IFOV is measured in which unit?

• A. Degrees
• B. MRAD
• C. Pixels
• D. Lumens

Answer: (B)

IFOV is the angular size that a single detector element (one pixel) covers in the scene. Since it’s an angle, it’s expressed in angular units. In infrared camera specs, this small-angle measure is typically given in milliradians (MRAD) because the angles involved are tiny and MRAD provides a convenient, precise scale for describing how much of the scene each pixel captures.

For example, if the IFOV is 2 MRAD and you’re 10 meters away, the linear width seen by one pixel is roughly 10 m × 0.002 ≈ 20 mm. This illustrates how IFOV connects distance to the area a pixel resolves.

Degrees is also an angular unit, but MRAD is the standard used here due to the very small angles involved in detector pixel coverage. Pixels and lumens are not angular units—pixels are image elements, and lumens measure light output.