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Digital micro-mirror devices (DMDs) have been deployed in many optical applications. As compared to spatial light modulators (SLMs), they are characterized by their much faster refresh rates (full-frame refresh rates up to 32 kHz for binary patterns) compared to 120 Hz for most liquid crystal SLMs. DMDs however can only display binary, unipolar patterns and utilize temporal modulation to represent with excellent accuracy multiple gray-levels in display applications. We used the built-in time domain dynamic range representation of the DMD to project 8-bit complex-fields. With this method, we demonstrated 8-bit complex field modulation with a frame time of 38.4 ms (around 0.15 s for the entire complex-field). We performed phase conjugation by compensating the distortions incurred due to propagation through free-space and a scattering medium. For faster modulation speed, an electro-optic modulator was used in synchronization with the DMD in an amplitude modulation mode to create grayscale patterns with frame rate ~ 833 Hz with display time of only 1.2 ms instead of 38.4 ms for time multiplexing gaining a speed up by a factor of 32. [ABSTRACT FROM AUTHOR]

There is an ongoing technological revolution in the field of biomedical instruments. Consequently, high performance healthcare devices have led to remarkable economic developments in the medical hardware industry. Until now, nearly all optical bio-imaging systems are based on the 2-dimensional imaging chip architecture. In fact, recent developments in digital micromirror devices (DMDs) are gradually making their way from conventional optical projection displays into biomedical instruments. As an ultrahigh-speed spatial light modulator, the DMD may offer a range of new applications including real-time biomedical sensing or imaging, as well as orientation tracking and targeted screening. Given its short history, the use of DMD in biomedical and healthcare instruments has emerged only within the past decade. In this paper, we first provide an overview by summarizing all reported cases found in the literature. We then critically analyze the general pros and cons of using DMD, specifically in terms of response speed, stability, accuracy, repeatability, robustness, and degree of automation, in relation to the performance outcome of the designated instrument. Particularly, we shall focus our discussion on the use of Micro-Electro-Mechanical System (MEMS)-based devices in a set of representative instruments including the surface plasmon resonance biosensor, optical microscopes, Raman spectrometers, ophthalmoscopes, and the micro stereolithographic system. Finally, the prospects of using the DMD approach in biomedical or healthcare systems and possible next generation DMD-based biomedical devices are presented. [ABSTRACT FROM AUTHOR]

A homogeneous one-dimensional optical lattice is demonstrated by using a high-precision beam shaper based on a digital micro-mirror device (DMD) with an imaging system containing a pinhole low-pass filter (LPF). This system is capable of producing a high-quality flattop beam profile to form a standing-wave optical lattice with a 50 x 50 µm² flattop region. The periodic potential generated by the optical lattice confines ultracold atoms in Bose-Einstein condensate experiments. We conducted beam shaping tests at several wavelengths by implementing various coherent and incoherent light sources in the visible and infrared wavelength ranges. Experiments produced flattop and other well-controlled beam profiles with 0.2% to 0.26% root-mean-square (RMS) error after applying a digital LPF and nearly flat phase. Several concerns for the system design are presented. First, the energy requirement was determined by power conversion analysis and DMD diffraction efficiency simulation. In addition, a LabVIEW program was written to accelerate the speed of the iterative process for beam profile refinement. Finally, various camera calibrations improved the measurement accuracy. We achieved a 1.25% RMS error flattop beam with diameter of 70.4 µm at the atoms' plane. Other beam profile measurements in different diagnostic planes demonstrated a good intensity uniformity of the optical lattice. [ABSTRACT FROM AUTHOR]