This paper introduces a new portable platelet aggregation instrument based on optical transmittance measurement. The platelet-rich plasma is aggregated after adding trapping agent and leads to a transmittance enhancement. By analyzing the transmittance evolution curve, the platelet aggregation function can be obtained, which is helpful for doctors to do clinical diagnosis of thrombotic disease and make a prescription of drugs. The design of the optical module, the signal processing circuit, and the software are described in detail. After assembling the instrument, several tests of blood samples are carried out to verify its performance. The instrument is compact and easy to use, so it is potential for rapid detection or real-time monitoring.
This paper introduces a compact data acquisition for micro spectrometer. The system uses a linear CMOS sensor to capture the spectrum, and a single STM32 ARM chip to control, to process and to transfer the signals. Compared with the traditional data acquisition system based on FPGA and ARM chips, this system has smaller size and lower cost, making it suitable for use in micro spectrometer. The performance of the system is also evaluated by a series of experiments. The system shows good linearity and accuracy. The responses under different integration time, different pixel, and different wavelength are also measured, which is important for signal correction in spectrum measurement.
In this work we design a wire grid polarizer(WGP) with silver nanowire grids on a germanium(Ge) substrate with 550nm period and 200nm thickness double-layer and single-layer wire grids based on FDTD method, which can achieve an average TM transmittance(TMT) over 70% and 48% and an extinction ratio(ER) over 76dB and 32dB respectively in the range of 3~15μm waveband. The photoresist grating was made by the Lloyd’s mirror interferometer interference lithography (IL) systems and the metal silver was deposited by thermal evaporation, which avoid the high cost of electron beam lithography and the difficult process of wet etching or dry etching. The fabrication shows that method is proved to be easy implement in the fabrication of sub-wavelength metal gratings. The experiment results show the polarizer has uniform polarization characteristics in the wide infrared band that the average TMT and ER of the doublelayer polarizer are 72.6% and 27.5dB in 3~15μm with single side antireflection coating. The average TMT and ER of the single-layer polarizer are 59.1% and 25.1dB in 3~15μm.
A new type of plane optical lens, the Fresnel-grating lens with variable-line-space grating surface based on dual pointsource holographic technique, is demonstrated, optimized and fabricated in this research. The Fresnel-grating lens integrates the function of a diffraction grating and a Fresnel lens, and provides collimation, focusing as well as dispersion effects at the same time, which simplifies the optical structure and fits perfectly for a miniature spectrometer. The variable-line-space grating surface can enhance the modulation ability of the spectrometer system A mathematical model is established based on the least wave-change principle and the system parameters are optimized using optics simulation software ZEMAX. The fabrication procedures for the Fresnel-grating lens with soft lithography are illustrated in detail, and a dual-point holographic exposure optical path to form the grating surface as well as a mold to cast the Fresnel-grating lens are constructed. Samples of Fresnel-grating lens with the size of 16mm×16mm×5mm are fabricated and preliminarily tested. The period on the central part of fabricated grating surface is 926±2nm and the results show great consistency with the simulation. With further testing in the spectrometer system, the Fresnel-grating lens with a variable-line-space grating surface holds considerable potential in the miniature spectrometer area.
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