Zoom Module Research Articles

Scaling of Three-Dimensional Computer-Generated Holograms with Layer-Based Shifted Fresnel Diffraction

Holographic three-dimensional (3D) displays can reconstruct a whole wavefront of a 3D scene and provide rich depth information for the human eyes. Computer-generated holographic techniques offer an efficient way for reconstructing holograms without complicated interference recording systems. In this work, we present a technique for generating 3D computer-generated holograms (CGHs) with scalable samplings, by using layer-based diffraction calculations. The 3D scene is partitioned into multiple layers according to its depth image. Shifted Fresnel diffraction is used for calculating the wave diffractions from the partitioned layers to the CGH plane with adjustable sampling rates, while maintaining the depth information. The algorithm provides an effective method for scaling 3D CGHs without an optical zoom module in the holographic display system. Experiments have been performed, demonstrating that the proposed method can reconstruct quality 3D images at different scale factors.

Bi-branch deconvolution-based convolutional neural network for image classification

With the rise of deep neural network, convolutional neural networks show superior performances on many different computer vision recognition tasks. The convolution is used as one of the most efficient ways for extracting the details features of an image, while the deconvolution is mostly used for semantic segmentation and significance detection to obtain the contour information of the image and rarely used for image classification. In this paper, we propose a novel network named bi-branch deconvolution-based convolutional neural network (BB-deconvNet), which is constructed by mainly stacking a proposed simple module named Zoom. The Zoom module has two branches to extract multi-scale features from the same feature map. Especially, the deconvolution is borrowed to one of the branches, which can provide distinct features differently from regular convolution through the zoom of learned feature maps. To verify the effectiveness of the proposed network, we conduct several experiments on three object classification benchmarks (CIFAR-10, CIFAR-100, SVHN). The BB-deconvNet shows encouraging performances compared with other state-of-the-art deep CNNs.

Active optical zoom system.

In this work, we propose an active optical zoom system. The zoom module of the system is formed by a liquid lens and a spatial light modulator (SLM). By controlling the focal lengths of the liquid lens and the encoded digital lens on the SLM panel, we can change the magnification of an image without mechanical moving parts and keep the output plane stationary. The magnification can change from 1/3 to 3/2 as the focal length of the encoded lens on the SLM changes from infinity to 24cm. The proposed active zoom system is simple and flexible, and has widespread application in optical communications, imaging systems, and displays.

Optical zoom camera module using two poly-dimethylsiloxane deformable mirrors.

Miniaturization is an essential trend in the design of portable devices. Motor-driven lens technology is a traditional way to achieve autofocus and optical zoom functions. This approach usually requires considerable space and consumes significant power. Reflective optics is a methodology that not only can fold the optical path, but it has the advantage of low chromatic aberration. In this paper, we use a deformable mirror as a reflecting element in an optical zoom system. For its low Young's modulus and residual stress, we choose polydimethylsiloxane as a deformable membrane that can provide a large stroke. The optical zoom module consists of a pair of micromachined deformable mirrors. The thickness of this module is 10 mm, which enables 2× optical zoom. The smallest effective focal length is 4.7 mm at a full field angle of 52°, and the f-number is 4.4. The largest effective focal length of the module is 9.4 mm, and the f-number is 6.4.

Optical zoom module based on two deformable mirrors for mobile device applications

In recent years, optical zoom functionality in mobile devices has been studied. Traditional zoom systems use motors to change separation of lenses to achieve the zoom function, but these systems result in long total length and high power consumption, which are not suitable for mobile devices. Adopting micromachined polymer deformable mirrors in zoom systems has the potential to reduce thickness and chromatic aberration. In this paper, we propose a 2× continuous optical zoom system with five-megapixel image sensors by using two deformable mirrors. In our design, the thickness of the zoom system is about 11 mm. The effective focal length ranges from 4.7 mm at a field angle of 52° to 9.4 mm. The f-number is 4.4 and 6.4 at the wide-angle and telephoto end, respectively.

Experimental analysis on barrel zoom module of digital camera for noise source identification and noise reduction

Noise of digital camera has been noticeable to its users. Particularly, noise of a barrel assembly module in zoom in/zoom out operation is recorded while taking a video. Reduction of barrel noise becomes crucial but there are not many studies on noise of digital camera due to its short history of use. In this study, experiment-based analyses are implemented to identify sources of noise and vibration because of complexity and compactness of the barrel system. Output noise is acquired in various operation conditions using synchronization for spectral analysis. Noise sources of a barrel assembly in zoom operating are first identified by the comparison with gear frequency analysis and then correlation analysis between noise and vibration is applied to confirm the generation path of noise. Analysis on noise transfer characteristic of zoom module is also carried out in order to identify the most contributing components. One of possible countermeasures of noise in zoom operating is investigated by an experimental approach

실험적 방법을 이용한 디지털 카메라 경통 줌 모듈의 소음원 규명 및 저소음화

Noise of digital camera has been noticeable to its users. Particularly, noise of a barrel assembly module in zoom in/zoom out operation is recorded while taking a video. Reduction of barrel noise becomes crucial but there are not many studies on noise of digital camera due to its short history of use. In this study, experiment-based analyses are implemented to identify sources of noise and vibration because of complexity and compactness of the barrel system. Output noise is acquired in various operation conditions using synchronization for spectral analysis. Noise sources of a barrel assembly in zoom operating are first identified by the comparison with gear frequency analysis and then correlation analysis between noise and vibration is applied to confirm the generation path of noise. Analysis on noise transfer characteristic of zoom module is also carried out in order to identify the most contributing components. One of possible countermeasures of noise in zoom operating is investigated by an experimental approach.

Three-dimensional illumination system using dielectric liquid lenses

A 25-pixel illumination system composed of a 5 × 5 dielectric liquid-lens (DLL) zoom module array, 25 light-emission diodes (LEDs), and a secondary optical lens demonstrates 3D light field manipulation. LEDs function as 2D illumination pixels while the DLL module array performs longitudinal illuminance adjustability by zooming each illumination pixel. A test on the similarity of two illuminance patterns between experiments and simulations shows a normalized cross correlation (NCC) higher than 0.8, indicating the feasibility of the system design. Also, the illumination system is further applied to correct a distorted light pattern on a 45° tilt screen as well as to perform light compensation on distance-differential objects.

Design and Analyses of a Planar Zoom Module as a Beam Expander

A novel planar zoom module (PZM) is presented in this article. The PZM is realized by integrating optical elements on its surfaces with the folding optical axis and performing the zoom function by transversal rotation or motion. Its application as a multimagnification beam expander is designed, analyzed, and demonstrated.