UVIT Project Press Release

ReleasePhotek in conjunction with the Ultra-Violet Imaging Telescope (UVIT) has developed and manufactured the imaging tubes for one of five payloads on board the ASTROSAT spacecraft, India’s first satellite dedicated to multi-wavelength astronomy. The satellite is scheduled for launch in 2008 by the Indian Space Research Organisation (ISRO).

The aims of ASTROSAT involve multi-band observations in wavelengths extending from hard X-rays to the visible band to investigate the origin and mechanism of radiation emissions in active galactic nuclei.

UVIT aims to provide flux calibrated images of the sky at a spatial resolution of ~ 1.5 second of arc in two ultraviolet channels, far-UV (120-180 nm) and near-UV (180-300 nm), simultaneously with ~ 0.5 degree field of view. In addition to the two ultraviolet channels, simultaneous imaging is also done in part of the visible region (350-550 nm). The ultraviolet range of 120 - 300 nm and visible range of 350nm to 550nm would be covered through the use of broad and narrow band filters.

Three tubes will be flown, one for each of the spectral regions being studied. The detectors are 40mm photon-counting image intensifiers each with two microchannel plates and phosphor screen on a fibre optic taper. The tubes are fibre bonded to a FillFactory Star 250 CMOS Active Pixel Sensor. The high voltage power supplies for the imaging are being designed and manufactured by Mullard Space Science Laboratory in Surrey and system control software and electronics by Routes Astro-engineering in Canada.

The scientific aims of the mission require the tubes to have high sensitivity and resolution in the UV region. High resolution images are obtained by centroiding, however since the electron energy distribution and hence resolution of a proximity focussed intensifier is strongly wavelength dependent, extensive measurements and analysis have been made by Photek to ensure the flight model tubes meet the 30 microns resolution target.

A paper entitled “Wavelength-dependent resolution and electron energy distribution measurements of image intensifiers” was presented at the SPIE’s Optics and Photonics Conference, August 2006 (proceedings awaiting publication).