Beijing Jiaotong University

Qibo Feng

Zhan Gao

Bin Zhang

Xu Wang

Shanwei Yang

Chenjia Gao

Cunxing Cui

Jie Qin

Shengjia Wang

Jing Yang

Jiakun Li

Fajia Zheng

A method for full-field measurement using Doppler imaging, comprising the following steps: turning on a laser and adjusting the laser; adjusting a spatial filter to obtain circular laser spots having uniform intensity distribution; adjusting a quarter-wave plate and a whole polarizer in a system, and requiring two beams in a reference object and a measured object having different frequencies and perpendicular polarization directions; applying slight pressure to the measured object, setting a charge coupled device (CCD) camera into a continuous acquisition mode, observing interference fringes, and adjusting a light path so that the fringes are clear and visible; setting the sampling frequency, sampling time, captured image format and resolution size of the CCD camera; turning on a lithium niobate crystal drive power switch to produce a heterodyne carrier frequency; applying continuous equal pushing force to the measured object by means of piezoelectric ceramics (PZT) so as to make the measured object produce continuous bending deformation; controlling the CCD camera to sample using a computer, and collecting a set of time series light interference images along with the continuous deformation of the measured object; and processing the time series light intensity interference image to obtain a three-dimensional data module comprising continuous deformation of the measured objects distributed in time and space.

Method for full-field measurement using dynamic laser doppler imaging

The present invention discloses a laser measurement system and method for measuring a six-degree-of-freedom geometric error of a rotating shaft. The system comprises a laser emission unit, a six-degree-of-freedom error measurement unit, a six-degree-of-freedom error sensing unit and a servo tracking unit capable of being installed on a rotating shaft to be measured, in which the six-degree-of-freedom error measurement unit enables light to be emergent the six-degree-of-freedom error sensing unit and generates a measuring signal according to emergent light and reflected light and backward reflected light of the six-degree-of-freedom error sensing unit, and the servo tracking unit comprises a four-dimensional adjustment mechanism for realizing four- dimensional adjustment; a motor fixedly installed on the four-dimensional adjustment mechanism; an angle measurement sensor for measuring a rotation angle of the motor; an installation plane fixed on the four-dimensional adjustment mechanism, coaxially rotating with the motor and used for installing the six-degree-of-freedom error sensing unit; and a control circuit for controlling the servo tracking unit according to the measurement signal from the six-degree-of-freedom error measurement unit. The present invention can realize simultaneous and rapid measurement of the six-degree-of-freedom geometric error of the rotating shaft.

Laser measurement system and method for measuring six-degree-of-freedom geometric error of rotating shaft

A laser measurement system for measuring up to 21 geometric errors, in which a six-degree-of-freedom geometric error simultaneous measurement unit and a beam-turning unit are mounted on either the clamping workpiece or the clamping tool, while an error-sensitive unit is mounted on the remaining one, the beam-turning unit has several switchable working postures and multi-component combinations in its installation state, it can split or turn the laser beam from the six-degree-of-freedom geometric error simultaneous measurement unit to the X, Y, and Z directions in a proper order, or the beam-turning unit can split or turn a beam from the error-sensitive unit to the six-degree-of-freedom geometric error simultaneous measurement unit. The present invention is of simple configuration and convenient operation. Up to 21 geometric errors of three mutual perpendicular linear motion guides are obtained by a single installation and step-by-step measurement.

Laser measurement system and method for measuring 21 GMEs

A six degree of freedom laser simultaneous measurement system, wherein a laser emitting unit is separated from a fixed sensor head; the laser emitting unit is connected with the fixed sensor head by a single polarization maintaining fiber; a moving unit comprising the reflector and the beam splitter is mounted on the linear guide; utilizing of the single polarization maintaining fiber, which connects the laser emitting unit with the fixed sensor head, reduces the influence of heat generated by laser source on the measurement accuracy, and makes the system more compact and integrated. The six degree of freedom errors, including position error, horizontal and vertical straightness errors, pitch, raw and roll, can be measured simultaneously by only one incident light. The non-cable connection on the moving unit makes long-distance and in-situ measurement possible.

6DOF error laser simultaneous measurement system with a single polarization maintaining fiber coupling and transmitting the dual-frequency laser

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Beijing, China

Qibo Feng