Haili Yu

Sequentially timed all-optical mapping photography is one of the main emerging ultra-fast detection technologies that can be widely applicable to ultra-fast detection at the picosecond level in fields such as materials and life sciences. We propose a new optical structure for an all-optical spatial mapping module that can control the optical field of two-dimensional imaging while improving spectral resolution and detector sensor utilization. The model of optical parameters based on geometrical optics theory for the given structure has been established, and the theoretical analysis of the inter-frame energy crosstalk caused by incident beam spot width, chromatic aberration, and main errors of the periscope array has been conducted. The optical design of the two-dimensional (2D) all-optical spatial mapping module was finally completed using ZEMAX OpticStudio 2018 software. The results show that our optical module can realize targets of 16 frames and 1.25 nm spectral resolution.

An interference method to remove all mosaic grating errors using a phase-difference reference window without compensation for coupled mosaic errors or analyzing the far-field diffraction intensity patterns is proposed. The reference window is achieved by adding a small-aperture prism; therefore, the incident light on the mosaic gratings contains two different angles of incidence and optical paths, eliminating the uncertainty of longitudinal mosaic error in the interferometer. The mathematical model of the method is established and optical arrangement is presented. Interference fringes with the reference window and alignment process are simulated and the accuracy of mosaic errors are analyzed. The experimental and simulation results show that our method can eliminate longitudinal mosaic error and all other mosaic grating errors. The accuracy of angle mosaic errors can be less than 1 μrad and position mosaic errors can be to the nanometer level. Compared with the far-field diffraction intensity patterns method, our method reduces the complexity of the optical structure and ensures measurement accuracy.

It is hard and costly to test resolution directly, because the focal length of testing equipment could be nearly ten meters. Solving resolution by diffraction wavefront aberration indirectly is an effective solution to this problem. A normalization model of solving resolution using fitting coefficients of Zernike polynomials was established based on the spectral imaging theory of Fourier optics. The relationship between resolution and wavefront aberration of diffraction gratings was illustrated by this model. Finally, a new method of testing resolution using fitting coefficients of Zernike polynomials was proposed. According to this method, the resolution of a grating is tested by ZYGO interferometer indirectly. Compared with direct method, results indicate that the error of indirect method is less than 4.22%, and this method could be an effective way to avoid the difficulty of direct method to solve resolution. Meanwhile, this method can be used in ZYGO interferometer to solve resolution by wavefront testing easily.

A new-style system that automatically measures the diffraction efficiency of plane reflection grating was designed. The continuous illuminant was adopted for illumination, the duplex grating spectrograph structure was applied, and the linear array NMOS was the receiving component. Wielding relevant principle of the grating spectrograph, theoretical analysis principle was carried out for the testing system. Integrating the aberration theory of geometrical optics, the image quality of this optics system was analyzed. Analysis indicated that the systematic device structure is compact, and electronics system is simplified. The system does not have the problem about wavelength sweep synchronization of the two grating spectrographs, and its wavelength repeatability is very good. So the precision is easy to guarantee. Compared with the former automated scheme, the production cost is reduced, moreover it is easy to operate, and the working efficiency is enhanced. The study showed that this automatic measurement instrument system features a spectral range of 190-1 100 nm and resolution is less than 3 nm, which entirely satisfies the design request. It is an economical and feasible plan.