The Research Of A Measurement Instrument Of Laser Wavelength

Laser interferometry is an important measurement technology. It is widely used in the measurements of dimensions, form and position, surface topography. In these measurements, the output wavelength of the laser is the measurement standard. Both the stability and the accuracy of the laser wavelength have a direct effect on the accuracy of these instruments. The laser wavelength can be easily affected by changes of environment so that the change of the laser wavelength couldn't be avoided. Therefore, it is so necessary to measure and calibrate the real-time output wavelength of the laser that the instrument's measurement accuracy and stability can be ensured. In this paper, a measurement and calibration device for laser wavelength is developed, which is based on the principle of grating diffraction. The main research contents and results are as follows:Firstly, the calculation principle of the laser spot center on QD is analyzed. A principle for wavelength measurement is put up, which combines the grating and two QDs. The system for wavelength measurement is established and the measurement equipment is built up.Secondly, the dedicated electrical circuit of QD is designed for the diffraction signal processing, which consists of a circuit for pre-amplification and a circuit for calculation of the spot center. The pre-amplification circuit is used to convert the current signal into the voltage signal. The calculation of the spot center circuit is used to process the four voltage signal and get the final voltage signal which contains the message of the spot center. The final signal is collected by the PCI bus.Thirdly, the spot model is established by Matlab. Different conditions about QD are simulated and analyzed by Matlab. According to these results, the non-linear errors of the QD are analyzed. Based on all the work, the processing system of the laser wavelength is constructed.Finally, testing experiments are accomplished, which include the stability and repeatability testing experiments. The error analysis is done.