Laser multiple degree-of-freedom measuring system and method

Abstract

A multi-freedom laser measuring system is composed of laser emitter, polarizing-splitting unit, 4-freedom error sensing unit, photoelectric receiver unit and signal processing unit. Said 4-freedom error sensing unit consists of quater-wavelength wave plate, optical splitter and optical reflector. The laser beam is splitted into the perpendicular mutually linear polarized light beams in two polarizing directions. The light beam received by said 4-freedom error sensing unit is splitted to two beans received by two photoelectric receiver. The linearity error of an object in two directions and the pitch angle error can be obtained after signal processing.

Description

(1) Technical field [0001] The invention relates to a laser precision measurement system and method, which is especially suitable for simultaneous measurement of multi-degree-of-freedom errors or motion postures of workpieces or objects when they move along a guide rail. (2) Background technology [0002] The detection of the accuracy of CNC machine tools and machining centers is an indispensable key link in the machine tool industry and machining industry, and is also an important means to ensure the machining accuracy and product quality of machine tools. To sum up, machine tool accuracy detection is mainly used in the following occasions: 1) Measure and draw the geometric accuracy error curve of the machine tool to correct and compensate the geometric error of the machine tool; 2) Conduct a decisive test on the new machine tool to be purchased to determine whether to purchase it ; 3) Periodic inspection of existing machine tools to ensure the machining accuracy of the mac...

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Problems solved by technology

[0004] 1. Traditional geometric optics methods: such as (1) "Optical apparatus for indicating and measuring the roll angular orientation of a movable body" [Optical apparatus for indicating and measuring the roll angular orientation of a movable body, patent number: 3269254, 1966], (2) "Three-axis optical alignment device" [Three-axis optical alignment device, Patent No.: 3375750, 1968], (3) "Three-axis angle sensor" [Three-axis angle sensor, Patent No.: 4560272, 1985], etc. are the 20 In the 1960s and 1980s, there were researches and patents in this field. These patented technologies used traditional optical methods, using ordinary light sources as illumination, and had defects such as complex optical systems, low measurement accuracy, and few measurement parameters.

[0005] 2. Using the diffraction phenomenon of light: such as (1) "Multi-axis optical alignment system including a spatial filter" [Multi-axis optical alignment system including a spatial filter, patent number: 3701602, 1972], (2) "Three Three and five axis laser tracing system” [Three and five axis laser tracing system, Patent No.: 4714339, 1987], (3) “Multi-axis alignment apparatus” [Multi-axis alignment apparatus, Patent No.: 4804270, 1989], etc. The simultaneous measurement of three-dimensional angles is realized by using the diffraction phenomenon of light or the holographic grating. The disadvantages are that the measurement accuracy is not high, the measurement parameters are few, the optical system is complex, and the measurement head is equipped with a follower cable, which makes on-site measurement inconvenient.

[0006] 3. Methods based on laser tracking measurement: such as (1) "Laser tracking measurement system and measurement method for target spatial position and attitude" [China Patent Application No. 99109623.1], etc. This type of measurement method has a large measurement range and high measurement speed. However, there are defects such as low measurement accuracy, complex measurement system, and expensive measurement equipment.

In addition, almost all of these systems require cables to connect the moving measuring head to the rest of the measuring instrument, making quick and easy measurements difficult

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