Optical Design Of Portable Of Spectrophotometer For Color Measuring

As the development of the industry, the color measuring is used widely. In many industries, it's one of many reference indicators in quality assessment of products. However, the spectrophotometers for color measuring that we always used have large volume, high cost, and need to be connected with the computer, the characteristics don't satisfy the requirements those need to measure the color of sample everywhere and real-timely. So it is very important to study the methods to obtain a color measurement instrument that has many characteristics, such as high accuracy, low cost, small volume, etc.In this paper, it included several parts as follows:Firstly, the optical system structure had been decided. Based on the working principle of spectrophotometer and the theory of optical design, and with portable instrument, low cost, a fit spectral range and resolution requirements as specify targets, the crossed Czerny-Turner structure based on plane diffraction gratings was proposed to be the system structure after comparison and analysis of some feasible ways. Optical software was used for simulating and optimizing and analyzing of the the optical system. The results showed that these parameters satisfied the designing requirements entirely, especially in portability and low cost.Secondly, tolerance analysis was done. After calculating the errors of the radius, the tilt and decenter of surfaces and elements, the distance of air and glass, the elements surface, we got the result of tolerance analysis. According to the result, the tolerance satisfied the requirement.Thirdly, stray light analysis was done. After inputting data of the design results in TracePro optical software and setting up parameters of every element surface characteristics and light properties, the stray light analysis was done. The analysis result showed that the stray light coefficient is less than 0.2%, the stray light in the optical system has little effect on the measurement results of the color measuring.Finally, through analyzing the parameters of the silicon photodiode array, such as the spectral responsivity, noise equivalent power, the Linearity, response time, etc, we estimated the source power that was needed.