A multi-modules all-fiber terahertz spectrum system has been designed and built to meet the requirement of accurate identification for the different forms of flammable and explosive dangerous articles in the anti-terrorism goods detection. After that, two different forms of flammable and explosive dangerous goods have been detected to test the system. The results of the test clearly showed that all of the dangerous goods detected by the terahertz spectrum system have obvious characteristic absorption peaks in the range of 0.1～2 THz. On the basis of the detecting results which have been mentioned above, the flammable and explosive dangerous goods may be identified. What's more, it also offers a possible way for public safety inspection.

Segmentation of ultrasound breast tumors using seed region growth is a common method of computer-aided diagnosis. In order to realize automatic and fast locating of seed points, the demand of real-time online image segmentation is satisfied. According to the structural characteristics of ultrasound breast tumor image, and integrating the gray and spatial factors of the image, an algorithm based on iterative quadtree decomposition is proposed to transform the image splitting which meets a specific threshold into searching for seed regions, so as to realize automatic seed location. The verification results of 105 ultrasound breast tumor images show that this method not only satisfies the requirement of automatic location of the seed point within the tumor, with an accuracy of 94.28%. The average time consumed is 2.97 s. This method is also requires few parameters to be adjusted. Compared with other methods, the proposed method is more efficient.

In order to detect potato late blight quickly and compare the difference of spatial spectrum information, hyperspectral imaging technology was used to compare the spatial spectrum of potato late blight in order to find the best discriminant method. A hyperspectral camera was used to collect the hyperspectral images of 0?6 days of disease infection. At the same time, the hyperspectral data of typical late blight diseases on the 6th day were selected as the research object. Second-order derivative combined with principal component analysis and second-order principal component analysis were used to extract features from spectral and spatial aspects respectively. Then, K-nearest neighbor classification algorithm, BP neural network and decision tree algorithm were established based on the reflectance of characteristic band and the gray value of principal component image to identify diseases in different periods. The recognition rate of the model was 96.6% based on the gray value of the secondary principal component image and BP neural network. The experimental results showed that the model based on the gray value of the secondary principal component image and BP neural network had good effect on the identification of potato late blight. The three models based on the gray value of the principal component image reduce the redundancy of the band and improve the recognition rate, which provides a reference for researching and developing real-time on-line testing equipment and instruments..

In view of the current situation that the optical coherence tomography (OCT) scanner has poor stability in clinical use, is easy to cause signal attenuation, and has short maintenance cycle, this paper collects clinical signal attenuation fault information by sampling from the mainstream 4-generation frequency-domain optical coherence tomography equipment in the market. Combining with the principle of OCT, we analyze the influence of internal components of OCT on stability by statistical principle, and the weight of each influence factor on the stability of OCT through analytic hierarchy process (AHP). According to the analysis results, the main factor affecting the long-term stability of OCT is that the spectrometer is locally heated to cause mechanical deformation, which leads to signal attenuation. At last, according to the analytic hierarchy process, we briefly discuss the methods to improve the long-term stability of OCT.

In order to improve the detection sensitivity of Raman spectrometer, a copper-based surface-enhanced Raman scattering film substrate was designed. A series of copper-titanium alloy films were obtained by controlling the magnetron sputtering parameters with Cu40Ti60 alloy target. The copper-based films with different structures were systematically studied. The effects of different sputtering parameters on surface enhanced Raman scattering (SERS） characteristics of the copper-based films were investigated. The optimal sputtering parameters for the preparation of SERS substrates were determined. The copper film obtained after dealloying has a porous structure and can form a high-intensity local electromagnetic field, that is, SERS "hotspots", thereby exhibiting excellent SERS enhancement performance. The substrate is low in cost and good in repeatability by magnetron sputtering, and can achieve sensitive detection and SERS enhancement factor up to 1.8×107. It is one of the ideal choices for high performance SERS substrates and has a high application prospect.

This paper presents a 16-slot continuous transverse stub (CTS) array antenna that can achieve high gain, high efficiency and lower transmission loss. The antenna can reduce losses and increase radiation efficiency by using series connection stubs. To improve the impedance matching and the directivity, the CTS unit is fed by a combination of a power divider and a radiator. The proposed antenna can exactly operate on dual-frequency. The designed CTS array antenna is simulated by HFSS. The simulated results show that S11 is less than ?10 dB from 75 GHz to 80 GHz and from 85 GHz to 89 GHz. The peak gain reaches 28.6 dB at 78.8 GHz and 28.4 dB at 87.5 GHz. Antenna aperture efficiency is higher than 50% and the main beamwidth of antenna is about 4.4°.

The deflector obtains the directional propagation of electromagnetic wave, and plays an important role in sensing and optical communication. The chromatic problem causes the deflection angle varying with wavelength, which limits the application scope of the deflector. In order to achieve achromatic aberration, in this paper, we analyze the physical mechanism of the chromatic aberration and realize achromatic terahertz deflectors using the geometric and resonant compensation phase, which are composed by the all-dielectric metasurface. In addition, the simulations of the achromatic effect are carried out by the finite difference time domain (FDTD) method within a continue frequency range from 0.5 to 1.1 THz.

We design a terahertz monolayer graphene-based modulator using the property of voltage-tunable optical conductivity of graphene. In order to enhance the graphene-terahertz interaction strength, a metal-graphene hybrid structure is used to construct the modulator. The full-wave electromagnetic simulations show that the modulation depth is larger than 90% at 3.5 THz in the reflection operation mode. The prototype device is fabricated with planar semiconductor fabrication processes. The reflection spectra of the device are measured. The experimental data are in good agreement with the simulation results. The method is helpful for realizing high performance terahertz modulators.

The synthesis of nanoparticles by pulsed laser ablation in liquid is a green and environmental-friendly method. Based on this method, a set of induum tin oxide ITO nanoparticles preparation system was built, which used picosecond laser as a light source to irradiate the solid target of ITO in deionized water, and finally synthesized ITO nanoparticles. With the increase of incident pulse energy and laser irradiation time, the laser ablation efficiency increased obviously and ITO production increased. The ITO nanoparticles were characterized by scanning electron microscopy (SEM) and X-ray energy dispersive spectrometer (EDS). The prepared ITO nanoparticles have high purity and did not contain impurities other than Indium (In) and Tin (Sn). In addition, 72% of the ITO nanoparticles had a particle size of 20?50 nm.

In order to solve the fluorescence excitation problem of high throughput dPCR gene chip, a fluorescence excitation measurement and control system was designed in this paper. According to the excitation spectrum characteristics of fluorescent dyes, high-power narrow-band LED is selected as the fluorescent excitation light source and controlled by STM32 microprocessor system. The fluorescence excitation system has three fluorescence excitation channels including FAM, HEX and ROX, and the excitation power of each LED channel can be adjusted respectively. The maximum output current of the system is 8 A, the maximum output power of the single channel is 3 W, and the adjustment accuracy is less than 1.0%. The system could complete the fluorescence excitation and collection of 9 600 microdroplets of dPCR gene chip at one time. The experimental results show that the system meets the requirements of design and application.

Intelligent vehicles use a lidar-camera sensor fusion system to perceive the environment. Two calibration methods, feature point method and checkerboard method, are proposed for the joint calibration of different sensor coordinate systems in the data fusion. The feature-point method employs a tailored calibration template to extract several pairs of corresponding points, and solves the constraint equations for the calibration parameters in virtue of the least square method. The checkerboard method employs Zhang’s calibration method to obtain the intrinsic parameters of the camera. And then, equations are derived by using the consistency of the checkerboard plane in lidar and camera coordinate systems, solving the extrinsic parameters between the two coordinates using a linear method. The result is further refined by a nonlinear optimization method. The lidar points are projected onto the image plane by using the calibration results obtained from the two methods. Experiments demonstrate that the two methods are capable of obtaining the accurate position parameters between the coordinate systems of each sensor. The projection alignment errors are 3.03 pixels for the feature point method and 2.33 pixels for the checkerboard method.

The combustion environment of pulverized coal particles is provided by the flat flame entrained flow combustor system based on McKenna burner. The moving coal particles are photographed by a color camera imaging system, which is calibrated by a black body furnace. The temperature of the combustion coal particles is measured based on the two-color method using the responses of the r and g channels. The calibration of the temperature measurement system is carried out based on the BP neural network training method. By photographing the burning flame of the candle, the results are compared with the thermocouple data to verify the reliability of the temperature measuring system. The experimental study obtained the temperature information of the coal particles at different distances from the burner exit. The results show that the temperature of the coal particles rises first and then decreases along the height of the nozzle outlet. The acquisition of temperature information provides a data reference for studying the combustion process and ignition mechanism of pulverized coal. The system can be combined with the backlight imaging system to form a dual optical path system for simultaneous experimental research.

Based on terahertz time-domain spectroscopy and prism attenuated total reflection technique, we design a non-invasive blood glucose detection system with terahertz wave reflectance spectroscopy. With the help of Debye model, it is found that the change of water content in the skin can affect the relaxation of the skin in terahertz band. The relationship between the complex refractive index of the skin and the water content of the skin is obtained. The method of calculating the real part and imaginary part of skin refractive index is given by means of Fresnel formula. The real and imaginary parts of the complex refractive index of human thumb skin measured by terahertz spectroscopy are compared with the actual human blood glucose concentration measured by oral glucose tolerance test. The relationship between the terahertz reflection spectrum and complex refractive index of human thumb skin are positively correlated with human blood glucose concentration. It provides a new method for the application of terahertz in noninvasive blood glucose concentration detection.