SetDiffractEfficiencyVolHOE Subroutine

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SetDiffractEfficiencyVolHOE

Description

This subroutine sets the parameters for a volume hologram efficiency specification. Gratings have a primary and secondary efficiency specification that allows an accounting of which side of the grating a ray is incident from. This script command modifies the primary efficiency specification. For more information, refer to the gratings help topic.

Syntax

SetDiffractEfficiencyVolHOE grat, nAve, dN, a, dA, thick, order0, order1, wavl

Parameters

grat As Long

Node number of the surface whose grating efficiency specification is being modified.

nAve As Double

Average refractive index of the emulsion. nAve must obey the following rules:

•nAve >= 0.0

•nAve - dN >= 1.0

dN As Double

Amplitude variation of the refractive index. dN must obey the following rules:

•dN >= 0.0

•dN <= 0.1*nAve

•nAve - dN >= 1.0

a As Double

Absorption coefficient of the material (system units^-1). a must obey the following rules:

•a <= 0.1*(2*PI*nAve/wavel)

dA As Double

Amplitude variation of the absorption coefficient (system units^-1). dA must obey the following rules:

•dA >= 0.0

•dA <= 0.1*(2*PI*nAve/wavel)

•dA <= a

thick As Double

Hologram emulsion thickness (system units). The emulsion thickness must obey the following rules:

•thick >= 0.0

•thick >= 0.1*wavel

order0 As String

Meaning of the 0th diffraction order. Options are:

Value	Meaning
none	No component is propagated along the 0th order direction. Order0 can only be set to none if order1 is also none.
signal	The 0th order contains the response wave of the grating. Order1 can be either none or reference.
reference	The 0th order contains the reference wave of the grating. Order 1 can be either none or signal.

order1 As String

Meaning of the 1st diffraction order. Options are:

Value	Meaning
none	No component is propagated along the 1st order direction. The value of order0 can be set to none, signal, or reference.
signal	The 1st order contains the response wave of the grating. The value of order0 must be set to reference.
reference	The 1st order contains the reference wave of the grating. The value of order0 must be set to signal.

wavl As Double

This parameter is used to check that the parameters of the volume hoe efficiency are valid and lie within the allowed ranges.

Examples

The example below demonstrates how to retrieve the volume hologram efficiency parameters from the primary efficiency table, modify the refractive index amplitude variation and then set the updated parameters back to the primary efficiency table.

Sub main

Dim grat As Long

grat = FindFullName( "Geometry.Elem 1.Surf 2" )

Dim nAve As Double, dN As Double, a As Double, dA As Double, thick As Double

Dim order1 As String, order2 As String

Dim wavl As Double

GetDiffractEfficiencyVolHOE( grat, nAve, dN, a, dA, thick, order1, order2, wavl )

Print "Grating settings:"

Print "Node: " & Chr(9) & GetFullName( grat )

Print "N avg: " & Chr(9) & nAve

Print "delta N: " & Chr(9) & dN

Print "Absorption: " & Chr(9) & a

Print "delta A: " & Chr(9) & dA

Print "Thickness: " & Chr(9) & thick

Print "Order 1: " & Chr(9) & order1

Print "Order 2: " & Chr(9) & order2

Print "Wavl: " & Chr(9) & wavl

'Change dN

dN = dN + 0.005

SetDiffractEfficiencyVolHOE( grat, nAve, dN, a, dA, thick, order1, order2, wavl )

Update

End Sub