[ Identification | Description | Input parameters | Output parameters | Links ]

# The `Lens` Component

Refractive lens with absorption, incoherent scattering and surface imperfection.

## Identification

- Author: C. Monzat/E. Farhi/S. Desert/G. Euzen
- Origin: ILL/LLB
- Date: 2009
- Version: $Revision 1.0$

## Description

    Refractive Lens with absorption, incoherent scattering and surface imperfection.
    Geometry may be:
      spherical (use r1 and r2 to specify radius of curvature),
      planar (use phiy1 and phiy2 to specify rotation angle of plane w.r.t beam)
      or parabolic (use focus1 and focus2 as optical focal length).
    The lens cross-section is seen as a 2*radius disk from the beam Z axis.
    Usually, you should stack more than one of these to get a significant effect
    on the neutron beam, so-called 'compound refractive lens'.
    The focal length for N lenses with focal 'f' is f/N.

    Common material:
      MgF2: density=3.148,weight=62.3018,sigma_coh=11.74,sigma_inc=0.0816,sigma_abs=0.0822
      diamond: density=3.52,weight=12.01,sigma_coh=5.551,sigma_inc=0.001,sigma_abs=0.0035
      Quartz/silica:density=2.53,weight=60.08,sigma_coh=10.625,sigma_inc=0.0056,sigma_abs=0.1714
      perfluoropolymer

    Example: Lens(r1=0.025,r2=0.025, thickness=0.001,radius=0.0150)

    %BUGS
    parabolic shape is not fully validated yet, but should do still...

WARNING: This is a contributed Component.

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
r1 | m | radius of the first circle describing the lens. r>0 means concave face, r<0 means convex, r=0 means plane | 0
r2 | m | radius of the second circle describing the lens r>0 means concave face, r<0 means convex, r=0 means plane | 0
focus1 | m | focal of the first parabola describing the lens | 0
focus2 | m | focal of the second parabola describing the lens | 0
phiy1 | deg | angle of plane1 (r1=0) around y vertical axis | 0
phiy2 | deg | angle of plane2 (r2=0) around y vertical axis | 0
thickness | m | thickness of the lens between its two surfaces | 0.001
radius | m | radius of the lens section, e.g. beam size | 0.015
sigma_coh | barn | coherent cross section | 11.74
sigma_inc | barn | incoherent cross section | 0.0816
sigma_abs | barn | thermal absorption cross section | 0.0822
density | g/cm3 | density of the material for the lens | 3.148
weight | g/mol | molar mass of the material | 62.3018
p_interact | 1 | MC Probability for scattering the ray; otherwise transmit | 0.1
focus_aw | deg | vertical angle to forward focus after scattering | 10
focus_ah | deg | horizontal angle to forward focus after scattering | 10
RMS | Angs | root mean square roughness of the surface | 0

## Output parameters

Name | Unit | Description | Default
--- | --- | --- | ---
rho |  |  |
bc |  |  |
my_s |  |  |
my_a_v |  |  |
mean_n |  |  |
events |  |  |

## Links

- Source code for `Lens.comp`.

[ Identification | Description | Input parameters | Output parameters | Links ]