The optical system will always be different from the design value after been processed. It is necessary to adjust the relative positions between the optical elements to improve the imaging quality of the system. However, if the elements are adjusted randomly, the alignment will be inefficient, so the computer-aided alignment method came into being. In this article, for the alignment of large aberration systems, a new fully-connected network computer-aided alignment (Fc-Net CAA) method is proposed. The systems’ wavefront errors (WFEs) are described by the Zernike polynomials which have a huge advantage in describing system aberrations and we proposed a Fc-Net model for predicting systems’ misalignment. The Fc-Net model is trained with the WFEs of thousands of randomly misaligned instances of the lens system that are modeled in the optical design software, so as to establish the relationship between the system aberrations and the amount of misalignment. In this way, the proposed Fc-Net CAA can achieve the computer-aided adjustment process for systems with large aberrations without a complicated iterative process. The off-axis three-mirror system with aspheric surfaces was simulated and adjusted. During the simulation, a single round of adjustment can make the optical system close to the design wave aberration values, and the average of the five field-of-view WFEs is enhanced from 2.4λ (RMS; λ=550nm) to 0.0764 λ (average). The simulation results verify that the improved algorithm can solve the large initial alignment error of the offaxis reflective optical system with aspheric surfaces.
With the improvement of optical lens manufacturing and processing capabilities, the surface shape of optical components is becoming more and more complex, such as asymmetric double-sided off-axis aspheric lenses. Generally, people use two different surface detection equipment to detect this type of optical surface, which is inefficient and not universal. Thus in this paper, we present a dull Compensation method based on Spatial Light Modulator. In this method, we detected an asymmetric double-sided off-axis aspheric mirror with convex and concave surfaces with just one detection equipment. For the concave surface, the residual wave aberration is 0.0002λ (Peak to Valley), for the convex surface, the residual wave aberration is 0.0097λ (Peak to Valley). The result shows that this method is feasible in testing asymmetric double-sided off-axis aspheric lenses.
By combining optical systems and image processing, wavefront coding can greatly expand the depth of focus and depth of field of optical systems. It has been widely used in iris detection, high-power microscopic objective lens, infrared optical system athermalized, and so on. At present, the image restoration algorithms commonly used in wavefront coding are based on deconvolution, Wiener filtering, and so on. Although these algorithms can achieve an excellent image restoration effect, they will also bring boundary ringing effects and artifacts to the image. When the image is disturbed by strong noise, the restoration effect will also be seriously affected. To solve these problems, a wavefront coded image restoration algorithm based on compressed sensing is proposed in this paper. The strong data reconstruction ability of the compressed sensing restoration algorithm is used to restore the encoded image obtained by the wavefront coding system. This method can effectively suppress noise and reconstruct the image without artifact and boundary ringing effect. Through the comparison of simulation results, the effectiveness of the proposed method is verified.
With the development of miniaturization of smart devices, smart device imaging systems require lenses wit h extremely small size, optimal imaging quality and developability. The difficulty in the design of a small lens is how to design a lens with a longer focal length within the limit of the shorter total system length. The design should fit the optimal spatial resolution of the object while ensuring the maximum field of view, and on this basis, avoid large vision distortion caused by the field and other off-axis images. In this paper, a small lens for smart devices with a field of view of 68° and a total length of less than 5mm based on actual engineering is designed and the influence of lens length and lens focal length is analyzed. According to the needs of use, a design method combining spherical, aspheric and free -form surfaces is adopted. The spherical surface is made of glass, and the aspheric and free-form surfaces are molded by plastics, realizing a small lens design with processing feasibility and low cost. The lens will be combined with a focusing module and correction algorithm to be applied to micro intelligent instrument.
In order to collect detail information of the object in dim, the telescope image system need to be high-resolution and can gather enough power. These requires telescope image system with a large-diameter. Considering the load ability of the aircraft, there is also a strong demand for miniaturization and lightweight of the telescope system. Diffractive optical elements (DOEs) have great advantages in meeting these requirements. We designed two sets of telescope image systems with the same technical specifications. The primary mirrors of the two systems use traditional refractive lenses and DOEs respectively. By comparing the traditional refractive lenses and DOEs under the same focus and diameter, we demonstrate that DOEs have obvious advantages when it be applied in airborne optical systems with high requirements on volume and weight.
As a new Marine ecological disaster in the world, the inundation of jellyfish has seriously threatened the functions of Marine ecosystem. The body of jellyfish is mainly composed of water. It is composed of two layers, inner and outer. Between the two layers, there is a thick, transparent layer, which makes it difficult to detect jellyfish in the sea. In this article, sea jellyfish is realized by using the way of polarization imaging detection, setting the underwater imaging experiment device, using polarized light lighting actively, and using LED as light source. In the same time, the polaroid and wave plate experiments for different categories of polarized light, and a coaxial optical path to verify the polarization characteristics of background and target, to improve the image contrast. The polarization detector used in this paper can simultaneously image the polarization directions of 0°, 45°, 90° and 135°. In the experiment, four polarized images are fused, and the resulting image has a higher contrast ratio compared with the visible light intensity image and contains more detailed information.
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