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Chapter 2. ICL 19
High-Speed Spectroscopy
This script uses a frame-transfer device (the CCD37-10 CCD) to perform high-speed spectroscopy. It collects a
spectral image in the image array, and bins that image down to a single line, as it shifts it into the storage area.
THIS REQUIRES A FACTORY MODIFICATION TO THE CAMERA (SEE BELOW). The camera immediately
performs another exposure, bins it, etc.
A total of 544 binned spectra are accumulated in the storage array, then read out. (Although the CCD37-10
image array is 512x512, the storage array is 512x544.) Each spectral line has a total exposure time of about 1.23
milliseconds, so this gives 2/3 of a second of continuous, high-speed spectral monitoring, with nearly a
millisecond time resolution.
script_begin();
shutter_open();
clear_parallel(2); /* this clears both image and storage */
expose(1); /* compensate for the first exposure time */
loop_begin(544); /* LOOP FOR EACH SPECTRUM / EACH ROW IN STORAGE */
expose(0); /* total exposure time: (0 + 1.23) milliseconds */
shift_mode_s(); /* shift the storage array only */
shift(1); /* move storage down 1 line, to make way for... */
shift_mode_s_alt(); /* custom setting: shift IMAGE ARRAY ONLY */
shift(512); /* bin entire image array into top of storage */
/* NOTE: this shift takes 1.23 milliseconds */
loop_end();
shutter_close(); /* DONE EXPOSING, NOW READOUT */
pixel_readout(0,512,1,544,1); /* read out the entire storage array */
loop_begin(544);
pixel_display(512,1); /* display data as 512 separate lines */
loop_end();
script_end(0);
FACTORY MODIFICATION: For high-speed spectroscopy, the CCD must be able to shift ONLY the image
array. (This accomplishes binning where charge accumulates on the top row of the storage array.) In this case,
the new shift table is loaded into one of the alternate shifting modes. Specifically,
shift_mode_s_alt()
is
reloaded, so it performs: A parallel shifting mode, this shifts the IMAGE array only on a frame-transfer CCD.
It should be called shift_mode_I_alt(), but that choice is not available.