The history of the study on pterido-flora in Vietnam is reviewed. Two new records, Adiantum capillus-junonis and Actinostachys wagneri are reported for Vietnam based on our new collections. A new species, Hymenophyllum bryoides, is described to accommodate its morphological and genetic distinctiveness from other congeneric species. Photographs of key characters, distributions, ecology, and notes on all the above species are provided.Keywords—Fern, Indochina, new species
A novel scheme involving a three-dimensional (3D) coupling structure is used to build a laser diode (LD) module that utilizes the fiber angle space more completely. Compared with the traditional 2D configuration, the number of LD’s is increased by 4, obtaining an increased efficiency of over 90%. Another advantage is that some costly optical elements used in the traditional polarization combination method are not necessary.
We present a phase-shifting interferometric system that uses the photoelastic modulator (PEM) with the stroboscopic illumination technique. The laser diode is controlled by a programmable pulse generator for triggering four short pulses at their specific temporal phase angles of a modulation cycle for phase-shifting operation. Thereby, the intensity variation of the PEM modulated signal can be freezed and the interferograms captured by a charge-coupled device. In this configuration, no mechanical operations are required in phase-shifting by using the stroboscopic illumination technique, and fast interference fringe measurements are possible. We performed experiments to demonstrate the phase map of two static samples and confirmed that the method is applicable to imaging the complex phase distributions of dynamic objects at speed of 2 Hz. The thickness deviation is almost less than 5% for an ultra-thin transparent film.
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