Spectrosensitometer with wide spectrum, large scale and multistep optical field


With the rapid development of optoelectronic technology, CCD and CMOS cameras have replaced traditional film cameras, but photographic materials still play an irreplaceable role in medical, military, scientific research, aerospace and other fields. Spectral sensitivity is one of the most important characteristic indicators, reflecting the degree of response of the spectrum. Drawing the spectral sensitivity curve needs to detect the reciprocal of the energy received by the photosensitive material under conditions of different wavelengths, different light intensities and different exposure times, and the optical density value produced by development and fixing after exposure. At present, various spectrosensitometer at home and abroad have many shortcomings and defects, such as multiple segmentation exposure, narrow spectral range, few and uneven gray scales, low optical density accuracy, low spectral resolution, inconvenient manual operation and so on. The developed wide-spectrum large-area multi-step light field spectrosensitometer overcomes the above shortcomings, and uses a large-area blazed grating combined with a large-sized cylindrical focusing mirror and a multi-step wedge to form a large-area wide-spectrum two-dimensional exposure field; the horizontal direction is the spectral expansion, and the vertical direction is the step attenuation of the light intensity at different wavelengths. The instrument can automatically measure the light power per unit area on different wavelengths of different light intensity areas on the wedge plate and shutter-controlled exposure time, realize one exposure of the photosensitive material in a wide spectral range, and after developing and fixing, the optical density meter measures its optical density value, according to the national standard (GB10557-89) to draw a spectral sensitivity curve of a certain optical density value of the photosensitive material.

    Professor Huang Yuanshen from University of Shanghai for Science and Technology has been working on the development of high-performance spectroscopic diffraction gratings, the development of grating spectroscopic instruments and the development of high-performance filters. A self-made large-area blazed grating is used as a spectral element, combined with a large-size anastigmatic cylindrical focusing mirror and a 18-step high-precision wedge to form a two-dimensional exposure with a spectral area of 202 mm×90.5 mm and a spectral range of 340 nm to 900 nm. The light field: the horizontal direction is the spectrum unfolding, and the vertical direction is the 18th order of the step wedge; in the development of the multi-step wedge, the nickel-chromium alloy material with the relative wavelength neutrality of 8:2 is proposed. A high-precision 18-step wedge is prepared by using film thickness control technology that controls the coating parameters combined with ion beam bombardment. The optical density values increase from the bottom to the top, respectively, which are 0.00, 0.15, 0.30, ..., 2.55. Each error of the step optical density value is not more than 0.01, each step area is 210 mm×4.5 mm, and the spectral range is 340 nm~900 nm, which compared with the current sales of wedge products at home and abroad, various parameters such as optical density value accuracy, spectral range, size, uniformity and number of steps are among the leading levels. The instrument uses two ball screw pairs to form a two-dimensional displacement platform in the vertical and horizontal directions and a grating ruler to form a closed-loop control. The automatic acquisition system uses LabVIEW to develop the upper computer and the all-in-one PLC to develop the lower computer, which realizes automatic test and is convenient for users. The developed instrument is the leading product with the highest precision, the most complete function and the highest degree of automation among similar instruments at home and abroad.




 

About team
The grating research team of University of Shanghai for Science and Technology started the development of gratings in the 1950s. It is one of the earliest units to start grating research and application in China. For decades, generations of grating developers have worked tirelessly to achieve remarkable results in the development of mechanical gratings, replica gratings, holographic gratings, etc. At the same time, the team has rich practical experience in the development of grating spectroscopy instruments. Many postdoctoral, doctoral and master's degrees have been introduced and trained. Under the leadership of Academician Zhuang Songlin, a strong, composed of old, middle and young, including Professor Zhang Dawei, Professor Huang Yuanshen, senior engineer Ni Zhengji and professional grating production process technician Xu Xiaoping, formed a group of professionals in various related fields. In recent years, the research team has undertaken a number of national and provincial-level projects, and has won many awards. More than 30 related papers have been published, and 15 related invention patents and 9 utility model patents have been applied.

Article

Li Chaoyang, Huang Yuanshen, Sheng Bin, et al. Spectrosensitometer with wide spectrum, large scale and multistep optical field[J]. Opto-Electronic Engineering, 2019, 46(2): 180365.
DOI:10.12086/oee.2019.180365