JWST POPPY:docs

BandLimitedCoron

class poppy.BandLimitedCoron(name='unnamed BLC', kind='circular', sigma=1, wavelength=None, **kwargs)[source] [edit on github]

Bases: poppy.poppy_core.AnalyticOpticalElement

Defines an ideal band limited coronagraph occulting mask.

Parameters :

name : string

Descriptive name

kind : string

Either ‘circular’ or ‘linear’. The linear ones are custom shaped to NIRCAM’s design with flat bits on either side of the linear tapered bit. Also includes options ‘nircamcircular’ and ‘nircamwedge’ specialized for the JWST NIRCam occulters, including the off-axis ND acq spots and the changing width of the wedge occulter.

sigma : float

The numerical size parameter, as specified in Krist et al. 2009 SPIE

wavelength : float

Wavelength this BLC is optimized for, only for the linear ones.

Methods Summary

getPhasor(wave) Compute the amplitude transmission appropriate for a BLC for some given pixel spacing corresponding to the supplied Wavefront.

Methods Documentation

getPhasor(wave)[source] [edit on github]

Compute the amplitude transmission appropriate for a BLC for some given pixel spacing corresponding to the supplied Wavefront.

Based on the Krist et al. SPIE paper on NIRCam coronagraph design

Note that the equations in Krist et al specify the intensity transmission of the occulter, but what we want to return here is the amplitude transmittance. That is the square root of the intensity, of course, so the equations as implemented here all differ from those written in Krist’s SPIE paper by lacking an exponential factor of 2. Thanks to John Krist for pointing this out.

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