Instantaneous Testing Method For Transmission Field Using Deflectometry

The application of transmission field testing includes flow field,refractive index field and temperature field,and the detection of transmission optical elements is also one of its applications.At present,various transmission elements are widely used in optical fields such as imaging,and they are also widely used in optical design.At this stage,there are higher requirements for the accuracy and speed of transmission elements testing.Especially in the processing process,the vibration will introduce certain errors to the traditional phase-shifting method of continuous projection and limit its processing accuracy.In this paper,an instantaneous testing method for transmission field using deflectometry has been proposed.Multiple phase shift fringes are combined by frequency carrier method,and a corresponding decoding method is designed to achieve a single transient measurement of a transmission element.The following are the main research contents:The significance of transmission field testing technology is discussed.Based on the research status and development of transmission testing technology at home and abroad,combined with the development of instantaneous testing,the importance of the instantaneous testing method for transmission field using deflectometry is illustrated.Then,the principle of deflectometry is analyzed,providing theoretical support for high-precision transmission field testing.An instantaneous encoding and decoding method based on the frequency carrier method is proposed.Multiple phase-shifted fringes are composited by the frequency carriers in the orthogonal direction,and the phase shift information can be demodulated from the composite pattern based on the filtering principle.We simulate the accuracy of the decoding method and analyze the parameters.The deviation to the ideal phase in the x and y directions is 0.0025 rad and 0.0080 rad,respectively,with good consistency.The nonlinear response of the camera to the screen output is corrected;the crosstalk coefficient matrix is established to adjust and correct the response of each channel in the camera color mode;we analyze the camera imaging model to calibrate the internal and external parameters of the camera and correct the distortion;the deformation of the projection screen is calibrated and the coordinate conversion relationship between the standard balls and the projection screen is established;the wavelength of the exit light from projection screen is calibrated.An experimental system was established according to the instantaneous testing method for transmission field using deflectometry,and is used for the testing of transmission elements.The testing results of the ZYGO interferometer were set as the true values,and the testing results obtained by the method proposed in this paper are compared with that obtained by the traditional four-step phase-shift testing method,the RMS value of the deviation of the measurement result is 0.0107 ?m.