rayoptics.oprops.doe module

Module for diffractive/holographic optical elements

Classes that implement diffractive optics capabilities must implement the function phase() for use by the ray trace engine.

The DiffractiveElement and HolographicElement implementations are patterned after Wang, et al, Ray tracing and wave aberration calculation for diffractive optical elements

radial_phase_fct(pt, coefficients)[source]

Evaluate the phase and slopes at pt

Parameters:

pt – 3d point of incidence in Interface coordinates
coefficients – list of even power radial phase coefficients, e.g. r**2, r**4, …

Returns:

(dW, dWdX, dWdY)

dW: phase added by diffractive interaction
dWdX: slope in x direction
dWdY: slope in y direction

class DiffractionGrating(label='', order=1, grating_normal=None, grating_freq_um=1.0, grating_lpmm=None, interact_mode='transmit')[source]

Bases: object

Linear (ruled) diffraction grating.

The phase calculation is patterned after Ludwig, Generalized grating ray-tracing equations.

grating_normal: grating generation surface normal (G)

grating_lpmm: the grating frequency in lines/mm

grating_freq_um: grating frequency in lines per micrometer

order: integer diffraction order used in phase calculation

interact_mode: ‘transmit’|’reflect’

label: string description

property grating_lpmm: the grating spacing in lines/mm.

property grating_freq_um

listobj_str()[source]

phase(pt, in_dir, srf_nrml, ifc_cntxt)[source]

phase_ludwig(pt, in_dir, srf_nrml, ifc_cntxt)[source]

phase_welford(pt, in_dir, srf_nrml, ifc_cntxt)[source]

class DiffractiveElement(label='', coefficients=None, ref_wl=550.0, order=1, phase_fct=None)[source]

Bases: object

Container class for a phase fct driven diffractive optical element

phase_fct: fct the takes an input pt and returns phase and slope

coefficients: list of coeficients for phase function

ref_wl: wavelength in nm for phase measurement

order: which diffracted order to calculate the phase for

label: optical labeling for listing

listobj_str()[source]

phase(pt, in_dir, srf_nrml, ifc_cntxt)[source]

Returns a diffracted ray and phase increment.

Parameters:

pt – point of incidence in Interface coordinates
in_dir – incoming direction cosine of incident ray
srf_nrml – Interface surface normal at pt
z_dir – -1 if after an odd # of reflections, +1 otherwise
wl – wavelength in nm for ray, defaults to ref_wl
n_in – refractive index preceding the interface
n_out – refractive index following the interface

Returns:

(out_dir, dW)

out_dir: direction cosine of the out going ray
dW: phase added by diffractive interaction

class HolographicElement(label='')[source]

Bases: object

Two point hologram element.

listobj_str()[source]

phase(pt, in_dir, srf_nrml, ifc_cntxt)[source]