There are lot, depending on your requirements. Anyway you can try: S-,kI }~GV'7d1 1, Refractive: an achromatic as positive + plano-convex as negative; Jk~UEqr+ OR g^n;IE$B 2, Reflective: two parabolic mirrors; P%jkKE?B4 ;qG1r@o Both of them affer nice spherical aberration performance. 8>v7v&Bh| 0~.)GG%R>D Reminder: compute the laser beam density, ensure you have enough strong optical coating. uXP-
J]> -&7=uRQk Good luck.
Hi, :Z]/Q/$ A>[hC{ The following is a link of technical data of optical adhesives, hope it be helpful: a?l_-Fi US"2O!u http://www.lienhe.com.cn/uvadh/NOA60.htm !+%Az*ik +i2YX7Of Double check from your lens vendor waht type of adhesive they use for your cemented doublet. 4h(jw v5P*<U Ax It is OK to use the spaced doublet design as a backup, if so, please pay a lot attention on the opto-mechanical design and assembling. 6{lG1\o z`;&bg\8 Again, good luck.