Proceedings Article | 10 August 2010
Proc. SPIE. 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave
KEYWORDS: Optical components, Reflectors, Scattering, Sensors, Calibration, Tungsten, Lamps, Diffusers, Optical simulations, Camera shutters
The Euclid dark energy mission is currently competing in ESA's Cosmic Vision program. Its imaging instrument,
which has one visible and one infrared channel, will survey the entire extragalactic sky during the 5 year mission.
The near-infrared imaging photometer (NIP) channel, operating in the ~0.92 - 2.0 μm spectral range, will be
used in conjunction with the visible imaging channel (VIS) to constrain the nature of dark energy and dark
matter. To meet the stringent overall photometric requirement, the NIP channel requires a dedicated on-board
flat-field source to calibrate the large, 18 detector focal plane.
In the baseline concept a 170 mm Spectralon diffuser plate, mounted to a pre-existing shutter mechanism
outside the channel, is used as a flat-field calibration target, negating the need for an additional single-point-failure
mechanism. The 117 × 230 mm focal plane will therefore be illuminated through all of the channel's
optical elements and will allow flat-field measurements to be taken in all wavelength bands. A ring of low power
tungsten lamps, with custom reflecting elements optimized for optical performance, will be used to illuminate
the diffuser plate.
This paper details the end-to-end optical simulations of this concept, a potential mechanical implementation
and the initial tests of the proposed key components.
