In order to detect and analyze the number and size of particulate matter in liquid media, the characterization of standard spherical particles were investigated by the method of light-blockage related to geometric optics and Mie scattering theory, while the method of angle scattering and the image method were used to verify the consistency of the measurement. A system was established that could be available simultaneously for the three methods. To perform a calibration, the amplitudes of obtained light-blockage signal for standard particles with six different sizes were statistically averaged and fitted, which consequently provided a fitting formula to determine the measurement results of other particles. The results for two standard particles and a mixed particle system showed that the median diameters for particles with nominal value of both 15.0 μm and 63.6 μm yielded a deviation less than 2%, and the mixed particles were also well identified in size.

In order to solve the depolarization effect of the corner cube, an elliptically polarized light correction scheme with the external wave plates is proposed. The modified formula of the corner cube with a tilted solid ridgeline is summarized, and a polarized light correction model with clockwise and counter-clockwise reflection paths is established. The analysis of the model shows that two half-wave plates and one retarder can keep the polarization state of the incident ray equal to that of the emerging ray. Based on the model, by using a 1 064 nm laser, the correction experiment on the BK7 glass corner cube whose solid ridgeline is placed vertically in clockwise and counter-clockwise reflection paths is carried out. When the angle between the polarized direction and the horizontal direction of the linearly polarized incident light varies from 90° to 0°, the maximum absolute value of the ellipticity of the light in depolarization is corrected from 35° to 5°. When the incident light is with the approximately circular polarization, its ellipticity drops from 44° to 40° after correction.

In order to increase the imaging speed of the laser confocal scanning microscope, a progressive bidirectional scanning method should be used in order to make full use of the highest frequency that the scanning galvanometer can achieve. Meanwhile, for high-speed scanning image this method will bring frame data segmentation problems. In this paper, on the basis of qualitative analysis of the system scanning mode and taking full account of the differences between the actual and theoretical motion modes of galvanometer, a set of complete high-frame-rate imaging algorithms is proposed by exploiting the similarity of two adjacent frames. The method realizes adaptive segmentation of one-dimensional signal sequence by means of continuous frame feature region difference, that is , the one-dimensional signal sequence is dynamically arranged and divided into two-dimensional array image data, thereby reconstructing multi-frame high-precision images. Experiment shows that the imaging error of this algorithm is less than 1.6% and is suitable for laser confocal scanning microscopy with an imaging speed of up to 300 frame/s.

To meet the need of ultra-precision polishing of optical aspheric elements with high precision, the motion control algorithm is designed for magnetic compound fluid polishing of aspheric magnetic components. Optical aspheric magnetic compound fluid polishing principle is analyzed. The relation between the configuration of the polishing head and the aspheric surface is established. The D-H method is used to establish the kinematics model of the polishing test platform and the head posture during the polishing process is solved. Process experiments are carried out to verify the motion control algorithm. Experimental results show that the designed motion control algorithm can process optical aspherical elements reasonably.

In order to overcome the limitations of the Mie scattering method based on approximate theoretical analysis in the study of particle size smaller than the incident light wavelength, this paper used the finite difference time domain (FDTD) method based on numerical simulation to scatter nano-scale. The effect of bulk particles on the near-field focused beam was simulated. The FDTD simulation software was used to simulate the light intensity distribution information around the nano-air particles with the focused linearly polarized light as the light source and the spherical nano-air particles embedded in the beam focus point of the bottom surface of the solid immersion lens. A good focus imaging effect is achieved by changing the corresponding simulation conditions.

The study of the resonance characteristics of sub-wavelength gratings has always been one of the most important part of optics. In this paper, a sub-wavelength one-dimensional grating design based on Fano resonance is proposed. Compared with the guided-mode resonance, the Fano resonance has stronger near-field enhancement, finer spectrum and higher sensing quality factor. The optical simulation software, FDTD Solutions, is used to simulate the structure of the grating. The parameters affecting the diffraction performance of the grating are studied in detail, including the period, refractive index and duty ratio of the grating. The simulation results show that Fano resonance lines have high resonance intensities, fine spectral lines and controllable resonance positions in the visible light region. Based on this discovery, the one-dimensional grating structures proposed in this work could be utilized as a wavelength selector with an accuracy of less than 1 nm.

With the increasing commercial application of free-form surfaces, the profile measurement capability of related molds and optical components has become a key bottleneck in the development and application of free-form optics, and the demand for free-form optics inspection tools is also increasing. In this paper, we developed an integrated free-form optics profile measurement system based on the fringe reflection principle, and the system is also combined with a laser stripe stereo vision measurement capability. The developed system is capable of measuring both rough surfaces and smooth optical surfaces. The measurement experiments prove that the current developed system can measure free-form optics with a diagonal size of approximately 300 mm, and the measurement uncertainty within ±1 μm.

In order to improve the quality of the paper, raise the employment rate of the paper, improve the readability of the paper, through long-term reading and processing, this paper summarizes the common problem of the tile, abstract, introduction, body, formula, figure, table, quantity and unit, reference documents of the submitted papers on Optical Instruments, and give some examples and suggestions, hoping to help the authors’ thesis writing.

Crossline center detection is an important part of reflective method for measuring lens center deviation. The detection accuracy of the cross center determines the measurement accuracy of the lens center-offset to some extent. Aiming at the image with irregular edge, poor contrast and low signal-to-noise ratio, a cross-line center detection algorithm based on depth convolution neural network is proposed. The idea of the algorithm is that the convolution neural network can solve the problem that the traditional algorithm is limited to extracting the line and corner features of the edge of the cross image to a certain extent, and realize the recognition and location of the overall features of the cross image. This can relatively reduce the impact of image noise on the location of the cross image center, so as to achieve the accurate location of the cross image center in the case of poor image quality. The experimental results show that the proposed algorithm can get the center of the cross line accurately under the conditions of irregular edges, poor contrast and low signal-to-noise ratio.

In order to further reveal the mechanism of ultrasonic vibration assisted grinding, a prediction model of the ultrasonic vibration assisted grinding subsurface damage depth and fracture toughness was established. The single random-shape diamond grit indentation experiments without ultrasonic vibration and ultrasonic vibration assisted grinding experiments were designed. The indentation features of K9 optical glass in the two cases were investigated. A calculation method of equivalent fracture toughness suitable for two cases was proposed. The reliability of the model is verified by ultrasonic vibration assisted grinding experiments. The experimental results show that ultrasonic vibration can effectively increase the resistance of K9 optical glass to fracture, and the prediction model has a good consistency with the test results.

According to the accuracy requirements of aspheric components in the optical systems, the linear grating polishing trajectory of magnetic compound fluid polishing is designed to polish aspheric compoents. Based on the polishing trajectory and the aspheric equation, the coordinates of each polishing processing point are calculated. The coordinates of the center point of the polishing head are calculated according to each polishing point and the polishing head which is relative to the geometry of the workpiece. The model of high-height error between each polishing point is established, and the variation rule of the surface arch error of workpiece is simulated by the model. According to the variation rule of the surface arch error, the equal arch error control algorithm is used to achieve arch error consistency and improve processing quality.

In order to study the influence of interface reflection on terahertz (THz) spectroscopy of double compression tablets, the THz time-domain spectroscopy (THz-TDS) was used to detect the single- and two-layer sand tablets made of different particle sizes, and the THz-TDS were obtained. The results show that the THz peak attenuation coefficient of the unit thickness of the double-layer sample was significantly smaller than that of the single-layer sample. Therefore, a coefficient should be added to study THz spectral response of double-layer samples to eliminate the loss caused by interface reflection of samples, and the coefficient was related to the characteristics of materials.

A miniaturized, low-radiation X-ray flying-spot scanning backscattering system was developed around the precise and rapid investigation of trafficking contraband by vehicles. A chopper mechanism and a backscatter detector for miniaturized flying-spot scanning backscattering systems were designed. The X-ray backscatter imaging experiment was carried out by using the developed miniaturized flying-spot scanning system. The effects of X-ray energy and power on the imaging contrast and signal-to-noise ratio of the system were studied. The developed system has an imaging resolution of approximately 2 mm and is capable of clearly detecting drug mimics hidden in ceramic articles. The research of miniaturized X-ray backscattering system can provide reference for vehicle security problems and reduce radiation hazards in testing.

Aiming at the problem that the non-invasive blood pressure measuring instrument is large and inconvenient to carry and needs professional operation, this paper proposes a non-invasive blood pressure measuring system. Based on the principle of pulse wave conduction and the interaction between light and matter, the system extracts and analyses the photoelectric signal modulus of the skin at the wrist. The arterial blood flow velocity is then calculated, that is, the pulse wave conduction velocity. Finally, the hemorrhagic pressure is calculated. We have tested the performance of the system. The experimental results show that the average relative error between the system and traditional blood pressure measuring instruments is less than 5%. The system is helpful to realize real-time blood pressure monitoring. It has the characteristics of small size, low cost, simple measurement method, easy to carry and large data management. It can be used for human health management.