sagitta

lenstest.lenstest.sagitta(RoC, conic, X, Y, A1=0)

Calculate sagitta for conic surface at points X,Y.

This assumes that the point source of light is located at the center of the mirror madius of curvature, RoC.

The Ronchi grating is located at RoC + z_offset and oriented so lines are perpendicular to the x-axis

The conic section is specified by conic:

conic = ∞ for surface that is flat, conic > 0 for surface that is an oblate spheroid, conic = 0 for surface that is a sphere, 0<conic<-1 for surface that is a prolate spheroid, conic = -1 for surface that is a paraboloid conic < -1 for surface that is a hyperboloid

Parameters:

• RoC – radius of curvature of mirror [mm]

• lines_per_mm – line pairs per mm [1/mm]

• offset – axial offset of grating from center of mirror’s RoC [mm]

• conic – conic constant or Schwartzchild constant [-]

• X,Y – grid of points to evaluate

Returns:

array of points blocked by knife edge