In this paper, a visible-near infrared imaging spectrometer optical system is designed, which is used to detect seawater elements and provides a favorable monitoring means for the protection of marine resources. According to the application background of ocean color detection instruments, the index parameters of the instrument are determined, and a high resolution imaging spectrum system is designed. The front telescope system adopts an off-axis three mirror anastigmat without intermediate real image, with the focal length of 590.75mm and the entrance diameter of 118.15mm;The system comprises an innovative spectrometer design with 0.6 magnification. The de-magnifying optical design allows the telescope to operate at F#/5, while the spectrometers are built in a more compact arrangement at F#/3.The main mirror and three mirrors use Zernike Fringe Sag surface to compensate for the aberration introduced by breaking the classical Offner concentric and isometric structure. The whole optical system comprises a single telescope feeding two functionally identical spectrometers. The spectral range is 0.4-0.9μm, field of view angle is 19 °, spectral resolution is 5nm and instantaneous field of view angle is 0.048mrad, the full field of view and full band MTF is more than 0.8, which is close to the diffraction limit, the RMS radius is less than 4 μm, and the smile and keystone of the spectrometer are less than 10% pixels.
The quality of the optical element surface directly affects the performance of the element, and the inspection and evaluation of the optical element surface is necessary for the manufacturing and processing of optical elements. Optical Coherence Tomography (OCT) is a new type of optical inspection technology, which uses the low coherence characteristics of broadband light sources to obtain the position information in the depth direction of the sample, and has the advantages of non-contact, non-damaging and high resolution. In this paper, a convex lens with a diameter of 25.4 mm was inspected using an 850 nm band fiber optic type spectral domain OCT inspection system. The inspection system mainly consists of a spectral domain OCT inspection system and a scanning device. The inspection data were then fitted to the surface using the least squares method. The PV is 0.97 μm and the root mean square residual is 0.14 μm. This experiment verifies the feasibility of OCT in the field of optical element surface inspection and provides a technical accumulation for the further development of high precision inspection of optical element surface using OCT.
The line laser triangulation instrument is a non-contact dimensional measuring instrument based on the triangulation principle. With the advantages of small size, high accuracy, good stability and wide application scenarios, it is widely used in the industrial production of product surface profile inspection. The measurement uncertainty reflects the stability of the instrument measurement results, it is one of the important indicators of the line laser triangulation instrument, whose theoretical limit is determined by the speckle contrast during the test. By suppressing the speckle on the sample surface, the measurement uncertainty can be effectively reduced. In this paper, we introduce the suppression of scattering during the instrument measurement by temporal averaging method and wavelength diversity method. The paper firstly introduces the speckle theory and the principles of speckle suppression by temporal averaging and wavelength diversity, simulates and analyzes the number of superimposed average images and the speckle suppression effect in the temporal averaging and the power ratio between different wavelength light sources and the speckle suppression effect in the wavelength diversity, respectively. Then, the above methods and effects are experimentally verified by combining with the developed line laser triangulation instrument. Finally, the improved line laser triangulation instrument is compared with the measurement results of the original instrument to calculate the degree of reduction in the measurement uncertainty of the instrument. The experimental results show that the optical method can effectively suppress the sample surface speckle, reduce the measurement uncertainty of the instrument, and lay the technical foundation for the development of a higher precision laser triangulation instrument. It has important application value.
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