From hkessler@mail.cvilaser.com Thu Nov 8 14:43:00 2001 Date: Thu, 11 Oct 2001 15:49:13 +0100 From: Helmut Kessler To: 'Vikram Dhillon' Cc: 'Mark John Stevenson' , "'cbridle@tol-cvi.com'" , "'sberry@tol-cvi.com'" , 'Tom Marsh' Subject: RE: new dichroic curves Dear Vik Please find attached the slightly shifted curves that put the cut-off point into the correct position. Best wishes, Helmut -----Original Message----- From: Helmut Kessler [SMTP:hkessler@tol-cvi.com] Sent: 11 October 2001 10:10 To: 'hkessler'; 'Vikram Dhillon' Cc: 'Mark John Stevenson'; 'cbridle@tol-cvi.com'; 'sberry@tol-cvi.com'; 'Tom Marsh' Subject: new dichroic curves Dear Vik Please find attached the latest update on the dichroic coatings. These take into account our discussion we had yesterday. Please let me know what you think. Best wishes, Helmut << File: 503521-dichroic1.doc >> << File: 503521-dichroic2.doc >> -----Original Message----- From: hkessler [SMTP:hkessler@tol-cvi.com] Sent: 03 October 2001 16:12 To: 'Vikram Dhillon'; hkessler Cc: 'Mark John Stevenson'; 'cbridle@tol-cvi.com'; 'sberry@tol-cvi.com'; Tom Marsh Subject: RE: Correction -----Original Message----- From: Vikram Dhillon [SMTP:Vik.Dhillon@sheffield.ac.uk] Sent: 26 September 2001 16:12 To: hkessler Cc: 'Vikram Dhillon'; 'Mark John Stevenson'; 'cbridle@tol-cvi.com'; 'sberry@tol-cvi.com'; Tom Marsh Subject: RE: Correction Hi Helmut, Thank you very much for the theoretical dichroic curves. I have a few comments/questions: 1. The 50% cut point of dichroic 1 appears to be ~400nm, not 387.79nm. In fact, it looks like the cut in your curve STARTS at 387.79nm. What I suspect has happened here is that I did not explicitly state in our specifications that the cut-point refers to the 50%*T wavelength. Sorry about this. Could the curves be shifted accordingly? The same applies to dichroic 2. 2. The very first quote you sent me (dated 29/11/2000) had curves which exhibited a much sharper cut than the ones you just sent me. A sharp cut is very important to us. Would it be possible to have a sharper cut and say lose a bit of the blue wavelengths, i.e. move the blue limit to ~310-315nm from 300nm? There is also no need for the dichroic to reflect so well beyond 1000nm, so we would be prepared to lose a little there if it helps. Alternatively, we would even be willing to lose a little reflectivity, say from 99% to 98% (average) to achieve a really nice clean cut. Thanks for your help, Vik. ------------------------------------------------------------------------ ------- Vik Dhillon phone: +44 114 222 4528 Dept of Physics & Astronomy fax: +44 114 272 8079 University of Sheffield email: vik.dhillon@shef.ac.uk Sheffield S3 7RH, UK web: http://www.shef.ac.uk/~phys/people/vdhillon ------------------------------------------------------------------------ ------- [ Part 2, Application/MSWORD 32KB. ] [ Unable to print this part. ] [ Part 3, Application/MSWORD 32KB. ] [ Unable to print this part. ] From hkessler@mail.cvilaser.com Thu Nov 8 14:42:37 2001 Date: Wed, 3 Oct 2001 16:11:38 +0100 From: hkessler To: 'Vikram Dhillon' , hkessler Cc: 'Mark John Stevenson' , "'cbridle@tol-cvi.com'" , "'sberry@tol-cvi.com'" , Tom Marsh Subject: RE: Correction Hi Vik Thank you very much for your e-mail and my apologies for the delay in responding. I was on holidays for a few days last week. I had a look into the issue and corrected the cut-off wavelength on the coating designs. I also checked the first theoretical designs, and I have to admit that I had made a mistake on those - some layers were rather thin and the designs would be somehow difficult to manufacture as they would be very sensitive to small machine variations. I apologise for the mix-up. Please let me know what you think of the attached designs. Bst wishes, Helmut -----Original Message----- From: Vikram Dhillon [SMTP:Vik.Dhillon@sheffield.ac.uk] Sent: 26 September 2001 16:12 To: hkessler Cc: 'Vikram Dhillon'; 'Mark John Stevenson'; 'cbridle@tol-cvi.com'; 'sberry@tol-cvi.com'; Tom Marsh Subject: RE: Correction Hi Helmut, Thank you very much for the theoretical dichroic curves. I have a few comments/questions: 1. The 50% cut point of dichroic 1 appears to be ~400nm, not 387.79nm. In fact, it looks like the cut in your curve STARTS at 387.79nm. What I suspect has happened here is that I did not explicitly state in our specifications that the cut-point refers to the 50%*T wavelength. Sorry about this. Could the curves be shifted accordingly? The same applies to dichroic 2. 2. The very first quote you sent me (dated 29/11/2000) had curves which exhibited a much sharper cut than the ones you just sent me. A sharp cut is very important to us. Would it be possible to have a sharper cut and say lose a bit of the blue wavelengths, i.e. move the blue limit to ~310-315nm from 300nm? There is also no need for the dichroic to reflect so well beyond 1000nm, so we would be prepared to lose a little there if it helps. Alternatively, we would even be willing to lose a little reflectivity, say from 99% to 98% (average) to achieve a really nice clean cut. Thanks for your help, Vik. ------------------------------------------------------------------------ ------- Vik Dhillon phone: +44 114 222 4528 Dept of Physics & Astronomy fax: +44 114 272 8079 University of Sheffield email: vik.dhillon@shef.ac.uk Sheffield S3 7RH, UK web: http://www.shef.ac.uk/~phys/people/vdhillon ------------------------------------------------------------------------ ------- [ Part 2, Application/MSWORD 32KB. ] [ Unable to print this part. ] [ Part 3, Application/MSWORD 32KB. ] [ Unable to print this part. ]