. 17. The distance measuring device according to claim 1, The measurement interference system is further configured to receive third reflected light generated by the reference laser beam being reflected by the object.

Description

Distance measuring device Technical Field The present disclosure relates to ranging devices. Background Optical interference using laser light is widely used as a means for acquiring information indicating the distance and/or shape of an object without contact. As an example of this, a Light Detection AND RANGING (LiDAR) of a frequency modulated continuous wave (Frequency modulated continuous WAVE RADAR, FMCW) system is known as a three-dimensional measuring device with millimeter accuracy. Further, optical interference using Optical coherence tomography (Optical coherence tomography, OCT) or Optical comb (Optical comb) is known as a means capable of measuring with micrometer accuracy. They are widely used in the medical and/or industrial fields. In addition, by controlling the optical interference phenomenon with higher accuracy, measurement with nanometer accuracy can be performed. For example, measurement by a michelson interferometer system using a single wavelength laser is one way to measure the difference in distance in nanometer units. While the nano-precision optical measurement represented by homodyne optical interference (Homodyne optical interference) can be performed with high precision without contact, there is a problem in that the measurement range is limited to half the wavelength (submicron unit). Therefore, there are cases where it is difficult to measure a sample having both a structure of a nanometer unit and a structure of several tens of micrometers. As a method for solving the problem, multi-wavelength interference, which is optical interference using two or more single-wavelength lasers, is expected. The multi-wavelength interference can eliminate the cancellation of the conventional measurement range and measurement accuracy, and achieve a longer measurement range and a higher measurement accuracy. For example, in patent documents 1 and 2, by combining the optical interference results of laser lights having different wavelengths, the cancellation of the conventional problems of the length measurement range and the length measurement accuracy can be eliminated, and the long length measurement range and the high length measurement accuracy can be achieved at the same time. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2021-148634 Patent document 2 International publication No. 2008/146480 Patent document 3 Japanese unexamined patent publication No. 5-14867 Disclosure of Invention Problems to be solved by the invention In the distance measurement system using interference of laser light, the wavelength of the laser light fluctuates (fluctuates) in time, and thus the calculated distance information is affected. Specifically, the accuracy of length measurement is reduced, and the stability of the length measurement result is reduced due to measurement over a long period of time. Accordingly, the present disclosure provides a distance measuring device capable of suppressing a decrease in the accuracy of length measurement and long-term stability. Means for solving the problems A distance measuring device according to an aspect of the present disclosure includes a light source unit that emits a first laser beam and a reference laser beam, a reference interference system that detects a first interference light generated by interfering the first laser beam and a second interference light generated by interfering the reference laser beam, outputs a first signal, a measurement interference system that receives a first reflected light generated by reflecting the first laser beam by an object, and outputs a second signal, and a signal processing system that generates wavelength information on a wavelength of the first laser beam based on the first signal, and calculates a distance from the distance measuring device to the object based on the wavelength information and the second signal. In the reference interference system, an optical path of the first laser light and an optical path of the reference laser light are arranged so that the first laser light and the reference laser light do not interfere with each other. Effects of the invention According to the present disclosure, a decrease in the length measurement accuracy and long-term stability can be suppressed. Drawings Fig. 1 is a block diagram showing the structure of a distance measuring device according to the first embodiment. Fig. 2 is a block diagram showing a configuration of a light source unit of the distance measuring device according to the first embodiment. Fig. 3 is a diagram showing a specific configuration of an interference system for measurement of the distance measuring device according to the first embodiment. Fig. 4 is a diagram showing a specific configuration of a reference interference system of the distance measuring device according to the first embodiment. Fig. 5 is a diagram for explaining a principle of a first measurement using a single-wavelength laser by th