Yanmeng Jiang

H-PDLC based waveform controllable optical choppers for FDMF microscopy

An electrically waveform controllable optical chopper based on holographic polymer dispersed liquid crystal grating (H-PDLC) is presented in this paper. The theoretical analyses and experimental results show that the proposed optical chopper has following merits: (1) controllable waveform, (2) no mechanical motion induced vibrational noise, and 
(3) multiple-channel integration capability. The application of this unique electrically controllable optical chopper to frequency division multiplexed fluorescent microscopy is also addressed in this paper, which has the potential to increase the channel capacity, the stability and the reliability. This will be beneficial to the parallel detection, especially for dynamic studies of living biological samples.

Experiments and quantitative analysis of frequency division multiplexing confocal fluorescence microscopy with UV excitation

In this paper, we experimentally demonstrated a two‐channel frequency division multiplexing confocal fluorescence microscopy system using a UV laser as the excitation source. In our two‐channel frequency division multiplexing confocal fluorescence system, the incoming laser beam was divided into two beams and each beam was modulated with an individual carrier frequency. These two laser beams were then spatially combined with a small angle and focused into two diffraction‐limited spots on the targeted cell (rat neural cell) surface to generate fluorescent signal. As a result, the fluorescent signals from two spots of the rat neural cell surface can be demodulated and distinguished during data processing. Furthermore, a quantitative analysis on the cross‐talk among different frequencies was provided as well. The experimental results confirm that the two‐channel frequency division multiplexing confocal fluorescence technology can not only maintain the high spatial resolution, but also realize the multiple points detection simultaneously with high temporal resolution (within millisecond level range), which benefits the dynamic studies of living biological cells.

High-frequency H-PDLC optical chopper for frequency division multiplexing fluorescence confocal microscope system

The optical chopper array based on Holographic Polymer Dispersed Liquid Crystal (H-PDLC) working at high frequencies, for example 1KHz, 2KHz, and its application in an improved Frequency Division Multiplexed Fluorescence Confocal Microscope (FDMFCM) system are reported in this article. The system is a combination of the confocal microscopy and the frequency division multiplexing technique. Taking advantages of the optical chopper array based on H-PDLC that avoids mechanical movements, the FDMFCM system is able to obtain better Signal-Noise Ratio (SNR), smaller volume, more independent channels and more efficient scanning. Whats more, the FDMCFM maintained the high special resolution ability and realized faster temporal resolution than pervious system. Using the proposed device, the FDMFCM system conducts successful parallel detection of rat neural cells. Fluorescence intensity signals from two different points on the specimen, which represent concentration of certain kind of proteins in the sample cells, are achieved. The experimental results show that the proposed H-PDLC optical chopper array has feasibility in FDMFCM system, which owes to its unique characteristics such as fast response, simple fabrication and lower consumption etc. With the development of H-PDLC based devices, there will be prospective in upgrading FDMFCM systems performance in the biomedical area.

Experiments of electrically controlled optical choppers based on H-PDLC gratings

An experimental investigation on a novel electrically controlled optical chopper based on holographic polymer dispersed liquid crystal (H-PDLC) gratings is presented in this paper. In order to realize the chopping function, a corresponding electrical driving source and controlling circuit are developed for the phase type H-PDLC grating, so that the H-PDLC chopper can not only modulate a light beam with variable frequencies at different duty ratios but also generate other types of waveform modulation such as the sinusoidal modulation to replace the traditional rectangular modulation. Experimental results on one-channel, two-channel and four-channel H-PDLC optical choppers showed that, in comparison with the mechanical chopper counterpart, this device had the advantages of (1) lower noise without mechanical moving part, (2) higher conveniences in terms of changing its operational frequencies, duty ratios and modulation curves, and (3) multi-channel modulation capability. Therefore, it will have a great potential for applications that requires frequency modulations such as frequency modulated confocal microscopy system.

Electrically controlled H-PDLC array modulated multi-frequencies division multiplexed fluorescence confocal microscopy

A novel two channel multi-frequencies division multiplexed confocal fluorescence microscopy (FDMCF) system based on the holographic polymer dispersed liquid crystal (H-PDLC) optical chopper modulation is reported. The characteristic of unique FDMCF system is that within the FDMCF system, the multi-channel exciter laser beams are modulated with different carrying frequencies, after the fluorescence signals are collected, and through data analyzing process, the FDMCF system can realize the multiply points parallel detection synchronously with high temporal and spatial resolution. Besides, combined with the electrically controlled H-PDLC grating array working as the optical chopper to replace the mechanical chopper, it can improve and develop the FDMCF system from two channels to unlimited system. The paper has done the experiments to demonstrate the two-channel FDMCF system based on H-PDLC modulation and analysis the benefits from the electrically-controlled integrated electro-optical H-PDLC devices.