Parameters of XUV spectrometer with 155 mm incident distance

In order to make the grazing incidence XUV flat-field spectrograph’s size shorter for the convenience of use, a ray-tracing code is set to research the influence of the concave grating’s parameter on the spectrum imaging when the incident distance is 155 mm and the focusing surface is still flat. It is found that for the concave grating with curvature radius of 5 649 mm and 1/1 200 nm nominal spacing of the grooves, the angle of incidence is 87.5°, when the incident distance is 155 mm, the focus parameter is -21/R and the coma-type aberration parameter is 4.655102/R2, a better imaging effect within the wave band of 12 ~ 40 nm is realized.