Hi John,

You can use a thin mask very close to the detector. One mask surface (front, back) should have specified coating as required (In the attached screenshot front face of the 2nd surface has I.90 (90% T and 10% R) coating). 

While defining the new coating, the angle of incidence should also be taken care.

 

Hope this helps!

Thank you.

@Chandan.Maurya , thank you for the suggestion. This simple method that accomplishes what I was hoping to do.

@Mark.Nicholson. This is a good idea.

I have tested this by making a ‘Rectangle’ surface a detector with material set to ‘MIRROR’ and setting the coating to transmit 90% and reflect 10%. A single 1W ray seems to impart all 1W to the detector and the reflected ray has the expected 0.1W…

I may be missing fundamental with the above setup, but the benefit to Chandan’s approach is that the thin mask creates the desired reflection and the remaining energy is detected and can be absorbed which acts more ‘physical’. In this case I see the expected 90% detected and 10% reflected.

Hi Mark,

Yes, its the second ‘1’ in row 6 of the merit function.