Six-pack holographic imaging for dynamic rejection of out-of-focus objects

Six-pack holography may be used to reject out-of-focus objects in dynamic samples. By illuminating the sample from six different angles in parallel, out-of-focus objects are laterally shifted in six different directions when projected onto the focal plane. Pixel-wise averaging of the six reconstructed images then reduces the impact of out-of-focus objects. The averaged images reduce the contribution of out-of-focus objects by up to 83%, depending on the out-of-focus object axial distance from the focused plane. Simulation results are shown, as well as experimental results for swimming microalgae and flowing microbeads, including numerical refocusing by Fresnel propagation.