Sculpting Axial Characteristics of Incoherent Imagers by Hybridization Methods

Abstract

Axial resolving power (ARP) is one of the cornerstones of imaging systems. In conventional imaging systems, changing ARP by changing the numerical aperture affects also lateral resolving power (LRP). It is highly desirable to change ARP independent of LRP. Recently, incoherent digital holography (IDH) techniques were developed using sparse ensembles of Bessel, Airy and self-rotating beams that allow tuning ARP independent of LRP. In the above studies, the ARP was tuned by controlling the randomness which resulted in noisy reconstructions. In this study, we proposed and demonstrated two INCoherent Hybrid Imaging Systems (INCHIS) using a Bessel and spherical beam to change the ARP between the limits of Bessel and spherical beam independent of LRP. The first hybridization technique INCHIS-H1 requires pre-engineering of multifunctional phase masks using a recently developed modified Gerchberg-Saxton algorithm and an active device such as a spatial light modulator. The second hybridization technique INCHIS-H2 can be implemented using both active as well as passive optical elements with lens and axicon functions and the ARP is changed digitally after optical recording. While INCHIS-H1 requires pre-engineering of phase masks to change ARP like any conventional imaging system, the capability in INCHIS-H2 to change ARP post-recording opens a new pathway in imaging technology. Simulation results and proof-of-concept experimental results are presented. A recently developed Lucy-Richardson-Rosen algorithm has been used for image reconstruction for the above cases. We believe that the developed hybridization methods will revolutionize the field of IDH, computational imaging, computer vision and microscopy.

Keywords: Incoherent imaging, digital holography, Computational imaging, diffractive optics, Fresnel incoherent correlation holography, coded aperture imaging