Shay, I put an "anti-reflecting rubber placemat" underneath the glass wafer during exposure (Hard contact mode) I know, it is not quit an anti-reflective coating, but it does improve a lot. SEM images sometimes show that the channels close to the wafer are open- at least at the "intrances". It looks like a tunnel, but it is not clear if it is open all the way through the channel (10-20 um lang). Maybe it is not enough to suppress the reflections. Thanks for Your suggestion. Herman. ________________________________ Van: mems-talk-bounces@memsnet.org namens shay kaplan Verzonden: vr 8-6-2007 18:37 Aan: 'General MEMS discussion' Onderwerp: RE: [mems-talk] 2.5 um microchannels in SU-8 Sounds like reflections from the back of the glass Shay