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    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/042/0041

    • Keywords

       

      Molecular contamination; ultraviolet optics; space optics; transmission measurements—; ultra high pure (UHP) nitrogen purging.

    • Abstract

       

      Ultra Violet Imaging Telescope (UVIT) is one of the 5 instruments on AstroSat satellite, which was launched on September 28, 2015. UVIT was designed to make images with a resolution of <1:8$''$, simultaneously in two ultraviolet channels: Far Ultraviolet (130–180 nm) and Near Ultraviolet (200–300 nm). Images are also made in visible region (320–550 nm) for tracking drifts in pointing. The shortest wavelengths to be observed with UVIT can be heavily absorbed by mono-molecular deposits/contamination on the optical surfaces.Keeping contamination under control in UVIT was a major challenge and it required a variety of actions: (i) strict control of the payload materials and process, (ii) mechanical configuration, (iii) baking of all the parts to release all the adsorbed molecules etc., (iv) assembly in ultra cleanrooms, (v) pre-inspection and auditing of all the areas, in which UVIT was placed, for any potential for contamination, (vi) continuous purging, with ultrapure nitrogen gas, till a few days before the launch, etc. In order to minimise any possible cross contaminationsfrom the other payloads/satellite, the doors of UVIT were opened 2 months after the launch. The high performance in the orbit and high stability of the sensitivity over 4 years in the orbit shows that the contamination was negligible. This paper presents the processes and protocols followed during the integration and testingphase to minimise the contamination in order to prevent any performance degradation.

    • Author Affiliations

       

      S. KATHIRAVAN1 S. N. TANDON2 B. RAGHAVENDRA PRASAD1 S. SRIRAM1 A. PRADEEP1 T. VISHNU1 P. K. MAHESH1 P. U. KAMATH1 S. NAGABHUSHANA1 AMIT KUMAR1

      1. Indian Institute of Astrophysics, Bangalore 560 034, India.
      2. Inter University Centre for Astronomy and Astrophysics, Pune 411 007, India.

    • Dates

       
      Published
      11 June 2021
      Manuscript received
      29 October 2020
      Accepted
      6 December 2020
      Final version published online
      11 June 2021

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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