Biophotonics Laboratory
California Institute of Technology


Fourier Ptychographic Microscopy (FPM)
ePetri Dish Project
Optofluidic Microscopy (OFM)
Wide Field of View Microscopy (WFOV)
Turbidity Suppression by Optical Phase Conjugation in Biological Media
Coherence Domain Probing Systems


Differential interference contrast (DIC) microscopy based on Young’s interference

Differential interference contrast (DIC) microscopy has been very successful in rendering excellent phase contrast for transparent specimens, and is widely used in biology and clinical laboratories. We are developing a novel DIC microscope based on Young’s interference, mimicking Young’s original two-slit interference setup. It does not require any complicated or expensive optical components, and as such it is less expensive and more robust than the conventional DIC microscope. In addition, commercially available DIC microscopes have limitations in imaging the samples that have anisotropic refractive index distribution such as bones and teeth. DIC microscopes interfere orthogonally polarized beams to produce phase contrast. As a result, any change in the linear polarization caused by the optical anisotropy of the sample can render an incorrect phase relationship. However our DIC setup will not suffer from this because our reference and sample beams have the same polarization. Another promising feature of the technique is that its simplicity implies that we can easily integrate it on a chip to implement an on-chip DIC microscope.

Figure 1. The principle of Differential interference contrast (DIC) microscopy based on Young’s interference


Figure 2. (a) Device geometry and principle of operation. (b) SEM image and (c) interference pattern of 600 nm holes with 600 nm spacing. (d), (e) Same plots for holes with 1.2 μm spacing. (f), (g) Same plots for holes with 2.4 μm spacing.

Figure 3. (a) Intensity, (b) u component and (c) v component of differential phase, and (d) vector representation of differential phase of a Gaussian beam. (e)–(h) Same plots for an optical vortex.


M. Lew, X. Q. Cui, X. Heng, and C. H. Yang, "Interference of a four-hole aperture for on-chip quantitative two-dimensional differential phase imaging," Optics Letters 32, 2963-2965 (2007). (pdf)