The large diameter and long focal length collimator can be used to measure the parallelism between the various optical axes of multi-axis photoelectric system. After moving, vibration or change of ambient temperature, the collimator components location will change, and its own parallelism will disorder. Outside the laboratory, it's difficult to recalibrate the disorder collimator. This will directly affect the reliability of the collimator measurement results. In this paper, a self-calibration method was proposed, the collimator structure was optimized, CCD detection imaging was introduced and self-calibration component was designed. The radial calibration and depth of focus calibration principles were studied in collimator. Based on this, a set of collimator will be developed, which can measure the optical axis parallelism and its own parallelism included. When the collimator own parallelism disorders in the use of an external field, it's easier to finish the self-calibration in the scene. The measurement accuracy of the instrument can be ensured. A set of sun fleck positioning system software will be programmed, and it can be used to coordinate with self-calibration and measuring the optical axis parallelism function in the collimator. The study in this paper has important practical significance for scientific research and engineering experiments.
KEYWORDS: Silicon, Nanostructures, Absorption, Reflectivity, Solar cells, Silicon films, Thin film solar cells, Silicon solar cells, Diffraction gratings, Nanolithography
Enhancing the light absorption in ultrathin-film silicon solar cells is important for improving efficiency and reducing cost. In this paper, we report a highly effecient cosine periodic nanostructure as light trapping texture. The design and fabrication as well as measurement of cosine nanotextures were presented. The optimized structure yields an average reflectance of 7.07% at an equivalent silicon thickness of 10μm, much better than planar and random pyramid structures. The measurements demonstrate that the absorptions in ultrathin film solar cells are very close to the Yablonovitch limit for the entire solar spectrum and insensitive to the angle of the light. This approach is applicable to various thicknesses and promising in future glass-based thin film solar cells.
When solar radiation transmits in the atmosphere, radiation wave band from 240nm to 280nm is strongly absorbed by the
ozone layer, which makes the ultraviolet radiation in this wave band difficult to reach the near earth surface. It forms the
solar radiation blind region on the near earth surface that is usually called solar blind region. Because of the strong
absorption, the solar blind ultraviolet detecting system works in wee background noise condition. In this paper, we
design a set of ultraviolet detecting experiment system. From the radiometry, we establish an improved estimate of the
operating range model based on the target signal, background signal difference and noise of detector. Using the improved model, we can calculate the operating range for point target in solar blind ultraviolet detecting system. For the special ultraviolet target, the calculated values are consistent with the practically measured values in the experiment system designed in the paper.
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