Cat-eye Target Research Articles

Three-dimensional echo light field analysis for dual-band laser active detection of a cat-eye optical system.

Laser active detection technology utilizing the cat-eye effect provides rapid response, precise positioning, and long detection distances. However, current research mainly focuses on active detection within a single visible or near-infrared band, lacking quantitative analyses of the echo spot. In this paper, a four-interval theoretical model for dual band cat-eye target echo detection was constructed using matrix optics theory and Collins diffraction integration method. Dual-band echo detection experiments were conducted using 10.6 um far-infrared waves and 532 nm visible light waves, also the power, radius, and target-missing quantities of the echo spots were collected and quantitatively compared with the theoretical results. Results indicate that, due to the diffraction limit's effect on the distribution of the echo field, the echo power of far-infrared band detection is smaller than that of visible light band detection. The impact on the light spot caused by the positive and negative defocus values is asymmetric, with positive defocus having a lower impact on the echo spot than negative defocus at the same value. A weak positive defocus value that minimizes the radius of the echo spot and maximizes the echo power exists, with the value of weak positive defocus varying between detection bands. A linear relationship exists between the incident angle of the detection laser and the deviation of the echo spot. These findings provide a foundation for extracting working band details, predicting the motion trajectory of moving cat-eye targets, and achieving real-time tracking and detection recognition during laser active detection.

Three-dimensional echo distribution analysis of multi-band and oblique Gaussian beams propagating through cat-eye optical system

The cat-eye effect in optical systems enables active laser detection at long distances and high orientation precision. However, few studies focus on the influence of a multi-band laser with a large incident angle on the echo distribution. This study proposes a three-dimensional echo distribution calculation model of an obliquely incident multi-band laser based on the Collins diffraction integral formula and aperture function expansion as the sum of complex Gaussian functions. The echo distributions for different detection ranges are calculated by coupling the size of the detector in a cat-eye optical system into the model. In the numerical simulation, the influences of laser wavelength, incident angle, and target detector parameter are quantitatively analysed by introducing a target-missing quantity of echo spot and peak light intensity. The results show that the peak light intensity decreases with an increase in incident laser wavelength. When the incident angle increases to a particular value, the peak light intensity decreases sharply, and the target-missing quantity of the echo spot centroid is positively correlated with the incident angle. We can effectively extract important information, such as the working band and detector size, from the cat-eye target echo using this model and provide a trajectory prediction theory for the active detection of a cat-eye target moving at high speed.

Active laser detection system for recognizing surveillance devices

In recent years, we have seen proliferation in the presence of surveillance devices such as cameras and commercial unmanned aircraft vehicles (UAVs). These devices have posed ever-increasing security threats. This paper proposes an active laser detection system to counter surveillance components by exploiting cat-eye effect. We first establish a cat-eye target detection model and the calculation results show that our proposals are capable of achieving results comparable to those generated by thermal detection systems but more cost effective. We also investigate the properties of reflected spots generated by cat-eye targets, and formulate corresponding recognition criteria. Using our hardware platform and the proposed algorithms, our experiments produce the recognition of static cat-eye targets at a wide range of operating distances, as well as the real-time identification of moving cat-eye targets. These results have not been achieved before, to the best of our knowledge. The entire system can be applied not only for the detection of a wide categories of stationary monitoring targets with cat-eye configurations including cameras and optical sights, but also for tracking and confronting moving surveillance devices such as UAVs.

Periodicity analysis on cat-eye reflected beam profiles of optical detectors

The cat-eye effect reflected beam profiles of most optical detectors have a certain characteristic of periodicity, which is caused by array arrangement of sensors at their optical focal planes. It is the first time to find and prove that the reflected beam profile becomes several periodic spots at the reflected propagation distance corresponding to half the imaging distance of a CCD camera. Furthermore, the spatial cycle of these spots is approximately constant, independent of the CCD camera’s imaging distance, which is related only to the focal length and pixel size of the CCD sensor. Thus, we can obtain the imaging distance and intrinsic parameters of the optical detector by analyzing its cat-eye reflected beam profiles. This conclusion can be applied in the field of non-cooperative cat-eye target recognition.

Cat-eye effect reflected beam profiles of an optical system with sensor array.

In this paper, we propose an applicable propagation model for Gaussian beams passing through any cat-eye target instead of traditional simplification consisting of only a mirror placed at the focal plane of a lens. According to the model, the cat-eye effect of CCD cameras affected by defocus is numerically simulated. An excellent agreement of experiment results with theoretical analysis is obtained. It is found that the reflectivity distribution at the focal plane of the cat-eye optical lens has great influence on the results, while the cat-eye effect reflected beam profiles of CCD cameras show obvious periodicity.

Cat-eye target recognition with image registration of dual-CCD

With the development of optoelectronic surveillance, tracking and optical communication technology, high efficient and reliable target recognition algorithm, especially cat-eye effect target recognition algorithm, becomes more and more important. However, the accuracy and efficiency have been difficult to guarantee. To solve these problems, a cat-eye effect target recognition method based on image registration (CEIR) of dual-CCD is proposed. In this method, before difference operation, image registration is applied to correct corresponding mismatching points. Besides, in the CEIR, an improved algorithm for the exhaustive algorithm is proposed to shorten the running time and improve the correctness of the exhaustive algorithm. Experimental results show that the CEIR is capable of recognizing cat-eye effect targets in static and dynamic background. The CEIR can remove dynamic background distraction and extract cat-eye effect targets with only one pair of images. The CEIR is more efficient in the running time than the shape-frequency dual criterions (SFDC) method.

Fast cat-eye effect target recognition based on saliency extraction

Background complexity is a main reason that results in false detection in cat-eye target recognition. Human vision has selective attention property which can help search the salient target from complex unknown scenes quickly and precisely. In the paper, we propose a novel cat-eye effect target recognition method named Multi-channel Saliency Processing before Fusion (MSPF). This method combines traditional cat-eye target recognition with the selective characters of visual attention. Furthermore, parallel processing enables it to achieve fast recognition. Experimental results show that the proposed method performs better in accuracy, robustness and speed compared to other methods.

基于嵌入式平台的猫眼效应目标实时探测系统研究

基于嵌入式平台的猫眼效应目标实时探测系统研究

Theoretical Analysis on Retro-Reflected Wave Power Based on “Cat-Eye” Effect in Defocusing Condition

Retro-reflected wave power of cat-eye target is an important factor for active laser detection system, which can evaluate high or low cat-eye effect of photoelectrical device. Theoretical and experimental results show that retro-reflected wave power will rapidly decline with defocusing distance increases and the decline more notable in negative defocusing condition.

相干合成线阵高斯光束扫描识别猫眼目标理论分析

相干合成线阵高斯光束扫描识别猫眼目标理论分析

基于形状和调制频率双重判据的猫眼效应目标识别算法

We present an image recognition method to distinguish targets with cat-eye effect from the dynamic background based on target shape and modulation frequency. Original image sequences to be processed are acquired through an imaging mechanism that utilizes a pulsed laser as active illuminator and an industrial camera as detection device. There are two criterions to recognize a target: one exploits shape priors and the other is the active illuminator's modulation frequency. The feasibility of the proposed method and its superiority over the single criterion method have been demonstrated by practical experiments.

基于形状和调制频率双重判据的猫眼效应目标识别算法

基于形状和调制频率双重判据的猫眼效应目标识别算法

Recognizing cat-eye targets with dual criterions of shape and modulation frequency

Recognizing cat-eye targets with dual criterions of shape and modulation frequency

相干合成线阵高斯光束扫描识别猫眼目标理论分析

相干合成线阵高斯光束扫描识别猫眼目标理论分析

相干合成线阵高斯光束扫描识别猫眼目标理论分析

相干合成线阵高斯光束扫描识别猫眼目标理论分析