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Pocket Guide

Fig.1.-Projection of focal plane onto bolometer arrays Credit:MPE

Fig.2.-Bolometer matrices assembly.Credit:MPE

Imaging Photometer

- Simultaneous two-band (same field of view, 3.5'x 1.75' ).
The long-wavelength is observing 130-210µm and
short-wavelength 60-85/85-130 µm
(selected in front of the blue bolometer array)
- Two filled bolometer arrays: 32x16 (red) and 64x32 pixels (blue)
- Point source sensitivity: ~3 mJy (5-sigma limit in 1 hour)


Photometer description
After the intermediate focus provided by the entrance optics, the light is split into the longwavelength and short-wavelength channels by a dichroic beamsplitter with a transition wavelength of 130 µm and is re-imaged with different magnification onto the respective bolometer arrays. The photometer uses two filled Si bolometer arrays with 16x32 and 32x64 square pixels to perform imaging photometry in two simultaneous bands, 60-85 µm or 85-130 µm and 130-210 over a field of view of ~1.75'x3.5', with full beam sampling in each band. The two short-wavelength bands are selected by two filters with a filter wheel. The incident infrared radiation is registered by each bolometer pixel as a tiny temperature difference.

Filters.- The PACS filters, in combination with the detectors, define the wavelength bands of the instrument. There are in total 3 bands in the PACS spectrometer: 60-85 µm, 85-130 µm and 130-210 µm.

Band
 Center Wavelenght (µm) Filter band
 Array FOV (arcmin)/(pixels)
Red 170 130-210 1.8' x 2.8'/ 16 x 32 pixels
Blue 1 110 90-130 0.9' x 1.4'/ 32 x 64 pixels
Blue 2 75 57-90 0.9' x 1.4'/ 32 x 64 pixels

Bolometer arrays
The figure 2 shows a cut-out of the 64x32 pixel bolometer array assembly. 4x2 monolithic matrices of 16x16 pixels are tiled together to form the short-wave focal plane array.

The cooler.
The instrument operates at sub-Kelvin temperatures, which are achieved using a 3He cooler.

Credits

The contents of this page are based on the PACS observer's Manual produced by Bruno Altieri, Roland Vavrek and the PACS Instrument Control Centre

For more information, see Observer Manual

Go back to PACS Instrument page

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This file was last modified on 21 May 2007 .