Adaptation of the Standard Off-Axis Digital Holographic Microscope to Achieve Variable Magnification

Abstract

Traditional microscopy provides only for a small set of magnifications using a finite set of microscope objectives. Here, a novel architecture is proposed for quantitative phase microscopy that requires only a simple adaptation of the traditional off-axis digital holographic microscope. The architecture has the key advantage of continuously variable magnification, resolution, and Field-of-View, by simply moving the sample. The method is based on combining the principles of traditional off-axis digital holographic microscopy and Gabor microscopy, which uses a diverging spherical wavefield for magnification. We present a proof-of-concept implementation and ray-tracing is used to model the magnification, Numerical Aperture, and Field-of-View as a function of sample position. Experimental results are presented using a micro-lens array and shortcomings of the method are highlighted for future work; in particular, the problem of aberration is highlighted, which results from imaging far from the focal plane of the infinity corrected microscope objective.

Keywords

• digital holographic microscopy
• digital inline holographic microscopy
• variable magnification
• off-axis holography