The Reserach On The Optical System Design And The Measurement Error Correction On The Automatic Test Instrument For Grating Diffraction Efifciency

This paper was mainly focused on the design and simulation of optical system ofthe automatic test instrument for the grating diffraction efficiency, and the method ofmeasurement error correction was also investigated. The main research on theautomatic test instrument for the plane grating diffraction efficiency are as follows:firstly, the design method of the double monochromator of the plane grating wasproposed, on the basis of lossless luminous flux, the light source, detector and thestructure of the optical path was selected, and the spot diagram of the image surfaceand the results of real ray trace were given. Secondly, the sinusoid that accords withthe grating equation was proposed to be served as the function of the wavelengthcalibration of the instrument. Based on the principle of the least square method, theformula of the fitting residual error of the wavelength calibration was given. Usingthe Nelder-Mead simplex method, the undetermined coefficient of the fitting residualerror was solved, which founded the precise formula between the wavelength and thegrating turning angle. The accuracy of the method was verified through theexperiment, based on which the research of wavelength was calibrated. Thirdly,through analyzing the main factors, the spectral broadening of exit beam and section-changed of diffraction beam that influence the testing results duringmeasurement, the relationship between them and wavelength and groove density wasgiven. Based on a large number of experiment data, the correction model wasestablished using the multiple linear regression analysis. Additionally, the correctionmodel was compiled as the testing programming, which can correct the testingresults automatically when the test was finished. The results deviation after modifiedwas less than±2%, which enhanced the measurement precision for one order ofmagnitude.On the basis of the research on the automatic test instrument for the planegrating diffraction efficiency, a series of similar work was developed according to theautomatic test instrument for the concave grating diffraction efficiency. fourthly, theoptical system of the type III and the type Ⅳ concave gratingwas designed andsimulated respectively, the detector parameters and the structure of the optical paththat suitable for multi-type concave grating were selected. Fifthly, the testing methodof the diffraction efficiency of the type III concave grating was proposed and verified.Using the same measurement error correction method with the automatic testinstrument for the plane grating diffraction efficiency, the precise testing of theconcave grating diffraction efficiency was achieved.Finally, the measurement performance of the automatic test instrument for theplane and concave grating diffraction efficiency respectively was analyzed. Thetesting data showed that, the testing accuracy of the two instruments, the testingstability and the testing speed were±2%,0.29%and15pieces/hour respectively. Andthe testing repeatability were less than2%. The above performance index satisfies theexpected requirement.