Polygon-based computer-generated holography: a review of fundamentals and recent progress [Invited].

In this review paper, we first provide comprehensive tutorials on two classical methods of polygon-based computer-generated holography: the traditional method (also called the fast-Fourier-transform-based method) and the analytical method. Indeed, other modern polygon-based methods build on the idea of the two methods. We will then present some selective methods with recent developments and progress and compare their computational reconstructions in terms of calculation speed and image quality, among other things. Finally, we discuss and propose a fast analytical method called the fast 3D affine transformation method, and based on the method, we present a numerical reconstruction of a computer-generated hologram (CGH) of a 3D surface consisting of 49,272 processed polygons of the face of a real person without the use of graphic processing units; to the best of our knowledge, this represents a state-of-the-art numerical result in polygon-based computed-generated holography. Finally, we also show optical reconstructions of such a CGH and another CGH of the Stanford bunny of 59,996 polygons with 31,724 processed polygons after back-face culling. We hope that this paper will bring out some of the essence of polygon-based computer-generated holography and provide some insights for future research.

[Micro-Raman and fluorescence spectra of several agrochemicals].

Raman and fluorescence spectra from several agrochemicals were measured, which are sold for the use in vegetables, fruits and grains. Characteristic vibration Raman peaks from some of the agrochemicals were recorded, hence the spectra can be used for their identification. Other marketed agrochemicals demonstrated strong fluorescence under 514.5 nm excitation. It was found that the fluorescence spectra of the agrochemicals are very different. According to these results one can detect the trace amount of agrochemicals left on the surface of fruits, vegetables and grains in situ and conveniently.

[Studies of penicillins by micro Raman spectroscopy].

The Raman spectra of three kinds of penicillins were obtained and investigated by micro Raman technique. By comparing these Raman spectra, we find there are many differences among them, and it can be used as an important criterion in distinguishing different kinds of penicillins. In this paper, the characteristic Raman peaks of penicillins have been given. In other hand, we find there is no much difference in the Raman spectra of same kind of penicillin, even though different plants produce them. So, the Raman spectra can't be used to make sure whether certain plant produces one sample.