TAFTS instrument specifications

ParameterValue
Interferometer Martin-Puplet, differential inputs and outputs
Spectral Coverage 800 cm-1 to 80 cm-1 in two bands
(a) 800 cm-1 to 330 cm-1 and
(b) 330 cm-1 to 80 cm-1
Filtration Dichroic filters to match detector responses
Resolution 0.1 cm-1
Optical path 100 mm (total OPD, for D/S interferograms) differential scan, four-fold gearing
Scan drive micro-stepping motor with pulley gearing system
Mirror carriage Kinematic: precision V-grooves, 3 ball bearings
Acceptance solid angle 6.28 x 10-4 steradians
Working Aperture dia. 25 mm (Area = 4.91 x 10-4 m2)
Beamsplitters
Optical System Reflective, cooled field and aperture stops
Outputs One pair differential outputs / spectral band
Detectors Two pairs of photoconductors cooled to 4K probably (a) Silicon BIB and (b) Ge:Ga
Scan time 2 S active, 2.5 seconds total
Optical path velocity 50 mm per second
Mirror velocity 25 mm per second
Fringe frequency bands 5000 Hz -- 1500 Hz and 2500 Hz -- 400 Hz
ADC Sampling rate fixed frequency 20 kHz / 10 kHz
Position measurement HeNe interferometer
Sample correction off-line digital filtering + phase correction
Sampling interval 2.5µ
Total signal samples 120,000 per scan (360,000 Bytes)
Laser timings 40,000 samples precise to 1 in 1024 or 2048
Total bytes per scan 440,000 over 2.5 secs.
ADCs 2 off Sigma-Delta 20 bit (Crystal CS 5390)
Data Rate (averaged) 172 kBytes / second (= 604 MByte / hour, 4.82 Gbyte / 8 hours)
Recording Medium 2 SCUSI Harddisk; 3.2G capacity each
Calibration Four on-board black body sources
Instrument Controllers Pentium PC, on-board 486 DX4/100 PC
Mass 80 kg (Interferometer) 27 kg (control box) 3 kg (disk box)
Environmental Down to -50 Centigrade, 50,000 feet Interferometer at ambient temp, evacuated some electronics at 10C, 1 atmosphere
Power Consumption 200 Watts + heaters (Up to 1 kW)