L3 Communications MX-15i - IR Sensor; Table 3-2 IR Lens Capabilities

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Chapter 3 - Payload Sensors TM00358 Rev. A

October 2007 L-3 WESCAM

• For hot operation, the sensor will shutdown above 70°C and not restart until 60°C.

• For cold starts below -0°C, the sensor will not operate until it has been warmed.

Operator’s have the capability to control the following imaging parameters:

• Sensitivity

• Filters

• Initiate a BIT

Sensitivity. Controls the amount of light exposure to the camera CCD. The control is similar to the brightness

control on a television or monitor. However, the system makes proportional adjustments to three parameters:

• lens’s iris opening

• digital shutter speed

• electronic gain

To control light use, 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 light levels. In Manual mode, operators can

manually change brightness by making stepped adjustments to the sensitivity increment. The brightness range can

be adjusted between:

• least sensitivity, i.e. smallest iris opening, shortest shutter speed, and minimum electronic gain.

• most sensitivity, i.e. largest iris opening, longest shutter speed, and maximum electronic gain.

Filters. Selects range of light wavelength to extend viewing into a near infrared range. There are two filter positions:

• COL – restrictive pass filter to transmit visible spectrum only

• NIR – all pass filter to transmit near infrared range

3.2.2 IR Sensor

The infrared (IR) sensor is a thermographic imaging camera that outputs monochromatic video. This sensor forms

an image using infrared light much like a digital camera forms an image except using visible light. Instead of

measuring light in the visible spectrum wavelength range (450–750 nm), the IR sensor is sensitive to the mid-

infrared wavelength range (3.4–5.2 µm). The sensor consists of 2 main parts:

• camera

• a stepped zoom lens

Table 3-2 IR Lens Capabilities

Designation Focal Length Field of View

Minimum Focus

Distance

WFOV 27 mm 26.67° <3m (<10 ft)

MFOV 135 mm 5.43° <12.2m (<40 ft)

NFOV 675 mm 1.09° <243.8m (<800 ft)

VNFOV 2024 mm* 0.36° <243.8m (<800 ft)

*Optical focal length is 1012 mm. Apparent focal length achieves 2024 mm when a 2x electronic zoom is applied