InfraTec VarioCAM User Manual page 10

Thermographic system of resolution (640 x 480) pixels
lens
wide-angle lens
standard lens
telephoto lens 1
telephoto lens 2
telephoto lens 3
close-up lens
close-up 0.17x
close-up 0.5x
microscopic lens 1.0x
Detector
The VarioCAM ® hr head has an uncooled microbolometer FPA detector (uncooled Focal Plane Array).
The detector is thermally stabilised with high precision using a Peltier element and is thus independent of
the ambient temperature.
The various elements of the detector are microscopically minute thin-film resistors on wafer-thin
membranes, which are arranged cantilevered a few micrometers above the silicon read-out circuit. The
thermal radiation of the scene is imaged by the lens of the thermographic system on these detector
elements and absorbed by them. The temperature change of the detector elements resulting therefrom
yields electronically evaluable signals which can be read out line-wise and column-wise by a read-out
circuit.
Applying an uncooled detector guarantees quick availability of the camera function after switching it on
(start-up time < 60 seconds) and long service life (MTTF) in permanent use.
Detector electronics
The detector electronics supplies the BIAS voltages required for detector operation and further control
signals, and it takes care of the pre-processing and digitalisation of the analog video output signal from
the detector.
Image processing electronics
Real-time image processing with the following essential functions (depending on the equipment) is
implemenmted with the help of an FPGA (Field Programmable Gate Array) and an embedded PC
(modular compact internal PC):
■ Detector electronics interface
■ Gain and offset correction
■ Defective pixel treatment
■ Low-pass filtering
■ Zoom generator
■ Graphic overlay
■ FireWire (IEEE 1394) interface
■ Embedded PC interface
■ Standard-format video-image generator (PAL/NTSC-FBAS, S-Video, RGB)
6
focal length (mm) min. focus (m)
12.5
30
50
75
130
focal length (mm)
for 30
for 30
-
© InfraTec GmbH 2015
User Manual for the Thermographic System VarioCAM
IFOV (mrad)
0,2
0,3
2,0
2,0
5,0
focus (mm) field of view (mm²)
150
50
50
®
hr head
3. Technical Description
FOV (°)
2.0 (65 x 51)
0.8 (30 x 23)
0.5 (18 x 14)
0.3 (12 x 9)
0.2 (7 x 5)
resolution (μm)
(80 x 60)
(27 x 20)
(16 x 12)
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