GeometricPSF

R2026b

Geometric point spread function result

Since R2026b

Description

Add-On Required: This feature requires the Optical Design and Simulation Library for Image Processing Toolbox add-on.

A GeometricPSF object stores a geometric point spread function (PSF) result for one field point in an optical system. A geometric PSF is computed from ray intersections in the image plane. Use a geometric PSF for fast ray-based image quality analysis when aberrations are large compared to diffraction-limited performance.

Creation

Create a GeometricPSF object by using the psf object function of an opticalSystem object. To return a GeometricPSF object, specify the Method name-value argument as "Geometric", or omit the Method argument.

Properties

Image — PSF intensity image

Read-only: M-by-N-by-K numeric array

This property is read-only.

PSF intensity image, represented as an M-by-N -by-K numeric array. M is the number of image rows, N is the number of image columns, and K is the number of wavelengths specified when computing the PSF.

Data Types: double

FieldPoint — Field point for PSF computation

Read-only: FieldAngle object | FieldPosition object

This property is read-only.

Field point for which the PSF is computed, represented as a FieldAngle object or a FieldPosition object.

Wavelengths — Wavelengths for PSF computation

Read-only: K-element numeric vector

This property is read-only.

Wavelengths used for PSF computation, represented as a K-element numeric vector. Each element is a wavelength in nanometers.

Data Types: double

ReferenceWavelength — Reference wavelength

Read-only: positive scalar

This property is read-only.

Reference wavelength for centering the PSF image, represented as a positive scalar in nanometers.

Data Types: double

Position — Physical extent of PSF image

Read-only: 1-by-4 numeric vector

This property is read-only.

Physical extent of the PSF image in the image-plane coordinate system, represented as a 1-by-4 numeric vector of the form [x y w h], in millimeters. The image-plane coordinate system is centered at [0 0]. x and y specify the location of the extent relative to this coordinate system, and w and h specify the width and height.

Data Types: double

CenterOnChiefRay — Option to center PSF image on chief ray

Read-only: true or 1 | false or 0

This property is read-only.

Option to center the PSF image on the chief ray hit position of the reference wavelength, represented as a logical 1 (true) or 0 (false).

Data Types: logical

Object Functions

centroid	Compute centroid of point spread function
ellipticity	Compute ellipticity of point spread function
encircledEnergyAtRadius	Compute encircled energy of point spread function
radiusAtEncircledEnergy	Compute radius at encircled PSF energy
show	Plot analysis result
showEncircledEnergy	Plot encircled energy of point spread function

Examples

Create Geometric PSF Object

Load the sample Double Gauss lens system using zmximport. Define a field point at an angle of 4 degrees along the x-axis and specify a wavelength of 587.56 nm.

opsys = zmximport("DoubleGaussLens.zmx");
fp = fieldPoint(Angles=[4 0]);
lambda = 587.56;

Compute the geometric PSF for the specified field point and wavelength.

psfr = psf(opsys, FieldPoints=fp, Wavelengths=lambda, Method="Geometric");
psfr

psfr = 
  GeometricPSF with properties:

                  Image: [128×128 double]
             FieldPoint: [1×1 optics.fieldpoint.FieldAngle]
            Wavelengths: 587.5600
    ReferenceWavelength: 587.5600
               Position: [-0.0207 3.8581 0.0415 0.0415]
       CenterOnChiefRay: 1

Compute Metrics from Geometric PSF

Load the sample Double Gauss lens system using zmximport. Define a field point at an angle of 4 degrees along the x-axis, set the wavelength to 587.56 nm, and calculate the geometric PSF.

opsys = zmximport("DoubleGaussLens.zmx");
fp = fieldPoint(Angles=[4 0]);
lambda = 587.56;
psfr = psf(opsys, FieldPoints=fp, Wavelengths=lambda, Method="Geometric");

Use the PSF result object, psfr, to extract spot shape metrics and energy distribution properties. Calculate the centroid position, the structural ellipticity, the fraction of energy contained within a radius of 0.01 units, and the radial boundary that contains 80% of the total energy.

centroidLocation = centroid(psfr);
epsilon = ellipticity(psfr);
energyAtRadius = encircledEnergyAtRadius(psfr, 0.01);
radius80 = radiusAtEncircledEnergy(psfr, 0.8);

More About

Geometric PSF

A Geometric PSF is a ray-based approximation of the point spread function. The psf object function traces rays through the optical system and bins the ray intersections in the image plane to form the intensity image.

Because a GeometricPSF object represents a ray-based PSF, it does not provide the strehlRatio object function. To compute a Strehl ratio, compute a Huygens PSF by specifying Method="Huygens" when you call psf.

Version History

Introduced in R2026b