LaGuer / Digital-Holography

Let's play with digital holograms

Digital Holography

Let's play with digital holograms

Visualization

Reference textbook:

• Digital holography and wavefront sensing by Ulf Schnars, Claas Falldorf, John Watson, and Werner Jüptner, Springer-verlag Berlin an, (2016). (Read section 3.2)

• Introduction to Modern Digital Holography: With Matlab By Ting-Chung Poon, Jung-Ping Liu, Cambridge University Press (2014)

Digital Hologram

'ulf7.BMP' is an *off-axis* digital hologram created by recording an object at about 1 meter distance with HeNe laser (632.8 nm) and an image sensor with 6.8 µm pixel size. The file was kindly provided by Dr. Ulf Schnars.

1. Reconstruction by Fresnel approximation

This offers fastest way of reconstructing a hologram (only one FFT operation). 'Fresnel_reconstruction.ipynb' contains the algorithm.
Fresnel reconstruction result

2. Reconstruction by Convolution approach

This offeres most flexible way of reconstructing a hologram. It is possible to numerically adjust the zoom value in the reconstruction. Involves 3 FFT operations. 'Convolution_reconstruction.ipynb' contains the algorithm.
Convolution reconstruction result

Convolution reconstruction with suppressed DC term (obtained by using hologram - mean(hologram))