WavelengthFromGratingEquation¶
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class
gwcs.spectroscopy.
WavelengthFromGratingEquation
(groove_density, spectral_order, **kwargs)[source]¶ Bases:
astropy.modeling.Model
Solve the Grating Dispersion Law for the wavelength.
Note
This form of the equation can be used for paraxial (small angle approximation) as well as oblique incident angles. With paraxial systems the inputs are
sin
of the angles and it transforms to\((\sin(alpha_in) + \sin(alpha_out)) / (groove_density * spectral_order)\).
With oblique angles the inputs are the direction cosines of the angles.
Parameters: groove_density : int
Grating ruling density in units of 1/length.
spectral_order : int
Spectral order.
Examples
>>> from astropy.modeling.models import math >>> model = WavelengthFromGratingEquation(groove_density=20000*1/u.m, spectral_order=-1) >>> alpha_in = (math.Deg2radUfunc() | math.SinUfunc())(.0001 * u.deg) >>> alpha_out = (math.Deg2radUfunc() | math.SinUfunc())(.0001 * u.deg) >>> lam = model(alpha_in, alpha_out) >>> print(lam) -1.7453292519934437e-10 m
Attributes Summary
groove_density
Grating ruling density in units of 1/m. linear
n_inputs
n_outputs
param_names
return_units
This property is used to indicate what units or sets of units the output of evaluate should be in, and returns a dictionary mapping outputs to units (or None
if any units are accepted).spectral_order
Spectral order. Methods Summary
__call__
(*inputs[, model_set_axis, …])Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated. evaluate
(alpha_in, alpha_out, …)Evaluate the model on some input variables. Attributes Documentation
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groove_density
= Parameter('groove_density', value=1.0)¶ Grating ruling density in units of 1/m.
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linear
= False¶
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n_inputs
= 2¶
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n_outputs
= 1¶
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param_names
= ('groove_density', 'spectral_order')¶
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return_units
¶ This property is used to indicate what units or sets of units the output of evaluate should be in, and returns a dictionary mapping outputs to units (or
None
if any units are accepted).Model sub-classes can also use function annotations in evaluate to indicate valid output units, in which case this property should not be overridden since it will return the return units based on the annotations.
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spectral_order
= Parameter('spectral_order', value=1.0)¶ Spectral order.
Methods Documentation
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__call__
(*inputs, model_set_axis=None, with_bounding_box=False, fill_value=nan, equivalencies=None, inputs_map=None, **new_inputs)¶ Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated.
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