Abstract
In case of the off-plane Eagle mounting multislit spectrometer, the perfect performance cannot be expected even with a properly designed holographic concave grating (HCG). Any imaging error of a HCG always leads to a decrease in the S/N of the spectrum. Such effects are discussed in detail and the following results are obtained. 1) A HCG which is designed to eliminate the astigmatism at 5890 Å in the first order can be effectively used over the wavelength range from 7000 Å down to the XUV region. 2) Full image width (FIW) depends on the position of point source, and not on the wavelength. 3) Therefore, any exit slot in the exit multislit mask has its own transmission factor (t-factor). 4) Taking the t-factor into account, the S/N of the spectrum obtained with our multislit spectrometer is found to be about 94% of that attainable with the ideal multislit spectrometer.
