Laser Induce Fluorescence (LIF) is a widely used new telemetry technology. It obtains information about oil spill and oil film thickness by analyzing the characteristics of stimulated fluorescence and has an important application in the field of rapid analysis of water composition. A set of LIF detection system for marine oil pollution is designed in this paper, which uses 355nm high-energy pulsed laser as the excitation light source. A high-sensitivity image intensifier is used in the detector. The upper machine sends a digital signal through a serial port to achieve nanoseconds range-gated width control for image intensifier. The target fluorescence spectrum image is displayed on the image intensifier by adjusting the delay time and the width of the pulse signal. The spectral image is coupled to CCD by lens imaging to achieve spectral display and data analysis function by computer. The system is used to detect the surface of the floating oil film in the distance of 25m to obtain the fluorescence spectra of different oil products respectively. The fluorescence spectra of oil products are obvious. The experimental results show that the system can realize high-precision long-range fluorescence detection and reflect the fluorescence characteristics of the target accurately, with broad application prospects in marine oil pollution identification and oil film thickness detection.
We present an optical receiving system for LIF lidar using a direct view spectrometer based on holographic grating prism. The proposed receiving optical system consists of receiving telescope, slit, collimating lens, holographic grating prism, objective lens and ICCD camera. The receiving optical system based on this dispersion structure can not only reduces the optical distortion to offer a high optical efficiency, but also has a more compact structure which is very suitable for spectral dispersion of remote target. The system adopted an intensifier coupled a CCD to make up an ICCD camera. Based on real-time background subtraction algorithm, 60fps fluorescence spectrum can be obtained in real time. System validation experiment uses a semiconductor laser as excitation source to illuminate oil target to radiate fluorescence at a distance of 30 m. The fluorescent signal is received by the set up LIF lidar receiving optical system, and clear spectrum image is obtained. The designed in-line, direct view configuration holographic grating prism spectrometer owns the advantages of high light throughput, less optical distortions, compact structure, small volume and easy operation, which make a practical portable receiving optical system.
In this paper, we present a prism spectrometer that exploits a double Amici prism dispersion structure. The system consists of a slit, a collimating lens, a double Amici prism, an imaging lens and a CCD. The incident light enter into slit, and then is paralleled by a collimating lens to the double Amici prism. The double Amici prism is used to realize spectral dispersion. The dispersed light is collected by an imaging lens and image on the photosensitive surface of the CCD. The dispersion resolution is theoretical analyzed from the ray tracing point of view. In addition, the imaging position on CCD element at different wavelength is presented according to nonlinear curve of dispersion. The designed prism spectrometer can obtain a high light throughput and less optical distortion spectrum in the spectral range of 370-700nm. In experiment, we measured the spectral resolution of the designed prism spectrometer at five wavelength used a grating monochromator. The designed in-line, direct view configuration prism spectrometer owns the advantages of high light throughput, less optical distortions, compact structure, small volume and easy operation, which has important role in application of laser spectral measurement especially laser remote sensing spectral detection.
A method using rotating Fabry–Perot (FP) mirror to measure CO2 laser wavelength was developed. The variation of FP transmittance changing with laser incident angle was calculated theoretically and the variation curve was given. The calculation illustrates that the variation of FP reflectance with incident angle 0 to 30 deg has little effect on the transmittance of FP. In the experiments, the CO2 laser transmittance variation of FP was measured at a wavelength of 9.27 μm. To improve the measurement precision of the laser wavelength, the method using the centrosymmetric peaks of FP transmittance curve in the range from −20 to +20 deg of laser incident angle was proposed. The precision of the measurement is about 0.01 μm. The experiment result is consistent with theoretical analysis, which demonstrates the feasibility of the laser wavelength measurement using rotating FP method.
We designed a new solid-state laser with the construction of radial slab array. Three kinds of gain
distributions are considered according to different pumping structure. The numerical calculated results show
that this kind of laser can output high beam quality laser both coherent and incoherent conditions. It is
prospective to be a new research direction for high power, high beam quality, compact and scalable solid
The Optical nonlinearities and optical limiting (OL) properties of Sol-gel solidified gold nanorods were investigated by using Z-scan technique and OL measurement, respectively, with nanosecond pulses at 532nm. The experimental results show that their strong nonlinear optical performances depend on the sizes of nanorods. The surface plasmon absorption is the main mechanism.