MieHolo

MieHolo offers some matlab functions to generate and fit holograms that produced by a single sphere under plane incident light.

System Requirements

• Matlab R2013b or newer, earlier versions should also work but not tested.
• Optimization Toolbox.
• Image Processing Toolbox.

Image Pocessing Toolbox dependency may be removed by replacing fspecial function in radialcenter.m with a predefined image filter. And replace imshow function in example gen_holo.m with image function.

Usage

First add fit/ and mie/ folder to your matlab path.

Typically there are 3 functions to be used:

• mie_holo
• fit1d
• fit2d

Example codes can be found in example/ folder.

Generate holograms

mie_holo is used to generate holograms. You should first generate a meshgrid to define a image plane. See the example below. v and h are vertical and horizonal coordinates relative to the origin of the image plane.

To generate a 201*201 hologram with pixel size 0.2um, and a silica sphere (n=1.456, radius=1) located at 30um above the focal plane in water:

np = 1.456;
ns = 1.33;
wavelen = 0.66;
radius = 1;
pixsize = 0.2;
v_range = linspace(0, 200*pixsize, 201); %grid origin is in upper left conner
h_range = linspace(0, 200*pixsize, 201); %point values are in actual unit
v = 20;
h = 20;
z = 30;
[h_grid, v_grid] = meshgrid(h_range, v_range);
holo = mie_holo(np,ns,wavelen,radius,v_grid,h_grid,v,h,z);
imshow(holo,[]);

You can pass additional parameters to mie_holo to change incident light properties, see mie/mie_holo.m for more details.

Fit holograms

'fit1d' and 'fit2d' are used to fit experimental holograms to mie solutions to extract characteristics of a sphere.

To use these functions, you need to run the configuration code to set parameters. Copy config_sample.m and edit parameters in the copied file, then pass hologram and parameters to the function.

See example/fit_holo.m

References

1. Lee. Characterizing and tracking single colloidal particles with video holographic microscopy Opt. Express, OSA, 2007.
2. Bohren & Huffman. Absorption and Scattering by a Sphere Absorption and Scattering of Light by Small Particles.

License

This code is licensed under GNU GPL V2 license.