Hi I have a question on AOMs used in a double pass configuration. I understand the motivation for such a setup, but what I don't quite understand is the following: During the first pass, the frequency of the incoming beam is changed from ω to ω+Ω at an angle θB. Then we send the diffracted beam with frequency ω+Ω through the AOM once again at the same angle θB. This last part I don't quite undertand: How can the Bragg condition be satisfied for the angle θB at both ω and ω+Ω? Best regards, Niles.