Spectral confocal displacement sensor is a kind of non-contact displacement sensor based on wavelength shift modulation. The principle of spectral confocal measurement transforms the displacement information into the wavelength information, and obtains the measured displacement through the spectrum measurement. Large aperture aspheric surface is the core component of optical system, and its measurement accuracy is directly related to the imaging accuracy of optical camera. The non-contact differential confocal method has the characteristics of non-contact and highprecision. Through the integration of dual frequency interferometer to accurately measure the distance and real-time compensate the measurement distance, the nano level high-precision surface measurement results are obtained, and the measurement accuracy of optical components is improved. In this paper, the non-contact differential confocal method is used to detect the concave aspheric surface with a diameter of 300 mm. Through error file compensation, the surface shape detection accuracy is improved to 12 nm rms, and the scanning detection accuracy is greatly improved to the interference detection accuracy, which meets the imaging requirements of optical system.
|