# Field of view

Field of view (FOV) is the angle size of the scene which can be seen by the operator through the optical device under test.

This procedure requires a pinhole target and a motorized stage on which the UUT must be attached.

The horizontal field of view (HFOV) is measured by the user moving the stage to align the vertical line of the center of the pinhole with the left border of the image \theta_\text{left} and then the same is done with the right border of the image \theta_\text{right} .

For the vertical field of view (VFOV) measurements steps are the same, but instead of right and left borders of the image user aligns the horizontal line of the center of the pinhole with the top border of the image \theta_\text{top} and then with the bottom border of the image. \theta_\text{bottom} .

HFOV and VFOV are calculated by the formulas below:

\textbf{HFOV (mrad)}= \left| \theta_\text{right} - \theta_\text{left} \right| \times \frac{\pi }{180} \times 1000

\textbf{VFOV (mrad)}= \left| \theta_\text{top} - \theta_\text{bottom} \right| \times \frac{\pi }{180} \times 1000

The maximum field of view (MaxFOV) is measured by the user aligning the horizontal line of the center of the pinhole with the top left border of the image. \theta_\text{top left} . Then the user must align the horizontal line of the center of the pinhole with the bottom right border of the image. \theta_\text{bottom right} . Calculations are done by the formula below.

\textbf{MaxFOV (mrad)}= \left| \theta_\text{top left} - \theta_\text{bottom right} \right| \times \frac{\pi }{180} \times 1000