A scheme for designing a novel optical receiving antenna is proposed to extend the field of view, receive higher power, and reduce the received-energy spot area for indoor visible light communication (VLC). ProE is used to model the antenna, while TracePro and Matlab are employed for simulations. Firstly, the lens wall of a compound parabolic concentrator with a certain rotation angle and thickness is obtained through rotating the parabolic reflector cross-section reference curve. Furthermore, a novel optical receiving antenna is designed in combination with the advantages of the lens-walled CPC and the spherical lens. Then, the Taguchi methodology and ANOVA technique are utilized to optimize the structure parameters of the receiving antenna. Finally, an indoor VLC system model is established and the channel performance is analyzed. Simulation results show that the designed antenna achieves the following performances: optical gain of 21.53, field of view of 45°, and spot size of 3 mm. The received power is 9.5532 dBm, and the SNR is 86.2526 dB, which further confirms that the designed optical receiving antenna is suitable for indoor VLC systems.

Three-dimensional shape measurement plays an important role in various fields. As a way of three-dimensional measurement, fringe projection profilometry (FPP) is widely used because of its non-contact, simple structure, and high stability. One of the key challenges affecting measurement accuracy is the gamma effect. With the development of FPP technology, multi-color channels are gradually applied to the measurement, and the response of different colors in the projector-camera system (pro-cam system) is not exactly the same. Therefore, more accurate gamma correction for different color channels is required. To solve this problem, a model of joint gamma correction for different color channels is proposed. In this model, the light is subdivided into three channels: red; green; and blue (RGB). In the pro-cam system, the different responses of different colors and the influence of background light intensity on gamma correction are comprehensively considered, and some error compensation is made for color crosstalk. Compared with the traditional gamma correction methods, the gamma correction method proposed in this paper is more accurate and has a larger effective working range after correction. This method is particularly beneficial in scenarios where multiple color channels are used for measurement, as it more accurately reflects the true measurement results for each channel. The effectiveness and accuracy of the method are validated through experiments.

The shapes of target surfaces are nonplanar on many occasions such as undulating road and roof of the tunnel, while the lighting quality generated by traditional nonimaging optical lenses still needs to be further improved. As a result, a novel method is proposed for the design of optical elements generating uniform irradiance distribution on nonplanar target surfaces. A matrix is introduced instead of a single height parameter for improving the mathematical model of asymmetrical lenses, hence a modified mathematical model based on single LED chip and desired irradiance distribution of the nonplanar target surface is established. By solving the equations with the iterative method, the asymmetrical lenses can be obtained through commercial CAD tools. Three different nonplanar surfaces are used to verify the validity of the proposed method, including an inner-spherical surface, undulating surface and arched surface. The results show that the illumination uniformity of the target surface can reach over 70%, and the light efficiency is more than 83%, which are much better than that generated by traditional methods.

Tailored illumination have widespread applications such as road lighting. Most road lighting only serves the road but neglects the surroundings which are also important in illumination quality. Therefore, the background illumination is created to solve this problem, finding a balance between road and surroundings. However, optical structures in existing methods still need further processing, and details on energy efficiency are not disclosed either, resulting in a limited practicality. An improved total-internal-reflection (TIR) structure is proposed to generate a complex illumination including a pattern and a circular background. By solving a nonlinear equation which is obtained by converting the pattern problem into the boundary surface problem, the profile curves are optimized, and is then combined into a Lens by a commercial CAD software. The irradiance of the pattern is designed to be twice as much as the background, which can be adjusted by the boundary conditions. The results show that the method can generate the tailored illumination, with the uniformity of pattern and background being 95.3% and 89.3%, respectively, while the light efficiency reaches 86.8%. It can be extended to generate different patterns by modifying the boundary surface applied to road lighting, advertising, entertainment, etc.

As an important branch of computational optics, light field can record the spatial intensity and propagation direction of light simultaneously, which provides a new way to realize three-dimensional (3D) measurement. Although light field measuring system (LFMS) can quickly detect the non-transparent surface, there is also the phenomenon of specular light affecting the overall measurement result. In this paper, a LFMS based on diffused light source and polarization technology is proposed to eliminate specular light and obtain more accurate 3D reconstruction result in one exposure. During the measurement, a series of images corresponding to continuously varying polarization angle are captured, in which value(V)-channel value distribution is used as the criteria of removal efficiency of specular light, and hence the image at the optimal polarization angle is obtained, of which the influence of specular light is removed. The depth map and removal efficiency of specular light influence are experimentally compared with traditional LFMS. The experimental results show that depth map error can be reduced greatly, which further verifies the feasibility of the proposed method and system. The present study can be extended to the traditional optical system or other machine vision measurement method involved specular light.