The angular extent that can be imaged by the payload. It can be measured in the along-track or across-track directions.

$\vec{\Phi} = 2\arctan{\left( \frac{\vec{s}}{2f} \right)}$

Where:

• $\vec{\Phi} = \begin{bmatrix} \Phi_x \\ \Phi_y \end{bmatrix}$ [°]: Fields of view in the across and along track directions.
• $\vec{s} = \begin{bmatrix} s_x \\ s_y \end{bmatrix}$ [m]: Slit dimensions in the across and along track directions.
• $f$ [m]: Focal length of the foreoptic.

Understanding Focal Length and Field of View | Edmund Optics