Dear Vik, Please, find in the attached file a presentation that clarifies the relation between the « ULTRASPEC – TNT » opto-mechanical interface and the ZEMAX model. We have verified that the CAD model and the ZEMAX model of the TNT are in good agreement. In particular, we have verified that : The mechanical distance between the cube ouput (ULTRASPEC mounting flange plane) and the M4 apex is equal to 250 mm. This is the case for all Instrument cube outputs as indicated in the TNT documentation and mechanical drawings. The distance between M1 vertex and M4 vertex is equal to d = 2556.6 mm +/- 0.1 mm. We conclude that the TNT ZEMAX optical model and the CAD mechanical model are in good agreement with a precision in the 100 µm range. Could you please clarify the statement « the distance from the primary vertex to the flange upon which Ultraspec is to be mounted is 2206.66 mm » ? A drawing would be welcomed. Let’s hope that these clarifiations will help you to update the ULTRASPEC ZEMAX model and optical performance. Please, tell me if you need additionnal information. Best regards. Christophe National Astronomical Research Institute of Thailand (NARIT) Siriphanich Building 191 Huay Kaew Road Chiang Mai 50200 - Thailand De : vik.dhillon1@gmail.com [vik.dhillon1@gmail.com] de la part de Vik Dhillon [vik.dhillon@sheffield.ac.uk] Date d'envoi : mercredi 21 août 2013 19:16 À : Christophe Buisset Objet : RE : TNT ZEMAX surface data Hi Christophe, Our optical designer needs one more piece of information not in the zemax file to check that everything is ok with ultraspec. He asks for the following.... --- > Can you find out if the distance from the primary vertex to the flange upon which Ultraspec is to be mounted is 2206.66 mm. That is the distance (according to the Zemax model provided) from the primary vertex to the wide field camera mounting flange, and so the distance to the Ultraspec mounting flange may not be the same. If it isn't, then I need to know because it will determine the flange to focus distance. The distance must be in the telescope engineering documentation. Once I have that information we can decide to either live with the refocus, or shim. --- Do you think you could find out the above information? Many thanks! Vik Christophe Buisset christophe@narit.or.th via sheffield.ac.uk Attachments20/08/2013 to Vik, Andrea, Saran Dear Vik Please, find in the attached file the ZEMAX file of the as-built telescope. The ZEMAX file comprises the TNT optical elements from the spider (telescope entrance) to the cube output. Please, find hereafter the answers to the optical designer requests : 1. primary radius of curvature and conic : Radius of curvature R1 = -7203.5, conic c1 = -1.013 (ZEMAX coordinate). 2. secondary radius of curvature and conic : Radius of curvature R2 = -1836.8, conic c2 = -1.954 (ZEMAX coordinate). 3. inter-mirror spacing M1 vertex to M2 vertex for best focus : the term « best focus » is not clear since it depends on the instrument placed at the TNT focal plane. Could you please clarify the optical configuration for which the « best focus » refers to ? In the provided ZEMAX file, the position of M2 has been adjusted in order to optimise the spot size for one of our instrument ( « ARC camera » instrument in the present case). 4. primary vertex to telescope nominal focus distance for best focus : please, refer to the ZEMAX file by taking account of the previous remarks. 5. secondary mirror focus range : According to the TNT Technical Specifications , the focus range is specified to be equal to “10 mm travel of the secondary mirror M2”. According to the OPD team the M2 can be translated by roughly +/- 10 mm from the best focus obtained for the current instruments. From your side, could you please also send us the ULTRASPEC ZEMAX file as well as all the input information you used to design this instrument ? These data are particularly important for us to cross-check the ULTRAPSEC optical interface and performance. Best regards. Christophe National Astronomical Research Institute of Thailand (NARIT) Siriphanich Building 191 Huay Kaew Road Chiang Mai 50200 - Thailand ________________________________________ De : vik.dhillon1@gmail.com [vik.dhillon1@gmail.com] de la part de Vik Dhillon [vik.dhillon@sheffield.ac.uk] Date d'envoi : lundi 19 août 2013 15:22 À : Christophe Buisset Cc: Andrea Richichi; Saran Poshyachinda Objet : Re: TNT ZEMAX surface data Hi Christophe, I passed the optical prescription for the telescope that you sent me onto our optical designer and he is now very concerned: it appears to be very different to the one that we were originally sent and that we built our ULTRASPEC optics to. He has asked for the following information: --------------- "I need the following from the observatory as a matter of urgency: a Zemax file or text file with a model of the optics, as-built, that contains the following information: 1. primary radius of curvature and conic, 2. secondary radius of curvature and conic, 3. inter-rmirror spacing M1 vertex to M2 vertex for best focus, 4. primary vertex to telescope nominal focus distance for best focus, 5. secondary mirror focus range. Also, it would be preferable to receive an official document giving the telescope prescription that has been provided by the manufacturer to the Thais, if it can be made available." --------------- Would you be able to send us this as soon as possible, please? Thanks, Vik. Vik Dhillon phone: +44 114 222 4528 Dept of Physics & Astronomy fax: +44 114 222 3555 University of Sheffield email: vik.dhillon@sheffield.ac.uk Sheffield S3 7RH, UK web: www.shef.ac.uk/physics/people/vdhillon