During the production of a lens system, the assembling and manufacturing tolerances must be accurately controlled to ensure production efficiency. Thus, it is important to analyze and optimize the tolerance sensitivity of the lens system during the optical design phase to reduce optical performance degradation. We proposed an approach for appropriately controlling the tolerance sensitivity of a lens system. The proposed sensitivity optimization method can homogenize image performance for the same field under different tolerance values. Based on the results, we show that the implementation of the proposed method sharply reduces sensitivity and, consequently, improves the product yield rate by 15 to 17% compared with a traditional optimization method. As a practical example, a 40-megapixel f1.8 mobile phone camera lens design and optimization process was performed in our study. Our preliminary experimental results confirm that the proposed method is effective to reduce the optical sensitivity of the camera lens.
The Multi-channel Photometric Survey Telescope (Mephisto) have a 1.6m primary mirror with 1.3 focal ratio, a 2degree field of view. Mephisto is capable of imaging the northern sky in three colors simultaneously. Its 0.7m secondary mirror is quite sensitive for alignment. The field dependent image quality of the misaligned Mephisto optics would be characterized as asymmetric, continuously varying and nonlinear with the misalignments. When the real-time field-PSF is measured from the astronomical images, the residual field-PSF of nominal optical design is defined as the goal of the merit function, the misaligned values of Mephisto secondary mirror can be calculated, by using the PSO (Particle swarm optimization) algorithm. The truth is field-PSF can be numerically expressed with ellipticity of the imaging stars or distribution of the ellipticity. However, for resolving the misalignment values, the stable field-PSF modes are needed, instead of random modes. PCA (Principal component analysis) algorithm is used for eliminating the random perturbations, such as turbulence.
The Antarctic survey telescope (AST 3-3) near infrared(NIR) camera is designed to conduct the Kunlun Infrared Sky Survey which will provide a comprehensive exploration of the time varying Universe in the near infrared. It is going to be located at Dome A, on the Antarctic plateau, one of the most unique low background sites at the Kdark band (2.4μm). Carefully designed thermal emission from the telescope and the Kdark camera is very important to realize background limited operation. We setup a scattering and thermal emission model of the whole system to optimize the camera performance. An exposure time calculator was also built to predict system performance.
AST3-NIR is a new infrared camera for deployment with the AST3-3 wide-field survey telescope to Dome A on the Antarctic plateau. This project is designed to take advantage of the low Antarctic infrared sky thermal background (particularly within the Kdark near infrared atmospheric window at 2.4 μm) and the long Antarctic nights to provide high sensitivity temporal data from astronomical sources. The data collected from the Kunlun Infrared Sky Survey (KISS) will be used to conduct a range of astronomical science cases including the study of supernovae, exo-planets, variable stars, and the cosmic infrared background.
Modern telescopes typically have prime focus speeds too fast for direct use with standard numerical aperture (NA=0.22±0.02) silica-cored fibers. Specifically, the current design for the proposed Maunakea Spectroscopic Explorer (MSE) telescope is ~f/2, requiring fibers with NA>0.25. Micro foreoptics can be used to slow the beam, as used on the prime focus spectrograph (PFS) on Subaru, but this adds cost and complexity, and increases losses. An attractive alternative is offered by high NA pure silica-cored fibers, which can be used directly at f/2, and which are now available from multiple vendors. We present throughput and focal ratio degradation measurements on two samples of these high NA fibers. It is found that the measured attenuation losses are comparable with the best available standard NA fibers. The fibers were also tested for focal ratio degradation, and the fiber from CeramOptec was found to have acceptable FRD, representng additional collimator losses ~1%. The near field performance of the high NA fiber is also investigated and these high NA fibers exhibit very good scrambling performance; we saw no evidence for significant output near-field variations for varying input beam angles or position in a 50m fiber.
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