Evaluation of spatial-spectral filtering in non-paraxial volume holographic imaging systems

Abstract

In this thesis, the properties of transmission-mode volume phase holograms as spatial-spectral filters in optical systems for microscopic medical imaging are evaluated. In experiment, the relationship between the angle of incidence and diffraction efficiency are invesitgated for wavelength-detuned multiplex holograms to establish the limits of the narrow bandwidth lateral field of view. The depth selectivity of the microscope with a volume hologram pupil is also measured and found to vary significantly with recording parameters and lateral shift of the probe point source in object space. This experiment is modified to incorporate controlled levels of spherical aberration, where the effect on the depth selectivity is evaluated. A novel resolution target designed specifically for the evaluation of this imaging system is described and imaged. A flexible approach based on the 1st-order Born approximation is implemented to simulate all aspects of the imaging system with a multiplex volume hologram pupil. The simulation is then used to verify and expand upon the experimental results. A mathematical treatment of the nature of the anomalous apparent curvature of the diffraction image is performed, showing that a volume grating recorded in plane has weak out-of-plane spatial filtering behavior.