Stability parameter is a value showing if a system can support stable laser operation. It can be calculated in two ways:
P = (A + D) / 2
P = 1 — ((A + D) / 2) 2
where A and D are system round-trip matrix components. In the first case the system is stable when the parameter value is in range from -1 to 1. In the second case the system is stable when the parameter value is in the range from 0 to 1.
rezonator supposes a beam is propagating from left to right in the schema. For single-pass schema, it is as if a light source would be located just before the leftmost element of the schema and is directed to the right side.
When the round-trip matrix is calculated, elements’ matrices are multiplied starting from some reference element and in the direction opposite to beam propagation, as the ray-matrix approach supposes.
Ray vector represents a geometric beam approximation when a beam described by two parameters - a distance from the optical axis r and an angle between the beam and the optical axis V.
When a beam traverses an optical system, parameters of the output beam can be expresses from parameters of the input beam and system’s ray matrix M = [A, B; C, D].
Tangential Plane, T-plane
The tangential plane is the plane containing all the resonator’s elements (the plane of an optical stand). Beams are refracted or reflected in this plane.
Sagittal Plane, S-plane
The sagittal plane is the plane containing the element’s optical axis and perpendicular to the tangential plane.