Auxiliary device for large surface shape measurement based on laser tracker and measurement method

Abstract

The invention provides an auxiliary device for large surface shape measurement based on a laser tracker and a measurement method, which can realize fast and efficient detection in the large surface shape measurement of the laser tracker. The auxiliary device mainly comprises a four-wheel-drive trolley and a parallelogram elevating mechanism arranged at the front end of the trolley, wherein one side of the elevating mechanism is arranged on a disc, the disc is arranged on the trolley by four bolts, a reflection target (target mirror described in the following descriptions) of the laser tracker is arranged on the elevating mechanism, the target mirror raises when the trolley moves and is not in contact with a tested surface, and the target mirror descends when in measurement and is in full contact with the tested surface. The space angles of the target mirror and a tracking head are measured in real time, then the target mirror is automatically aligned with the tracking head through changing the gesture of the target mirror, and therefore, the phenomenon of light breaking is not caused, and the measurement efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of laser measurement, in particular to an auxiliary device and a measurement method for large-scale surface shape measurement based on a laser tracker. Background technique [0002] The laser tracker is a new type of large-scale and high-precision three-dimensional space coordinate detection equipment. For example, the T3 tracker of API Company has a range of up to 60 meters and an accuracy of micron level. It has been increasingly used in the field of large-scale surface shape measurement. Many applications. The laser tracker is mainly composed of a tracking head, a measuring target (hereinafter referred to as the target mirror) and a control box. The working principle of the laser tracker is to place a measurement target on the target point, that is, the target mirror, and the laser beam emitted from the tracking head hits the target mirror, and the target mirror reflects the laser beam back to the tracki...

AI Technical Summary

Problems solved by technology

The current laser ranging system mainly includes two methods: interferometric distance measurement and absolute distance measurement. Laser interferometric distance measurement uses the phase method to measure distance. It has high precision, but after the laser beam path is interrupted, the interferometer must be reset. The initial distance, that is, the target mirror returns to the initial position to re-measure, and the measurement efficiency is low

Absolute measurement is to calculate the distance by using the time difference of the round-trip laser path. After the beam is blocked, as long as the target mirror is found again, the measurement can be continued. The measurement efficiency is high, but the measurement accuracy is not high.

During the measurement process, when the target mirror moves, the tracking head can automatically adjust the direction of the beam to align with the target mirror, but at the same time, it is required that the angle between the laser beam and the incident surface of the target mirror cannot exceed a certain angle (the most commonly used target for laser tracking The mirror is a spherical reflector SMR, which requires that the incident angle of the beam on the end surface of the target mirror should not deviate from the vertical direction by more than ±20°), if it exceeds this angle, the target mirror cannot return the laser beam, that is, the phenomenon of light failure

[0003] At present, the main manufacturers of laser trackers in the world are Leica, API, and Faro. The laser trackers produced by them all need the target mirror to touch the surface to be measured. Although these companies provide some auxiliary accessories such as standard rods, bases, etc. , but manual operation is still required in the specific measurement

For some large-scale surface shapes, such as large-aperture astronomical optical telescope mirrors, the surface shape measurement accuracy will reach sub-micron level, and laser tracker interferometric measurement must be used, but interferometric measurement is inefficient, labor-intensive, and easy to break light

Although the API company has developed a new type of intelligent probe, which can automatically receive light and improve the measurement efficiency, this technology still uses the absolute measurement principle in essence, and the measurement accuracy is low.

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