Dear all,

I am trying to replicate the optical design of a Schwarzschild imaging spectrometer of the paper 
Xue, Qingsheng. "Modified Schwarzschild imaging spectrometer with a low F-number and a long slit." Applied Optics 52.28 (2013): 6956-6961, also included in attachment.

More specifically, I am interested in the design using only concentric spherical mirrors. I used the values from their Table 1 and first column of Table 2 (they seem consistent with their formulas), giving the Zemax design also included in attachment.

However, I do not get even close to the performance they show in Figure 7b, where my spot sizes are about 10x larger, even with a higher f/#. And even allowing a small deviation to the initial values and re-optimizing did not significantly improve the results.

Does anyone have experience with this particular design or see any obvious mistakes?

Thanks for your help,

Best regards,

Indy Magnus