Operation Details - Metrel Md 9930 Benutzerhandbuch

MD 9930 Thermal camera

5. Operation details

Lens and camera field of view
This table lists the horizontal Filed of view (FOV), vertical FOV and IFOV for lens.
Focal Length
9 mm
IFOV (Instantaneous Field of View) is the size of the object caught in the single pixel
on the detector. It is given as spatial angle with unit mrad. It depends on the lens and
detector size.
DTS is distance to a measured object caught in a single pixel. It is the
theoretical
distance at which the given object's temperature can be theoretically measured. At
unity distance, the IFOV can be then directly translated to the object's size.
For accurate temperature measurement, the spot has to be about three times the
size of than at DTS
EXAMPLE:
120m
The FOV of the camera is 21° x 21°, which is about 0.36 x 0.36 rad. The detector
resolution for this example is 80 x 80 pixel. Each pixel then covers about 4.53 mrad,
which is IFOV. This means that at 1 m distance, each pixel is covering 4.53 mm
actual space. Temperature can be accurately measured on about 13.6 mm
distance. If turned the other way, DTS can be the calculated distance at which each
pixel will cover 1 m
7.5 mm lens, so knowing the IFOV gives the pixel size of the detector as 34 μm
Focus
To adjust focus rotate the IR lens clockwise or anti-clockwise. When target comes
into focus, it shows a sharp image. When the target moves out of focus, the thermal
image becomes blurry.
Horizontal FOV
19°
, or the distance to it must be 3 times shorter.
theoretical
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Spot size 1m x 1m
120m
220m
2
space, which is about 220 m. Thermal camera uses for example
Vertical FOV
25°
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19°
25°
11
Operation details
IFOV
2.78 mrad
2
2
at 1m
2
.