Top/NIR Channel/Detector


ANIR adopts an engineering grade PACE HAWAII-2 array detector, and uses only a single quadrant with 1024 x 1024 pixels. In a normal operation, the detector is cooled down to 70K.

TAC Readout Electronics

For the array readout, data acquisition system TAC is adopted, which is originally designed for mid-infrared arrays of MAX-38 camera. The TAC system consist of a real-time Linux PC equipped with a RTAI extension, and a digital I/O board PCI-2772c (Interface Co. Ltd.) with a DMA function. The front-end electronics consist of the fan-out board mentioned above and two VME full-size boards, that is a bias/clock board and an amplier/ADC board.

The advantage of this system is the flexibitily of the clock generation, which enables us to read out the array at any speed you want.

Readout Procedure

Typical readout mode is a correlated double sampling (CDS) of reset - read - read(reset all the frame first before the first readout), with pixel rate of 4usec/pix, which result in the shortest exposure time of 4.2sec. This can be accelerated up to 2usec/pix (or 2.1sec/frame), but the serious readout pattern occurs, and we recommend this mode to use only for bright objects.

There are following optional readout modes;

  • ResetRead Mode: Instead of typical reset - read - read procedure, reset_and_read - read readout is possible, where reset_and_read - read resets each row of the array before the readout. This will suppress the saturation of the frame, but some reset pattern occurs, so recommended to use only for bright targets.
  • Multiple Fowler Sample Mode is also possible to reduce the readout noise with long exposure time.
  • Ramp-up Sample Mode is possible not only to suppress the readout noise but also to get a wide dynamic range. In this mode, obtained frames will be processed after the acquisition, and all the pixels will be fitted within the range where the linearity is good to get the true flux even for the saturated flux. However, this mode is still experimental and user should consider its risk.

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Last-modified: 2009-09-25 (Fri) 00:09:26