Absolute distance measuring device based on intensity modulation

Abstract

The invention provides an absolute distance measuring device based on intensity modulation. The device comprises a laser, a laser driving part, a laser temperature control part, a signal source part,an MZ electro-optical modulator, an MZ modulator bias part, an optical fiber interconnection system, a light beam expander group part, a corner reflector, a photoelectric receiving and signal conditioning part and a control and digital signal processing part, wherein the output end of the laser driving part is connected with the laser, the laser temperature control part is connected with the laserto form an automatic constant temperature control system, the output end of the MZ modulator bias part is connected with the MZ electro-optical modulator, the output end of the laser is connected with the optical fiber interconnection system, and the laser outputs an optical signal with constant power to enter the optical fiber interconnection system. The beneficial effects of the invention are that the device improves the distance measurement precision, is low in cost, is small in size, is better in system reliability and stability, and is lower in requirements for an optical assembly technology.

Description

technical field [0001] The invention relates to optical measurement, in particular to an absolute distance measurement device based on intensity modulation. Background technique [0002] Laser tracker is an important key instrument and equipment in large-scale equipment manufacturing, which can track space moving targets and measure the high-precision space three-dimensional coordinates of targets in real time. Its host mainly includes distance measurement module, angle measurement module, tracking control module, reflector, tripod, data processing terminal and so on. The core distance measurement module is composed of two parts: interferometric ranging module (IFM) and absolute ranging module (ADM). The ADM can measure the absolute distance, and can realize the function of continuous connection after light interruption. A stable and reliable high-precision absolute distance ranging is very critical for laser trackers. [0003] In the "Method and Measuring Device for Meas...

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Problems solved by technology

[0005] (1) The pulse time-of-flight laser ranging method measures the flight time of the laser pulse between the distance measuring device and the target to measure Δt and then multiplies the distance by the speed of light. The measurement accuracy of the existing technology for the flight time is generally tens of picoseconds The accuracy is generally at the centimeter level, which is difficult to meet the requirements of the absolute ranging of the laser tracker on the order of ten microns;

[0006] (2) The photometry and range measurement of the phase method measure the phase difference between the target return light and the emitted beam. The accuracy is limited by the phase detection accuracy. Micron level requirements;

[0007] (3) The femtosecond laser ranging system is expensive and bulky, making it difficult to integrate into a laser tracker;

[0008] (4) The frequency modulation continuous wave ranging and multi-wavelength interference ranging systems have complex structures, high costs, poor system reliability and stability, and difficult to maintain ranging accuracy;

[0009] (5) The method of using electro-optic crystal polarization modulation to replace the Fizeau gear to measure the light velocity proposed by the Swiss company Leica uses a spatial optical path, which is susceptible to interference from beam jitter caused by additional polarization and drastic changes in the environment, and has extremely high requirements on the optical assembly process, resulting in System stability is low

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