From monnier@umich.edu Wed Jun 8 11:42:09 2005 Date: Tue, 7 Jun 2005 13:55:13 -0400 (EDT) From: John Monnier To: "Stevenson, Keith" Cc: John Monnier , Nathalie Thureau Subject: RE: Request for Quote for GRISM Keither, The efficiency for both of these is acceptable according to PC_GRATE. I don't know if you can confirm these numbers, but the transmitted efficiency in order 1 is >~60% from 1.5-2.4 microns for both. Does this seem reasonable? They said you often have make your custom prisms for grisms and suggested I try to order the full grism through you directly. So -- Here goes a nother round of specifications [you can ignore my email from yesterday]. All Grisms should use Schott IRGn6 glass (N~1.57 at 1.65 microns to match resin). The substrate should be circular, with outer diameter 25mm and with the thickest part of the prism <15mm. Best to make the 'thin' edge of the prism ~2mm and let the apex angle determine the thickness. I will also need broad band AR coating on each piece. Wavefront quality will need to be lambda/20 rms at 1.5 microns. Grism 1. -------- Using 53-*-135R -type grating 31.7 grooves/mm, blaze 6.18 degs apex for prism : undetermined.. but around 6.9 degs Grism 2 ------- Using 53-*-821R type grating 90 grooves/mm, blaze 17.5degs apex for prism: undetermined but around 17.5degs > ------------------------------------------------- John D. Monnier, Assistant Professor of Astronomy University of Michigan 941 Dennison Building 500 Church Street Ann Arbor, MI 48109-1090 monnier@umich.edu 734-763-5822 (FAX 734-763-6317)