SCATMECH > Classes and Functions > Surface Scattering Models > Finite_Aperture_Instrument_BRDF_Model

class Finite_Aperture_Instrument_BRDF_Model

The class Finite_Aperture_Instrument_BRDF_Model calculates the light scattering averaged over a solid angle given by a circular detector with uniform sensitivity. It accepts as a parameter another BRDF_Model and a half angle for the detector. Integration is performed over a circular aperture using a multi-point integration scheme based upon Gauss-Zernike integration.

Diagram illustrating the Finite_Aperture_Instrument_BRDF_Model.

Parameters:

Parameter Data Type Description Default
lambda double Wavelength of the light in vacuum [µm].
(Inherited from BRDF_Model.)		 0.532
type int Indicates whether the light is incident from above the substrate or from within the substrate and whether the scattering is evaluated in reflection or transmission. The choices are:
0 : Light is incident from the above the substrate, and scattering is evaluated in reflection.
1 : Light is incident from the above the substrate, and scattering is evaluated in transmission.
2 : Light is incident from the within the substrate, and scattering is evaluated in reflection.
3 : Light is incident from the within the substrate, and scattering is evaluated in transmission.
For 1, 2, and 3, the substrate must be non-absorbing.
Finite_Aperture_Instrument_BRDF_Model supports all modes supported by parameter model.
(Inherited from BRDF_Model).		 0
substrate dielectric_function The optical constants of the substrate, expressed as a complex number (n,k) or, optionally, as a function of wavelength.
(Inherited from BRDF_Model.)		 (4.05,0.05)
alpha double The half angle of the circular aperture over which the scattering is averaged [deg]. 0
integralmode int The integration order, ranging from 1 to 7. The number of points in the integration depends upon this order and are 1, 4, 7, 16, 21, 36, and 43 for orders 1, 2, 3, 4, 5, 6, and 7, respectively. 3
model BRDF_Model_Ptr The light scattering model.
Note: The parameters lambda, type, and substrate must match those of model.		 Microroughness_BRDF_Model

See also:

SCATMECH Home,   Conventions,   Instrument_BRDF_Model,   dielectric_stack

NIST Digital Library of Mathematical Functions, Section 3.5(x), Numerical Methods, Quadrature, Cubature Formulas.

T.A. Germer and H.J. Patrick, "Effect of bandwidth and numerical aperture in optical scatterometry," Proc. SPIE 7638, 76381-F (2010).

Include file:

#include "finiteaperture.h"

Source code:

finiteaperture.cpp

Definition of public elements:

class Finite_Aperture_Instrument_BRDF_Model
  : public Instrument_BRDF_Model
{
};

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Current SCATMECH version: 7.22 (April 2021)