Development of a DMD-based fluorescence microscope

Abstract

We present a versatile fluorescence microscope, built by complementing a conventional fluorescence microscope with a digital micro-mirror device (DMD) in the illumination path. Arbitrary patterns can be created on the DMD and projected onto the sample. This patterned illumination can be used to improve lateral and axial resolution over the resolution of a wide-field microscope, as well as to reduce the illumination dose. Different illumination patterns require different reconstruction strategies and result in an image quality similar to confocal or structured illumination microscopy. We focus on the optical design and characterization of a DMD-based microscope. Estimation of the optical quality of the microscope has been carried out by measuring the modulation transfer function from edge profiles. We have obtained optically sectioned images by applying multi-spot illumination patterns followed by digital pinholing. The sectioning capabilities of our DMD-based microscope were estimated from the dependence of the signal-to-background and signalto-noise ratios on the pitch of the projected multi-spot patterns and the size of the digital pinhole. In addition, we provide an outlook on the use of pseudo-random illumination patterns for achieving both sectioning and resolution enhancement.

Deconvolution methods for structured illumination microscopy

“…Structured illumination is provided by the fast and flexible DMD, and fluorescence from the sample is recorded in a widefield mode by the sCMOS camera (Orca Flash 4.0, Hamamatsu Photonics, Japan). Further technical details about the optical design of the microscope can be found in our earlier work [36]. The following experimental parameters were used for imaging: 60 × ∕0.7 objective, 488/520 nm excitation/emission wavelength, 108 nm camera pixel size, and 137 nm DMD pixel size (back-projected to the sample plane).…”

Digital micromirror based near-infrared illumination system for plasmonic photothermal neuromodulation

“…Several optical configurations have been implemented as light pattern generator to avoid illumination vignette. Expanded collimation [22], diffuser [23] and beam shaper [24] have been used for light homogenization, but severe power loss limits maximum applicable power density. Fly eye lens makes flat illumination by dividing each spatial beam path, but the lens dimension should be customized to guide light pattern into a microscope.…”

DMD-based super-resolution structured illumination microscopy visualizes live cell dynamics at high speed and low cost

“…An important aspect comes into play when using a coherent laser light source. Here, the sawtooth-like surface formed by the tilted mirrors leads to a so-called blazed grating, which superposes the regular SIM interference pattern generated by the pattern displayed by the device, with the underlying microscopic mirror structure [19,20]. Thus, for coherent light, the device can be viewed as phase-modulating, because each point on the tilted mirror surfaces introduces a corresponding phase delay.…”