From t-kimura@asahi-spectra.co.jp Thu Sep 21 11:09:06 2006 Date: Thu, 21 Sep 2006 19:08:44 +0900 From: Toshihiko Kimura To: Vik Dhillon Cc: Jorge Casares Velazquez , Danny Steeghs Subject: Specifications(Halpha/Blue continuum) Dear Dr.Vik, 1)Bandpass film design We have finished analyzing the optical system of ULTRACAM's f/2.3 converging beam. In accordance with Zemax file you sent me, we found the beam with 9.25 deg.was the most dominant. > Designed for operation in ULTRACAM's f/2.3 converging beam > at 0 degrees centigrade [Halpha] CWL 658.5nm (+2.3nm) in collimated beam => CWL 656.2nm in ULTRACAM's f/2.3 converging beam [Blue continuum] CWL 516.8nm (+1.8nm) in collimated beam => CWL 515nm in ULTRACAM's f/2.3 converging beam 2)Filter construction Actually I have two kinds of descriptions about optical thickness, which Dr.Vik sent to me. RFQ for CIII/NIII+HeII in 2003 ---------------------------------------------------------------- * Filter thickness - depends on subtrates used, but must provide equivalent optical thickness to 5.4mm of fused silica (i.e. the "clear" filters you recently provided for us). Tolerance on thickness is +/- 0.05mm. RFQ for Halpha in 2006 ---------------------------------------------------------------- - Thickness: equivalent *optical* thickness to the SDSS r' filter you previously supplied us with I understand both descriptions mean the same. This time we can get Zemax file and know the optical system more correctly. According to our calculation, [Halpha] Fused silica(2mm) + RG610(1.33mm) + Fused silica(2mm) -Polishing tolerance : all +/-0.025mm -Physical thickness tolerance : 5.33mm +/-0.1mm [Blue continuum] Fused silica(2mm) + BG39(1.33mm) + Fused silica(2mm) -Polishing tolerance : all +/-0.025mm -Physical thickness tolerance : 5.33mm +/-0.1mm 3)Size tolerance > Size: 50x50mm +0, -0.1mm substrates > How about 50x50mm +/-0.1mm ? => I think +0.1/-0.1mm is acceptable for you. If you have any questions, please ask me. Best regards, Toshihiko