Due to the local variations of the electric-field vector caused by a single gold nanoparticle in the near-field, a new method of detecting near-field polarization states is proposed. A gold nanoparticle array with a radius of 50 nm is designed to detect the electric-field vector of different polarization. The gold nanoparticle causes local changes of the electric field vector and produces certain intensity patterns to detect the electric vectors of different polarization states. In this paper, the measurement results of five different polarization states have been mapped by FDTD, which can be distinguished visually and also relative to the different polarization properties.

To determine the surface profile of a sapphire substrate with the change of micrometer scale, a test based on oblique incidence is proposed to extend the measurement range of a interferometer. After studying the theory of oblique incidence measurement principle, the relationship between oblique incidence angle, surface error and wave-front aberration is derived. A simulation model is constructed by Zemax. The influence of surface error and incidence angle on the detection results is investigated. The key parameters such as the best incidence angle are determined in the simulation. The results are used to guide the measurement of 100 mm sapphire substrate on the Fizeau interferometer, the root mean square (RMS) and peak-to-valley (PV) results of the sapphire substrate are 5.182 μm and 1.251 μm. The influence of incidence angle on resolution, sensitivity factor and fringe contrast is discussed. The proposed method can extend the measurement range of interferometer. The result shows the method is suitable for the sapphire substrate with vector height less than 5 μm when the measurement angle is 70°. The error is less than 0.1 μm. The measurement range is upgraded by 1.46 times, and the suitable fringe contrast can be also obtained.

A new and efficient nitric oxide (NO) detection method based on the DAF-FM which is a kind of NO probes was proposed. The incorporation of gold nanoparticles significantly increased the fluorescence intensity of the fluorescent probe after reacting with NO. The new fluorescent probes composed of DAF-FM and gold nanoparticles have dozens of times higher fluorescence intensity than that without gold nanoparticles does. The sensitivity of NO detection has been significantly improved. The new fluorescent probe can be reused for more than 24 times, overcoming the single-use problem of DAF-FM and achieving the sustainable reuse of commercial nitric oxide detection.

The key points of the motion blur image restoration are the acquisition of the blur angle and length. This paper proposes two methods for improving detection accuracy of the cross bright line impact angle in the spectrum image of the motion blur image. On the basis of Radon transform, the effect of cross bright line pair detection accuracy is reduced by decentralizing the spectrum of the blurred image, and performing secondary Fourier transform to refine the fringe information. After comparative experiments, it was found that the two methods could improve the detection accuracy by about 1° to 3°.

To achieve high-precision cone inner surface measurement, it is necessary to identify the cause of error and analyze the influence of the error on the measurement result. By building the mathematical model in the cylindrical coordinate system, the formulas of offset error and angle error are derived. The result shows that the optical path difference is caused obviously by offset error and angle error of cone mirror. When the offset is extremely small, the optical path difference changes linearly with the offset. The optical path is very sensitive to angle error. To ensure the measurement accuracy, the apex angle of cone mirror must be strictly controlled.

In this paper, we propose a substance identification method based on multiple terahertz time-domain spectroscopy (THz-TDS) systems. Spectral data from different THz-TDS systems were analyzed by wavelet transform to remove the noise and baseline. Then, the standardized data can be obtained by mapping the sampling frequencies to the same with cubic spline interpolation, which is used as the feature vector of the support vector machine (SVM). Finally, the spectral identification accuracy can be up to 98.33% with an appropriate kernel function and the optimization parameters based on grid search. These results are meaningful for the eventual practical application of exact substance identification.

Femtosecond optical frequency comb has been a rich research field in laser optics. We demonstrated an all polarization-maintaining (PM) fiber, Erbium-doped frequency comb based on a nonlinear amplification loop mirror(NALM) mode-locked fiber laser. An integrated nonreciprocal phase shifter was employed in a passively mode-locked NALM-based oscillator to reduce the mode locking threshold and facilitate self-starting. Being amplified and pulse compressed, the peak power of the pulses can achieve as high as 61.3 kW. Injecting the high-power ultrashort pulses into a 55-cm-long PM high nonlinear fiber (HNLF), an octave-spanning supercontinuum from 1 030 nm to 2 200 nm was generated. By using a collinear f-2f interferometer, the carrier-envelop offset signal (f0) with 40-dB signal-to-noise ratio (SNR) and 40-kHz linewidth was detected. Moreover, with the employment of two feedback locking electronics, the f0 signal and the repetition rate of the laser (fr) were phase-locked and it showed the standard deviations of 521.71 mHz and 240 μHz, respectively.

In order to solve the problem that the encrypted image can be cracked easily and protect the copyright of related products, this paper adopts a digital blind watermarking algorithm based on block DCT transform. After the image is divided into blocks, the DCT transform is performed, and the spatial domain is transformed into the frequency domain. Then, we can embed and extract the watermark into the image. Finally, in the experiment about the digital watermarking algorithm based on wavelet transform domain, we found that the proposed algorithm can provide good watermark transparency for images with peak signal-to-noise ratio of 52.588 3 dB. And it has good performance to avoid noise and shear. This method has good robustness.

Continuous zoom optical system has extensive and essential practical applications in the field, such as law enforcement and evidence collection, forest fire, maritime search rescue, road traffic, unmanned aerial vehicle reconnaissance. In order to improve the zoom system performance index, and realize the miniaturization of system, the focal length of 2.68 mm to 17.5 mm, 4.7°-31° field zoom system is designed by using the Zemax optical design software and optimization calculation. The whole system is composed of four groups of ten pieces of lens. The F number is 2.15-3. The MTF curve at 250 lp/mm is greater than 0.25. Distortion is within 4.5%. The optical length is less than 27 mm. Total mass is less than 0.77 g. The system has a compact structure, light weight, high resolution, excellent image quality, etc, which is a miniaturization of microminiature continuous zoom.

Laser speckle contrast imaging (LSCI) technology can provide non-invasive and highly effective therapeutic evaluation method for traditional chinese medicine physical therapy. However, the stability of this assessment method needs to be improved. Based on near infrared laser light source, the speckle imaging experiment was performed and the original experimental data was obtained. The data processing results of the new contrast processing algorithm based on RT(Roll with time-sampling) were analyzed. It can be seen that based on the regularity of the contrast distribution the distribution obtained by the RT algorithm was more even as some of the noise was filtered. Therefore, RT algorithm could improve the stability of the laser speckle contrast distribution.

In this paper, we present performance optimization for a home-built scattering-type scanning near-field optical microscope. We studied the influence of both the vibration amplitude and the amplitude setpoint of scattering tip on background suppression and near-field signal extraction. It’s demonstrated that the amplitude of small vibration similar to the size of tip climax is beneficial to suppress background related to far-field scattering from probe shaft and cantilever. In order to reduce the influence of vibration harmonics on signal demodulation during probe scanning, the ratio of feedback amplitude setpoint to free space vibration amplitude must be 90% at least.

With eight-channel Kirkpatrick-Baez (KB) X-ray microscope applied to China's Shenguang-Ⅲ (SG-Ⅲ) laser facility, the effect of aiming error on imaging performance and the consistency of multichannel KB microscope were analyzed. The spatial resolution, image interval and system efficiency of X-ray microscope were simulated by ray-tracing model as a function of the field of view (FOV), object distance and image distance, respectively. The spatial resolution decreased by about 2.9 μm within range of ±200 μm and the efficiency of microscope system declined by about 60% within range of ±150 μm. The change of image interval and the efficiency of the microscope system were 0.67 mm and 7% respectively, when variety of object distance was changed within ±200 μm. The change of image interval was about 0.70 mm, when the image distance varies within range of ±20 mm. The results indicated that the aiming error of central FOV had a great effect on spatial resolution and system efficiency but it had no significant effect on image interval. The aiming error of object distance has impact upon image interval while it has lower influence on spatial resolution and system efficiency.

In order to coordinate with the clinical implementation of intraocular lens diopter calculation, and to provide basis for the prevention of eye diseases, the measurement of ocular biological parameters, especially the axial eye length, has attracted more and more attention. This paper mainly discusses the existing measurement methods of axial eye length, which includes traditional ultrasonic measurement method and optical measurement method. This mainly summarizes progress of the measurements of the axial eye length in the partial coherence interferometry, optical low coherence reflectometry and optical coherence tomography. The measurement principle, measurement precision and range of each method and typical instrument are introduced. The development direction of axial eye length measurement is discussed. The ultrasonic measurement method has been gradually replaced by the optical measurement method with the advantages of no damage, rapid and high precision. However, it is necessary to rely on ultrasonic measurement for eyes which lens is opacity.

The metamaterial is an artificial composite material. It is generally composed of a unit structure in which metals and dielectrics are periodically arranged. It has certain special electromagnetic properties that are not available in the natural materials. The electromagnetic response of metamaterials is determined not only by its constituent materials but also by its microstructure and arrangement. The perfect absorber based on metamaterial design can achieve close to 100% absorption of electromagnetic waves of a specific wavelength by rationally changing the microstructure parameters and arrangement of the resonant units. Perfect metamaterial absorber (PMA), with the advantages of flexible design, adjustable response, small thickness, strong wave absorption, etc., is possible to achieve ultra-wide bandwidth and extremely narrow bandwidth through a well-designed structure, which can be widely used for stealth materials, frequency selective surfaces, terahertz imaging, intelligent communications, photoelectric detection, and other fields. This review summarizes the research status and development prospects of PMA on the basis of comprehensive research status at home and abroad in order to obtain a more comprehensive understanding of PMA. Finally, the PMA development trend and application prospects are thoroughly discussed. The new PMA with multi-function and simple structure is the future development trend.

Sonoluminescence is a phenomenon that when a liquid is subjected to a powerful sound wave, a “sound cavitation” is yielded in the liquid, which means a bubble is generated in the liquid and is instantaneously reduced to a very small volume, and an instant flash is produced with a large amount of heat released in the process. Sonoluminescence as an interdisciplinary subject between acoustics and optics has now attracted a lot of interest. This paper systematically reviews the peculiar phenomenon of sonoluminescence, discusses several mechanisms of sonoluminescence, introduces the research progress of single-bubble sonoluminescence and multi-bubble sonoluminescence and the latest research results in various fields, and proposes prospects for the future development and application of sonoluminescence.