We have fabricated a simple and compact scanning laser optical system using microelectromechanical system (MEMS) scanner that can be incorporated into portable health monitoring devices. The two-dimensional (2-D) MEMS scanner used in this system is much smaller and light in weight compared to galvanometer scanners and polygon scanners used in the commercially available ophthalmic devices. MEMS scanners have many advantages and also limitations compared to galvanometer and polygon scanners. An easy to use and compact device is more useful for rapid alignment for measurement and data acquisition. Sensitivity of the system was quantified by measuring signal-to-noise ratio (SNR) for both high and low reflectivity materials. SNR was 10 for the high reflectance materials and about 4 for low reflectance materials, which is sufficient for biological imaging. Distortion generated using large scanning angle of 2-D MEMS scanner was corrected in real time by custom made LabVIEW program. Ocular safety is important to consider when using a laser for ophthalmic devices. We calculated the maximum permissible beam power for thermal damage and photochemical damage considering the specification of our system such as visual angle and wavelength of the laser beam. The measured laser intensity in the front of model eye was 6 μW, which is much smaller than the maximum permissible beam power recommended by the American National Standards Institute.
We propose, design and fabricate here an electrostatically actuated continuous single-crystal-silicon membrane deformable mirror (DM) for astronomical observation. To get a large stroke, a bimorph spring array is used to generate a large air gap between the mirror membrane and the electrode. A DM with a 1.8mm×1.8mm mirror membrane are fabricated by combining Au-Si eutectic wafer bonding and the subsequent all-dry release process. The stroke of the DM is 3.5μm at 115V. The influence function on the nearest neighbor is 51%. The fill factor of the DM is 99.9%.
The surface grating technologies enable to control the thermal radiation spectrum. We are applying this
technique to promote the chemical reaction to produce hydrogen in the methane steam reforming process by
spectrally resonant thermal radiation. The thermal radiation spectrum is adjusted to vibrational absorption
bands of methane and water molecules near 3 μm by making a two-dimensional surface grating of period
Λ=2.6 μm on the radiative surface. By matching the peak of thermal radiation to the absorption bands of
gases, it is clearly observed that the hydrogen production is promoted five times as much as the case without
spectrally resonant thermal radiation by the optical excitation of vibrational energy levels of molecules.
From a series of experiments and analysis, it is suggested that radiative gas effectively excited the molecules
up of high energy vibrational and rotational levels, and this lead to the high production rate of hydrogen in
methane steam reforming process.