Borstad Associates Ltd. - Compact Airborne Spectrographic Imager (CASI)

Compact Airborne Spectrographic Imager (CASI)

We have developed our own small strap-down airborne system, which includes differential GPS navigation and control, 3 axis geo-correction and a Compact Airborne Spectrographic Imager (CASI) developed by Itres Instruments, built in 1990 and upgraded in 1994 to improve its blue sensitivity.

Our CASI is a small, but extremely flexible multispectral imager operating in the visible and near infra-red [ 405 to 916 nm] region of the spectrum, which can be configured for quantitative digital mapping of marine or terrestrial targets. Up to 15 programmable spectral channels of image data with pixel sizes between 2 and 4 m can be acquired using an unpressurized aircraft. For assignments with requirements for more spectral channels, smaller pixels or more infra-red capability, we also rent more recent versions of the instrument with slightly different specifications. The system is transported as cargo to the client's site, and then quickly mounted in an unmodified local aircraft.

SPECIFICATIONS OF THE BORSTAD ASSOCIATES LTD. COMPACT AIRBORNE SPECTROGRAPHIC IMAGER (CASI)

Spectral:	coverage number of pixels resolution	403 to 914 nm 288 1.8 nm
Spatial:	coverage number of pixels resolution	35 degrees with one camera 512 1.2 mRadian
Modes	spatial	up to 15 spectral bands formed from spectral pixels, but the number of bands governs integration time [Int = 17.5 + Bands*5.5]. The choice of pixels is under software control. A push-broom image 512 pixels wide is formed in each band.
	spectral	spectra covering 403 to 914 nm with 1.8 nm resolution are recorded from up to 39 different 'look directions' across the swath (variable spacing). Number of look directions governs integration time).
Integration times		75 msec (spatial), 150 msec (spectral) typical (depends on signal level)
Digitization		12 bits on chip
Data recording		Exabyte (TM) digital recording on 8 mm 2 Gigabyte data tapes at 280Kbit/s
Borstad Auxiliary equipment		two axis mechanical gyro, Leica GPS receiver single broad band illumination sensor on top of aircraft recording to onboard 80486 computer. Base station Leica GPS receiver to allow differential correction.
Weight		75 Kg
Size	Camera head Instrument Control Unit Power supply unit Auxiliary computer Video monitor	15 x 22 x 22 cm 46 x 48 x 13 cm 46 x 48 x 11 cm 46 x 48 x 15 cm 46 x 10 x 33 cm
Power		110V 2.5A (18 Amps 28V through 800 Watt Flitetronics DC/AC inverter)