sc506 psf&mtf of doublet lens

8/9/2019 Sc506 PSF&MTF of Doublet Lens

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Calculation of PSF and MTF of DoubletLens

Author: Hartwig Crailsheim (LightTrans)

Related Application Scenarios: 505

Requirements: VirtualLab 5.10.0 Starter Toolbox

License: CC-BY-SA 3.0

Scenario 506 (2.3)
http://www.lighttrans.com/documents_search.html?tx_abdownloads_pi1[sword]=505&no_cache=1http://creativecommons.org/licenses/by-sa/3.0/http://creativecommons.org/licenses/by-sa/3.0/http://www.lighttrans.com/documents_search.html?tx_abdownloads_pi1[sword]=505&no_cache=1


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Modeling Task

This example shows the analysis of a focusing lenssystem and the calculation of the Point SpreadFunction (PSF) and the Modulation TransferFunction (MTF) in VirtualLab.


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Modeling Task

Doublet Lens Focal planePlane Wavewith 532 nm

45 mm

Focusing

Effective Focal Length f=7.83 mm

Calculation of PSF & MTF ofDouble Lens System for Focusing of Collimated Light


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Point Spread Function

VirtualLab does not contain a special functionfor the calculation of the PSF.

The PSF is automatically simulated in Field

Tracing mode if a plane wave or spherical wavelight source will be used. Just replace any realsource temporary by a spherical wave or planewave source.

The PSF is the resulting field in the focal plane ofthe lens system.


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Simulation of PSF


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Modulation Transfer Function

The so called Modulation Transfer Function (MTF)shows what is the maximum spatial frequency thatan incoherent imaging system is able to resolve.

So the MTF demonstrates the transmission ofdifferent spatial frequencies. I.e. it allows someconclusion about possible contrast values.


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MTF Calculation

The MTF corresponds to the Fourier transform ofthe power density of the PSF.

In general the field in the focal plane containsvalues for the x-, y- and z-component.

So in the following the summed squaredamplitudes of Ex, Eyand Eywill be used which areproportional to the power density.

Calculation of MTF:

22 2

PSF, PSF, PSF,MTF

x y znormed

FT E E E = + +


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MTF Detector (Programmable)

For the MTF evaluation theaccording programmabledetector from the detectorcatalog is used to:

1. Sum up the squaredamplitudes of Ex, Ey, Ez.

2. Do a Fourier Transform.

3. Normalize.

4. Take the modulus anddisplay the MTF.


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Light Path Diagram (LPD)


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Simulation Results (Focusing Lens System)

Phase aberrationsafter doublet lens

Point SpreadFunction (PSF) infalse colors


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MTF in 2D

2DMTF(especially of interestfor non rotational

symmetric systems)


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Profile of MTF

Use EditConversionCreateHarmonic Field fromDatato generate an

harmonic field. The MTF data will be

in the real part of theharmonic field after

the conversion. Use the profile line to

show a 1D profile ofthe MTF.


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sc506 psf&mtf of doublet lens

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