Actual transmission data(HiPERCAM Halpha very narrow filter) Toshihiko Kimura 18 June 2020 at 06:25 To: Vik Dhillon , Jorge Casares Velázquez Cc: mapt@iac.es Dear Prof. Dhillon, Prof. Casares, I send the actual transmission data of the Halpha very narrow filter for the HiPERCAM today. > The size of the HiPERCAM filter is 50 mm x 50 mm, not large. > However, we measured the transmission at 5 locations over the clear > aperture in consideration of the requested CWL tolerance, +/-0.5 nm. As the Halpha very broad filter, we measured the transmission at five locations over the clear aperture. [HiPERCAM Halpha very narrow filter] In a parallel beam at AOI 0 deg, Location 1 CWL: 657.8 nm / FWHM: 2.8 nm Location 2 CWL: 657.8 nm / FWHM: 2.8 nm Location 3 CWL: 657.8 nm / FWHM: 2.8 nm Location 4 CWL: 657.8 nm / FWHM: 2.8 nm Location 5 CWL: 657.6 nm / FWHM: 2.8 nm Averaged CWL of 5 locations is 657.76 nm. > 657.76 - 1.53 = 656.23 nm in an f/2.47 beam at HiPERCAM + WHT > 657.76 - 0.77 = 656.99 nm in an f/3.465 beam at HiPERCAM + GTC > 657.76 - 1.77 = 655.99 nm in an f/2.3 beam at ULTRACAM Halpha very narrow filter meets our proposed specifications including out-of-band transmission. Sincerely, Toshihiko On 2020/05/29 15:07, Toshihiko Kimura wrote: Dear Dr. Torres, CC Prof. Dhillon, Prof. Casares, I will send the actual transmission data of the Halpha extremely broad (35 nm) filter for the HiPERCAM today. > In consideration of requested wavelength tolerance and 35 nm FWHM, > or filter size, we measured the transmission only at the center location. CWL is 658.30 nm and FWHM is 35.0 nm in a parallel beam. > 658.30 - 2.01 = 656.29 nm in an f/2.47 beam at HiPERCAM + WHT > 658.30 - 1.02 = 657.28 nm in an f/3.465 beam at HiPERCAM + GTC > 658.30 - 2.33 = 655.97 nm in an f/2.3 beam at ULTRACAM The peak transmission exceeds 99%. And the shape of passband is perfect, like "top-hat". Halpha extremely broad filter meets our proposed specifications including out-of-band transmission completely. Sincerely, Toshihiko From: Toshihiko Kimura Sent: Monday, May 25, 2020 3:27 PM To: mapt@iac.es Cc: Vik Dhillon ; Jorge Casares Velázquez Subject: Actual transmission data(HiPERCAM Halpha very broad filter) Dear Dr. Torres, CC Prof. Dhillon, Prof. Casares, According to the DHL tracking page, the customs clearance was completed last Thursday. > The IAC has started to handle the reception of some goods on Thursdays > and in the morning. I hope the package will be delivered to the IAC on 28 May. By the way, I will send the actual transmission data of the Halpha very broad (15 nm) filter for the HiPERCAM today. I asked our staff to mark each filter-name on one edge for identification. The size of the HiPERCAM filter is 50 mm x 50 mm, not large. However, we measured the transmission at 5 locations over the clear aperture in consideration of the requested CWL tolerance, +/-0.5 nm. You can get the same transmission performance by the incident beam from both directions. [HiPERCAM Halpha very broad filter] In a parallel beam at AOI 0 deg, Location 1 CWL: 658.0 nm / FWHM: 15.2 nm Location 2 CWL: 657.8 nm / FWHM: 15.2 nm Location 3 CWL: 658.0 nm / FWHM: 15.2 nm Location 4 CWL: 658.0 nm / FWHM: 15.2 nm Location 5 CWL: 658.0 nm / FWHM: 15.2 nm Averaged CWL of 5 locations is 657.96 nm. => 657.96 - 1.95 (bluer shift) = 656.01 nm in an f/2.47 beam at the HiPERCAM (Spec: 656.3 nm +/-0.5 nm in an f/2.47 beam) The peak transmission exceeds 99%. And the shape of passband is definitely perfect. Halpha very broad filter completely meets our proposed specifications including out-of-band transmission. Sincerely, Toshihiko From: Toshihiko Kimura Sent: Monday, December 16, 2019 11:48 AM To: Vik Dhillon Cc: Jorge Casares Velázquez Subject: Quotation(New Halpha filters for HiPERCAM) Dear Prof. Dhillon, I will send a quotation about new Halpha filters (very narrow, very broad, extremely broad) for the HiPERCAM today. I quoted 2 pcs for each, but on the basis of the optimization for an f/2.47 beam at the HiPERCAM. Halpha very narrow filter is quite sensitive for angle of incidence due to very narrow band-width. Eventually, peak transmission in an f/2.3 beam (ULTRACAM) is lower than in an f/2.47 beam. I'm now aware that I asked our engineer to make transmission model on the basis of f/2.45 beam, but it should be an f/2.47 beam. I think the difference is negligible, but just in case, I will ask him to check, especially about very narrow Halpha. [Proposed Specifications] 1)Coating method Magnetron sputtering method 2)CWL Very narrow: 656.3 nm +/-0.3 nm in an f/2.47 beam Very broad: 656.3 nm +/-0.5 nm in an f/2.47 beam Extremely broad: 656.3 nm +/-1 nm in an f/2.47 beam 3)FWHM We would like to suggest the FWHM specification in a parallel beam. Very narrow: 2.7 nm +/-0.3 nm in a parallel beam => 3.4 nm +/-0.3 nm in an f/2.47 beam Very broad: 14.9 nm +/-1 nm in a parallel beam => 15.0 nm +/-1 nm in an f/2.47 beam Extremely broad: 35.1 nm +/-3 nm in a parallel beam => 35.0 nm +/-3 nm in an f/2.47 beam 4)Peak transmission We would like to propose the specification of peak transmission for all in a parallel beam. T > 90% in a parallel beam 5)Blocking T < 0.01% 300 nm - 1100 nm 6)Substrate Monolithic fused silica 7)Size 50 mm x 50 mm +0, -0.1 mm 8)Clear aperture 48 mm x 48 mm 9)Thickness 5.43 mm +/-0.025 mm 10)Parallelism < 30 arc sec 11)Transmitted wavefront error (TWF) p-v lambda/4 per any 25 mm patches over the clear aperture prior to coating Our Zygo laser interferometer is equipped with HeNe laser (632.8 nm). But HeNe laser doesn't transmit through the Halpha filters, thus it is not possible to measure the TWF after coating. But thanks to a monolithic substrate structure, the initial TWF will be maintained after coating. 12)Scratch-dig 60-40 Sincerely, Toshihiko ------------------------------------------------------ > From: Vik Dhillon > Sent: Friday, November 15, 2019 9:07 PM > To: Toshihiko Kimura ; Casares Jorge > Subject: New Halpha filters for HiPERCAM > > > Dear Toshihiko, > > I hope all is well with you. > > My colleague, Prof. Jorge Casares (Instituto de Astrofisica de Canarias) > and I would like to buy a new set of Halpha filters for HiPERCAM. I think > I will be the person who will pay for the filters. > > These filters should be the same dimensions and specifications as the > existing "Super-SDSS" HiPERCAM filters that you made for us. This includes > being the same optical thickness as our existing filters so that the focus > doesn't change when we switch between the Super-SDSS filters and these new > Halpha filters. > > We would like the new Halpha filters to have the following central > wavelength and FWHM: > > - Halpha very narrow: FWHM=3.3 +- 0.3 nm CWL=656.3 +- 0.3 nm > - Halpha very broad: FWHM=15.0 +- 1.0 nm. CWL=656.3 +- 0.5 nm > - Halpha extremely broad: FWHM=35.0 +- 3.0 nm CWL=656.3 +- 1.0 nm > > (I name them like this because you have previously supplied me with > "Halpha narrow" FWHM=5.4nm and "Halpha broad" FWHM=9.3nm). > > I realise that some of these filters have quite challenging tolerances! > > We would like to buy 2 of each of these filters, assuming this is > approximately the same price as buying just 1 of each? Please could you > provide us with a quotation for these filters? > > Regards, > > Vik. > > --- > Prof. Vik Dhillon, Dept of Physics & Astronomy, Univ of Sheffield, > Sheffield S3 7RH, UK > +44 114 222 4528; www.vikdhillon.staff.shef.ac.uk > --- HiPERCAM Halpha very narrow filter.xlsx 335K View as HTML Download