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Chapter 3 - Payload Sensors
should be performed for every 20°C (68°F) change in subject temperature or every time the scene setup is
changed. Care should be exercised to select a scene with a varied range of thermal energy. For example, focusing
on the sun over water may skew the calibration.
2-Point Calibration
Utilizes two thermal signature profiles for calibration – a known temperature source followed by a scene based 1-
Point calibration. The lens has an internal, IR-blackened heat diode that is used as a variable temperature control
source. By measuring known temperatures of the control source, the system undergoes a complex recalculation of
its pixel Non-Uniformity Correction (NUC) tables – temporarily overriding the factory calibrated tables in memory.
The factory NUC table is restored when the turret is powered down.
Only use a 2-Point calibration if several 1-Point calibrations, with varied thermal scene changes, do not yield a
satisfactory result. The process takes approximately 100 seconds to complete and might actually degrade image
quality. Operators should exercise care and determine whether a 2-Point calibration is necessary because the result
will not match the calibration accuracy of sophisticated factory equipment.
Sensitivity. Controls the amount of thermal exposure, to the camera's focal plane array, that is needed to capture
video, and it has a function similar to the brightness control on a television or monitor. To control exposure,
operators can utilize either an Auto or Manual mode. In Auto mode, the system automatically controls image
brightness to maintain video quality over a range of thermal levels. In Manual mode, operators can manually
change brightness by making stepped adjustments to the sensitivity increment.
Offset. Sets the temperature offset value for the image and similar to the contrast control on a television or monitor.
Scene Setup. Controls thermal exposure of the entire video image and optimizes contrast based on three settings:
•
Default – a general purpose setting for most thermal conditions.
•
Low – a low contrast setting for a limited thermal range, e.g. a gray boat in rough water.
•
High – a high contrast setting for a wide thermal range, e.g. a dark plane in scattered clouds.
Note: After any scene setup change, operators must run a 1-Point calibration for the change to take effect.
Polarity. Inverts image polarity and sets tone priority for hot and cold objects:
•
Black Hot – hottest objects appear black and coolest appear white.
•
White Hot – hottest objects appear white and coolest appear black.
3.2.3
EON - MX-Day/Night Spotter™ Sensor
The Electro Optical Narrow (EON) sensor is a single lens with dual camera imaging capabilities - one daylight
priority and the other for low-light conditions. The daylight camera outputs color video while the low-light camera
outputs monochromatic video. The sensor consists of five main components:
•
a 3-CCD, daylight camera
•
a high sensitivity CCD, low-light camera
•
a fixed focal length lens
•
beam splitter optics for dual camera imaging
•
filters for camera selection and near infrared light wavelength priority
October 2007
60
TM00358 Rev. A
L-3 WESCAM
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