The acquisition of sharp, full-focus images and the restoration of microscopic scenes require complex instrumentation and algorithms. To conveniently obtain the three-dimensional (3-D) structural information of full-focus images and high-quality microscopic scenes, we construct a zoomable 3-D microscope imaging system and propose new image fusion and depth reconstruction algorithms based on this imaging system. The image acquisition environment of the system is analyzed using interference factors such as light transmission variation and jitter, and the corresponding image preprocessing methods are discussed. We combined the new sum-modified-Laplacian (SML) and local band-limited contrast methods, which contain multiple image features but measure the image definition from different angles, then proposed a mixed-contrast factor, and combined it with the SML method to propose an image fusion method. We then proposed a depth reconstruction method based on the structural similarity of multifocus images. For cases where depth reconstruction results in large distortion with high noise, we proposed a depth value restoration method based on anisotropic diffusion to improve the 3-D reconstruction results. Experimental results show that the proposed image fusion and depth reconstruction methods exhibit excellent performance.
An extended depth-of-field projection is needed for spatial augmented reality. However, conventional projectors are often designed with a small F/#, which causes a narrow depth-of-field. This paper presents a new system consisting of a variable focus optical path and 1000-fps 8-bit high-speed projector. This system oscillates the focal length of the lens at high speed and synchronizes it with the projection. High speed performance contributes to project clear images even under the oscillated focal length and to realize all-in-focus projections on more than 10 targets at different depths.
To capture an all-in-focus and 3D depth image, shape from focus method is widely used. The phase accuracy of the image candidates should be processed and adjusted beforehand. Phase only correction method was employed in this work and to accelerate the processing speed, the image processing by Fast Fourier Transform (FFT) was optimized. Meanwhile, the processing task was assigned in several parallel threads so that the performance would be improved. The method was used on a variable focus imaging system, and, as a result, the processing speed was improved to around 2.5-fps.
It is a challenge for conventional projectors to conduct projection mapping for a 3D dynamic moving object along the depth direction, due to the limitation of their narrow depth-of-field. Here, a dynamic projection system is proposed that has overcome the above limitation by employing a liquid-filled variable focal unit and a depth-sensing module. The depth sensor detected the depth information of the projection target, and then served as feedback to adjust the focal length of the variable focal lens, in turn, the focal length of the projection system would be controlled. A well-focused projection mapping with a randomly moving object would be demonstrated.
With the purpose of designing a liquid-filled variable focus lens with a large optical aperture and high-speed performance, an investigation research and a series of comparison experiments were conducted. One of the foundings is that the eigenfrequencies of the actuation unit and the lens' dynamic surface profile will become the critical parameters when the lens aperture becomes large. Mechanics analysis of the deformation was studied, and a series of the lens prototype was built.
Microscopy imaging optics can capture the high-resolution image at a certain focus plane, but the information outside that focal plane will become a blur and the information will be lost. We can adjust the optics stop or manually adjust the focal length, but the resolution will be reduced and it is capable of observing a high speed moving target in vivo. When a transparent plate was placed in front of a camera, the focusing point of the original system would be shifted. We proposed a variable focus system for extending the depth of field of the microscopy imaging system.
We report a novel method to manipulate the direction of a laser beam by controlling the thickness of a dielectric elastomer. The system is controlled by applying different voltages to multi-layers of dielectric elastomers without mechanical movement. We employed laser beams with different wavelengths to test the proposed system, and the experimental results showed that it has an excellent transmittance profile in the ultraviolet and visible wavelength bands, and that we achieved high-precision control in the micrometer range. The results show the feasibility of this technique for laser applications that require high positional accuracy, such as laser cutting, drilling machines, and 3D printing.
An adaptive chromatic doublet that designed by doublet variable focus lenses was proposed. Two lenses were in filled with different liquids, so that the lenses could perform low and high dispersion proprieties. The proposed doublet could performance a tunable focal length, and meanwhile its chromatic aberration could be corrected. Four available liquids candidates were proposed to fabricate two variable focus lenses that would be designed with liquid-membrane-liquid structure, so that they could realize a large aperture adaptive achromatic doublet. The improvement of the achromatic behaviors was confirmed that the chromatic focal shift range was 2.5% for the adaptive singlet and 0.05% for the adaptive doublet.
We describe and demonstrate a pair of diopter-adjustable eyeglasses aimed to correct presbyopia; the glasses provide a tunable optical power in the whole surface of the lens cell, eliminating the optical distortion typical of bifocal/trifocal or progressive glasses. The wearer can actively control the optical power by a simple sliding gesture on the bridge of the glasses, so that presbyopic vision can be interactively corrected. Results from a preliminary experiment showed that a presbyopia sufferer could clearly observe near and far objects under the assistant accommodation of the glasses. Designing a truly wearable system poses some challenges – none of them theoretical – so the system should be feasible in the near future.
With the purpose of designing a variable-focal lens with large optical aperture, a liquid lens with liquid-membrane-liquid
structure and 30mm optical aperture is proposed. Function of the inserted membrane is stated that much stronger elastic
force takes place of interface tension, and enlarging aperture size of liquid lens becomes possible. Mechanics analysis of
membrane’s deformation and finite element simulation was employed to demonstrate the elastic force maintains the
deformation into a parabolic shape. Moreover, a prototype lens was designed and optical performance with a refractive
power range of 7.7Diopters, and 7.13line-pair/mm resolution was measured in experiments.