Digital micromirror device-based laser-illumination Fourier ptychographic microscopy

• Published in: Optics express Vol. 23; no. 21; pp. 26999 - 27010
• Main Authors: Kuang, Cuifang, Ma, Ye, Zhou, Renjie, Lee, Justin, Barbastathis, George, Dasari, Ramachandra R, Yaqoob, Zahid, So, Peter T C
• Format: Journal Article
• Language: English
• Published: United States Optical Society of America 19.10.2015
• Subjects: Equipment Design; Equipment Failure Analysis; Fourier Analysis; Image Enhancement - instrumentation; Lasers; Lenses; Lighting - instrumentation; Microscopy - instrumentation; Miniaturization; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted - instrumentation
• DOI: 10.1364/OE.23.026999
• ISSN: 1094-4087

We report a novel approach to Fourier ptychographic microscopy (FPM) by using a digital micromirror device (DMD) and a coherent laser source (532 nm) for generating spatially modulated sample illumination. Previously demonstrated FPM systems are all based on partially-coherent illumination, which offers limited throughput due to insufficient brightness. Our FPM employs a high power coherent laser source to enable shot-noise limited high-speed imaging. For the first time, a digital micromirror device (DMD), imaged onto the back focal plane of the illumination objective, is used to generate spatially modulated sample illumination field for ptychography. By coding the on/off states of the micromirrors, the illumination plane wave angle can be varied at speeds more than 4 kHz. A set of intensity images, resulting from different oblique illuminations, are used to numerically reconstruct one high-resolution image without obvious laser speckle. Experiments were conducted using a USAF resolution target and a fiber sample, demonstrating high-resolution imaging capability of our system. We envision that our approach, if combined with a coded-aperture compressive-sensing algorithm, will further improve the imaging speed in DMD-based FPM systems.