ECH_FRSPR

Determine the free spectral range in Angstroms

Description

Determine the central wavelength of the specified order and then use the grating equation directly to calculate the free spectral range.

ECH_INIT must be called before calling this routine.

Invocation

CALLECH_FRSPR (M, THETA, GAMMA, FREE, STATUS)

Arguments
READ M INTEGER

Order number for which to calculate the free spectral range

READ THETA REAL

Echelle theta angle corresponding to the current configuration (radians)

READ GAMMA REAL

Echelle gamma angle corresponding to the current configuration (radians)

WRITE FREE REAL

Free spectral range (Angstroms)

READ, WRITE STATUS INTEGER

Global status value

Bugs

None known.

Authors

C.J. Hirst UCL (ZUVAD::CJH)