A dense grid of narrow bandpass steep edge filters for the JST/T250 telescope: summary of results

U. Brauneck; R. Sprengard; S. Bourquin; A. Marín-Franch

doi:10.1117/12.2272424

5 September 2017 A dense grid of narrow bandpass steep edge filters for the JST/T250 telescope: summary of results

U. Brauneck, R. Sprengard, S. Bourquin, A. Marín-Franch

Proceedings Volume 10401, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems; 104011A (2017) https://doi.org/10.1117/12.2272424
Event: SPIE Optical Engineering + Applications, 2017, San Diego, California, United States

Abstract

On the Javalambre mountain in Spain, the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA) has setup a new wide field telescope, the JST/T250: a 2.55 m telescope with a plate scale of 22.67”/mm and a 3° diameter field of view. To conduct a photometric sky survey, a large format mosaic camera made of 14 individual CCDs is used in combination with filter trays containing 14 filters each of theses 101.7 x 96.5 mm in size. For this instrument, SCHOTT manufactured 56 specially designed steep edged bandpass interference filters which were recently completed. The filter set consists of bandpass filters in the range between 348,5 nm and 910 nm and a longpass filter at 915 nm. Most of the filters have FWHM of 14.5 nm and a blocking between 250 and 1050 nm with optical density of OD5. Absorptive color glass substrates in combination with interference filters were used to minimize residual reflection in order to avoid ghost images. Inspite of containing absorptive elements, the filters show the maximum possible transmission. This was achieved by using magnetron sputtering for the filter coating process. The most important requirement for the continuous photometric survey is the tight tolerancing of the central wavelengths and FWHM of the filters. This insures each bandpass having a defined overlap with its neighbors. In addition, the blocking of the filters is better than OD5 in the range 250–1050 nm. A high image quality required a low transmitted wavefront error (</4 locally and </2 on the whole aperture) which was achieved even by combining 2 or 3 substrates. We report on the spectral and interferometric results measured on the whole set of filters. λλ

Citation Download Citation

U. Brauneck, R. Sprengard, S. Bourquin, and A. Marín-Franch "A dense grid of narrow bandpass steep edge filters for the JST/T250 telescope: summary of results", Proc. SPIE 10401, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems, 104011A (5 September 2017); https://doi.org/10.1117/12.2272424

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
13 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Optical filters

Bandpass filters

Telescopes

Absorption filters

Interference filters

Wavefronts

Astronomy

Show All Keywords

Keywords/Phrases

Search In:

Publication Years