Lens - VOLTCRAFT 2304480 Bedienungsanleitung

e) Lens
• The thermal imager has a lens.
• FOV (Field of View) is the largest area that the imager can see at a set distance.
• The horizontal FOV, vertical FOV and IFOV for the lens are as follows:
Focal length
22 mm
• IFOV (Instantaneous Field of View) is the smallest detail within the FOV that can be detected or seen at a set
distance (in rad units). The formula for calculating this is: IFOV = (Pixel Size) / (Lens focal length).
• D:S theoretical (= 1 / IFOV theoretical) is the calculated spot size based on the pixel size of the thermal imager
detector array and lens focal length.
Example: If the thermal imager uses a 22 mm lens and has a pixel size of 17 μm, a Horizontal FOV of 17 ° and
a Vertical FOV of 12.7 °, the IFOV is 17 μm / 22 mm = 0.77 mrad and the D:S theoretical (= 1 / IFOV theoretical)
= 1298:1.
3 8 4 m
2 8 8 m
• D:S measure (= 1 / IFOV measure) is the spot size needed to provide an accurate temperature measurement.
• Typically, the D:S measure is 2 to 3 times smaller than the D:S theoretical, which means the temperature
measurement area of the target needs to be 2 to 3 times larger than that determined by the calculated theoretical
D:S.
Note: IFOV theoretical represents the smallest objects that the thermal imager can detect or see. IFOV measure
represents the smallest object from which an accurate temperature can be measured by the thermal imager.
Horizontal FOV
17 °
Spot size = 100.00 cm x 100.00 cm
(Based upon IFOV theoretical)
1 2 9 8 m
Vertical FOV
12.7 °
17°
12.7°
IFOV
0.77 mrad
53