Effect of refractive index measurement error on immersion grating spectral lines

Abstract

Firstly, the effect of refractive index changes on spectral line spacing is calculated and analyzed. Because refractive index changes with wavelength-variety, theoretically, the 0.5 nm interval should be separated by 5 pixels. The spectral distribution will drift with considering the changes in refractive index. At the same time, the inversed spectral line drift caused by measurement errors(&plusmn;1&times;10-3?1/4?&plusmn;1&times;10-4?1/4?&plusmn;1&times;10-5) are analyzed. The same refractive index error, the effect on long waves is greater than short waves. When the refractive index is positive, the spectral line drifts in the negative direction. When the refractive index is negative, the spectral lines drift in the positive direction, and the positive and negative drift are basically symmetrical. When the accuracy error of refractive index measurement is &plusmn;1&times;10-4, the spectral line drift is 0.7 pixels. When the error increases or decreases by an order of magnitude, the number of drift elements also increases or decreases by the same order of magnitude. &copy; 2019 SPIE.</p