A portable and modularized fluorometer based on optical fiber was proposed in this work. The fluorometer included a light emitter diode (LED) light source module (LSM), a sample cell module (SCM), an optical-electrical converter module (OCM) and a signal process module (SAM). The LEDs in LSM were driven by a constant current source to provide stable exciting light with different wavelength. The OCM included a modularized optical filter and used a photomultiplier tube (PMT) to detect fluorescence signal. The SCM was used to locate sample cuvette and could be connected by optical fibers with the LSM and OCM. Via modularized design, the LSM and OCM could both selected and replaced based on different fluorescence dyes. In order to improve the detecting dynamic range of the fluorometer, the SAM could control the light intensity of LED source in LSM, to control the gain of PMT in OCM, and particularly, four channel signal acquisition circuits with different gain were constructed to collect fluorescence signal simultaneously. Fluorescein isothiocyanate (FITC) was selected as sample to test the fluorometer. The fluorometer has shown a high sensitivity with FITC concentration of 10ng/mL and presented a good linearity from 10 ng/mL to 10 μg/mL.
This paper reports the theoretical and experimental vibrational spectra of the histidine in the frequency range between 0~
10.0 and 0.2~2.8 THz (FIR) respectively. Seven absorption peaks have been calculated out by using the semi-empirical
theory and PM3 algorithm. The characteristic absorption peaks are attributed to torsional vibration modes of the molecule
based on the semi-empirical theory. Three experimental peaks obtained from terahertz time-domain spectroscopy
(THz-TDS) are comparable with the first three calculated peaks and these results mutually validated both approaches,
although other four theoretical peaks between 2.8~10.0 THz remain to be tested in future.
A new experiment method for recording the hologram by CCD with less distortion and reconstructing the original image with high quality is described in this paper. The feature of this developed method is that conjugate and zero-order image can be eliminated simultaneously by setting their spectrum zero in spatial domain. The results have demonstrated that it is an efficient method of image acquisition and the reconstruction with high quality in digital holography.
Terahertz (THz) region occupies the portion of the electromagnetic spectrum between the infrared and microwave bands, with the frequency range from 0.1THz to 10THz (10×1012Hz). Because THz radiation was difficult to generate and detect, the characters of THz had been unknown for a long time. Now, there are two primarily classes method to generate and detect THz wave, including continues THz wave system and pulsed THz system. Among them, pulsed THz system is based on ultra-fast pulsed generation and detection using mode-locked lasers which only became commonly available in the late 1980s. Relying on pulsed THz system, THz pulse spectroscopy, also called THz time-domain spectroscopy (THz-TDS) has been applied in study of the characters of materials over the last decade. In such a short period, because of the large variety and complicacy of big bio-molecules, many different THz pulse spectroscopy methods have been developed to study their collective vibration modes, but not been systematically summarized yet. In order to promote the THz pulse spectroscopy, this paper provides a general review of the achievements using the technology in study of biological molecules, particularly focusing on the technology and the advancement in sample preparation, optical path design, data processing and spectrum analysis.