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Large aperture, lightweight optics are frequently utilized in modern optical systems. However, despite the use of advanced techniques for developing their materials, fabrication, and mechanical structure, the coatings placed on the substrates induce slight lattice mismatches and increase the thin film stress on polished surfaces. This significantly distorts nano-accuracy optical surfaces, especially on lightweight freeform surfaces. In this study, we construct a finite element model (FEM) and a ray tracing model to estimate the impact of the stress-induced deformation of the coating on a 1.5m class lightweight silicon carbine (SiC) mirror with a freeform surface. Our simulation results are within 10% deviation from the experimental results, and the deformation texture map matches these results as well. We discuss several possible strategies to overcome stress-induced deformation, including fabrication pre-compensation, lightweight structure redesign, and an inverse print-through effect.

Spectral imaging technique, which retrieves both spatial and spectral information of a scene or an object, is an important tool in applications such as food inspection, vegetation monitoring and geographic remote sensing. Most spectral imaging systems have a complex system architecture, in which different components are used for different functions, limiting the efficiency of information retrieval. Here, we propose a hyperspectral imaging system with a simple architecture, where a multiplexing digital micromirror device functions both as a spatial light modulator for spatial imaging and a diffractive grating for spectral measuring simultaneously. The proof-of-principle system contains a group of lenses, a digital micromirror device and a one-dimensional detector array, and is capable of performing 128 × 128 pixel resolution hyperspectral imaging over the visible spectrum with an experimental 3.73 nm spectral resolution. Furthermore, by using a compressive sampling strategy, continuous real-time spectral video is performed with a frame-rate up to 10 Hz. The concise architecture of the proposed system, with the potential to be easily extended to both ultraviolet and infrared, offers an alternative scheme to manufacture low-cost, compact, hyperspectral imagers.

The ptychographic iterative engine (PIE) is an algorithm for coherent lens-less diffraction imaging. It facilitates the development of low-cost large field of view (FOV) lens-less microscopy, as it can expand the FOV extensively by moving the light source or the bio-medical pathological sample slide. In a PIE setup, the illumination light needs to have high/partially coherence. Thus, to get a colorful microscopy image, more than 3 illumination light sources with different dominant wavelengths are required in a traditional PIE setup. In this manuscript, an improved PIE based on computational deep learning color-transferring method is proposed to achieve colorful large FOV lens-less microscopy imaging. In our method, only one high/partially coherent light source is used, where the image data are three times less than those images under multiple illuminations for colorful PIE microscopy. It is believable that our colorful PIE microscopy enhanced by the deep color-transferring method would be helpful for the development of low-cost large FOV lens-less microscopes.

Amounts of cost-effective biological observing and detecting instruments are needed in biology and medical applications. In these demands, a low-cost, portable microscope with light-weight and tele-communication, is very attractive in the resource-limit area. In this manuscript, a portable singlet phase contrast microscope based on smart-phones are proposed. In the optics hardware, an external singlet lens is designed and closely attached before the rear cameras of a smart-phone, which constructs the imaging part of a simplified microscope. And a circular oblique illumination is adopted. In the computational imaging part, the in-focus images recorded by the smart-phone are virtually enhanced and style-transferred to phase contrast images by deep learning methods. Through pairs of experimental image data, we train the deep learning network and demonstrate the effectiveness of this virtual phase contrast imaging approach using multiple samples, e.g., unstained/transparent tumor tissue pathological slide, and H&E (Hematoxylin and Eosin) stained tumor tissue pathological slide. Our results provide a powerful example of low-cost portable phase contrast microscope with high-speed tele-communication abilities in the 5G + mobile internet era.

Singlet microscopy is very attractive for the development of cost-effective and portable microscopes. In contrast to conventional microscope objectives, which consist of multiple lenses, the manufacturing process for singlet lenses is done without extensive assembling and aligning. In this manuscript, we report a novel singlet virtual Zernike phase contrast microscopy setup for unstained pathological tumor tissue slides. In this setup, the objective consists of only one lens. There is no need for the inset Zernike phase plate, which is even more expensive than a whole brightfield microscopy setup. The Zernike phase contrast is virtually achieved by the deep learning computational imaging method. For the practical virtual Zernike phase contrast microscopy setup, the computational time is less than 100 ms, which is far less than that of other computational quantitative phase imaging algorithms. With a conceptual demo experimental setup, we proved our proposed method to be competitive with a research-level conventional Zernike phase contrast microscope and effective for the unstained transparent pathological tumor tissue slides. It is believed that our deep learning singlet virtual phase contrast microscopy is potential for the development of low-cost and portable microscopes and benefits resource-limited areas.

Ion beam figuring(IBF) is commonly used during the process of fine optical fabrication. According to sputtering theory, material removal rate varies with the ion inject angle and the surface curvature. During the process of figuring high gradient aspherical surface, the removal function of ion beam figuring should be calibrated strictly to guarantee the accuracy of the figuring results. In this paper, we describe the influence of ion density distribution and surface curvature on material removal rate. Since the removal function varies from point to point within the ion bombed region for high gradient surface, rectification matrix was proposed to fix the disparity between the practical removal function and flat removal function. Experiments were implemented with high gradient aspherical surface to prove the rectification matrix can fit the variety of the material removal rate effectively.

Ion beam figuring technology is ultra-high precision optical processing method. This paper introduces the independent FSGJ800-IBF five axis ion beam figuring equipment. According to the requirement of ion beam motion system dynamic performance of complex optical surface ion beam figuring, the design and control scheme of 3-RPS+XY mobile platform based on hybrid mechanism form five axis motion system was finished. Firstly, the radio frequency (RF) ion beam source was use in this machine. The Ion Beam Figuring System with Five-Axis Hybrid Mechanism was introduced especially the 3-RPS parallel mechanism. The process of polishing complex optical curved surface by ion beam is analyzed. The most close to the spherical surface processing strategy based on the experiments of high gradient lens was done. The aperture of the lens is 44mm and the R/# is 0.705, after a round of ion beam polishing, surface error of optical components RMS from the initial 0.019 lambda (lambda =632.8nm) converges to 0.006 lambda. The experiments verified the availability of the Five-Axis Hybrid Mechanism for high precision complex optical surface error correction.

The phase type computer generated hologram (CGH) plays an important role in aspherical surface optical testing, especially for low reflectivity material mirror surfaces, owing to its high diffractive efficiency. With the increasing demand for high precision CGHs, traditional methods such as reactive ion etching and focusing ion beam, have difficulty realizing the fabrication of a large aperture and high accuracy phase type CGH. In this study, fabrication of a high precision CGH has been demonstrated via a new method called scanning ion beam etching (SIBE), which is suitable for most common optical materials and the fabrication of high performance CGH. On the basis of the movable radio frequency ion source, we determine an etching depth calculation method to realize high accuracy etching regardless of whether the removal function is a perfect Gaussian distribution. Experiments are conducted to verify the etching depth accuracy. Moreover, the linewidth, sidewall angle, roughness, and etching uniformity results of the CGH are superior to the fabrication of CGH via the conventional method. As a proof of concept, a phase type CGH with an aperture of 80 mm is fabricated, and the wavefront accuracy is 6.2 nm, which can meet the processing requirements of a high precision aspheric mirror. Thus, a SIBE method is developed for high performance CGH, which may aid in the development of high accuracy diffractive optics.

Singlet lenses are free from precise assembling, aligning, and testing, which are helpful for the development of portable and low-cost microscopes. However, balancing the spectrum dispersion or chromatic aberrations using a singlet lens made of one material is difficult. Here, a novel method combining singlet lens microscopy and computational imaging, which is based on deep learning image-style-transfer algorithms, is proposed to overcome this problem in clinical pathological slide microscopy. In this manuscript, a singlet aspheric lens is used, which has a high cut-off frequency and linear signal properties. Enhanced by a trained deep learning network, it is easy to transfer the monochromatic gray-scale microscopy picture to a colorful microscopy picture, with only one single-shot recording by a monochromatic CMOS image sensor. By experiments, data analysis, and discussions, it is proved that our proposed virtual colorization microscope imaging method is effective for H&E stained tumor tissue slides in singlet microscopy. It is believable that the computational virtual colorization method for singlet microscopes would promote the low-cost and portable singlet microscopy development in medical pathological label staining observing (e.g., H&E staining, Gram staining, and fluorescent labeling) biomedical research.

Anisotropic conductive films (ACFs) are of great significance in miniaturized sensing devices, however it still is a huge challenge to fabricate ACFs via a facile and cost-effective method. Herein, ACFs containing aligned conductive stripes have been developed based on polypropylene (PP)/multi-walled carbon nanotubes (MWCNTs) composite. Compared with their isotropic counterparts, they demonstrate quick response, high responsivity and excellent reversibility for volatile organic vapors. The maximum responsivity toward three organic vapors is in the order of cyclohexane > dichloromethane > ethyl acetate, which is consistent with the calculated Flory-Huggins interaction parameter. The superior organic vapor sensing behavior of anisotropic PP/MWCNTs film (A-P/M-F) can be ascribed to the clear interfaces between stripes, which can accelerate the rapid absorption/desorption of vapors at such interfaces. Moreover, the spatial confining forced effect between the neighboring stripes is beneficial for reconstructing and stabilizing the internal conductive network, endowing A-P/M-F containing aligned conductive stripes with a good sensing stability. Furthermore, their vapor sensing behavior shows temperature dependence, that is, it increases with the increasing temperature because of higher absorption activation energy at higher temperature. This work provides a facile but cost-effective way to fabricate ACFs, enabling its industrial-scale application as organic vapor sensor with high stability and satisfied reliability.

Ion beam figuring (IBF) is a deterministic method for final figuring process of optical surface. The removal functions of IBF should be measured and calibrated strictly to guarantee the accuracy of the figuring results. The incident parameters of ion, surface profile and ion density distribution on the surface are the main factors which affect the material removal rate within the removal function. For the curved surfaces these factors vary from point to point so that the removal functions keeps changing when figuring curved surface especially for steep surface. Unlike the first two factors, the ion density distribution can’t be described by mathematic expression directly. Moreover, the ion is not in Gaussian distribution on the curved surface any more, which will result in variation of removal functions. Faraday cup is used to get the ion space distribution. So that the ion density on an arbitrary point can be obtained exactly. Based on the material removal features, revision method is proposed to fix the difference of the removal functions between the curved surface and the flat surface. Through experiments and theoretical analysis, the removal functions changes distinctly and not in Gaussian distribution. The computation method can fit the variety of the removal function effectively.

Ion beam figuring (IBF) is an advanced and deterministic method for optical mirror surface processing. The removal function of IBF varies with the different incident angles of ion beam. Therefore, for the curved surface especially the highly steep one, the Ion Beam Source (IBS) should be equipped with 5-axis machining capability to remove the material along the normal direction of the mirror surface, so as to ensure the stability of the removal function. Based on the 3-RPS parallel mechanism and two dimensional displacement platform, a new type of 5-axis hybrid machine tool for IBF is presented. With the hybrid machine tool, the figuring process of a highly steep fused silica spherical mirror is introduced. The R/# of the mirror is 0.96 and the aperture is 104mm. The figuring result shows that, PV value of the mirror surface error is converged from 121.1nm to32.3nm, and RMS value 23.6nm to 3.4nm.

The thin mirrors are widely used in active optical system. In this letter, magnetic medium assistant polishing (MMAP) technology and device are discussed for thin mirrors optical finishing. The principle of MMAP is introduced, the magnetic tool for polishing is designed, and the removal function of magnetic polishing tool is studied. On the basis study of the material removal function especially removal property in the edge region, the tool-path is optimized, and the dwell time distribution of computer-controlled MMAP is researched. The glass thin mirror is polished by MMAP technology. The diameter of the work-piece equals S22201 150 mm and the thickness is 5 mm. The initial surface error is 0.19\lambda (root mean square (RMS)) , and after two steps fabrication, the final surface error reaches 0.02\lambda. The experimental rsults verify that the technology is effective for thin mirrors finishing.

The high precision off-axis asphere mirrors are quite usefull in the modern sapce optical system.in this paper, the ion beam figuring is researched to accomplish the final surface accuracy. Firstly, The IBF machine we used is introduced simplely. The correction method for the distortion in off-axis mirror interference measurement is studied. Beacasue of the curve shape of the off-axis mirror, the changing of the removal function was analyzed simply. In order to testify the reaserch, a 1100mm×800mm off-axis aspheric mirror is finished by ion beam figuring. After 2 times polishing, the surface error was corrected to RMS 9nm in full aperture and achieved 6.3nm in sub- aperture.

In this paper, a Gabor filter optimization method based on real-coded genetic algorithm is presented for iris recognition. First, we list Gabor filter parameters and analyzed the validity of the expression for texture features. Then, since Gabor parameters has a great influence in Correct Recognition Rate, we took Gabor kernel parameters as chromosomes and Discriminative Index as fitness to on the CASIA V3 and JLUBR-IRIS for optimization. Moreover, the optimized Gabor filters are adopted to extract features for corresponding iris databases, which can obtain excellent results.

During the ion beam figuring (IBF) of a space mirror, thermal radiation of the neutral filament and particle collisions will heat the mirror. The adhesive layer used to bond the metal parts and the mirror is very sensitive to temperature rise. When the temperature exceeds the designed value, the mirror surface shape will change markedly because of the thermal deformation and stress release of the adhesive layer, thereby reducing the IBF accuracy. To suppress the thermal effect, we analyzed the heat generation mechanism. By using thermal radiation theory, we established a thermal radiation model of the neutral filament. Additionally, we acquired a surface-type Gaussian heat source model of the ion beam sputtering based on the removal function and Faraday scan result. Using the finite-element-method software ABAQUS, we developed a method that can simulate the thermal effect of the IBF for the full path and all dwell times. Based on the thermal model, which was experimentally confirmed, we simulated the thermal effects for a 675 mm×374 mm rectangular SiC space mirror. By optimizing the dwell time distribution, the peak temperature value of the adhesive layer during the figuring process was reduced under the designed value. After one round of figuring, the RMS value of the surface error changed from 0.094 to 0.015λ (λ=632.8 nm), which proved the effectiveness of the thermal analysis and suppression method.

A new method combined subaperture stitching with interferometry(SSI) is introduced. It can test large and off-axis aspheric surfaces without the aid of other null optics. In this paper the basic principle and theory of the technique are analyzed. The synthetical optimization stitching model and effective stitching algorithm are established based on homogeneous coordinates transformation and simultaneous least-squares method. The software of SSI is devised and the prototype for testing of large aspheres by SSI is designed and developed. An off-axis asphere with the aperture of 376mm×188mm is tested by this method. For comparison and validation, the asphere is also tested by null compensation.The synthesized surface profile is consistent to that ofthe entire surface from null test; and the difference of PV and RMS error between them is 0.047 λ and 0.006 λ, respectively. So it provides another quantitative measurement for testing large aspheric surfaces and off-axis aspheres besides null-compensation.

It is a key point of CO2 laser beam monitoring in the CO2 laser processing system to achieve alignment between CO2 laser and PL (pointing and launching) system. By monitoring the angle offset of CO2 laser beam, the compensation can be gotten witch is given to fast-steering mirror to rectify the direction of laser beam. But the normal photoelectric detector can not get the laser signal because of CO2 laser's high energy and long wavelength. Its wavelength is 10.6μm and its power can reach kW level. Consequently, it is difficult to detect the high-energy 10.6μm laser beam directly. So, we monitored the output mirror of laser resonator superseded the laser beam, indirectly. The laser beam monitoring system could be designed based on CCD laser auto-collimation angular measurement principle and image processing method. In this paper, application of CCD laser auto-collimation angular measurement principle and image processing method for CO2 laser beam monitoring system is introduced particularly, After design, fabrication and alignment, the monitoring system can be used for experimental study that including angular measurement accuracy and angle offset measurement of CO2 laser beam. Angle offset range and angle variation rule of CO2 laser beam is also can be acquired for further research.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Annular subaperture stitching interferometric technology can test large-aperture, high numerical aperture aspheric surfaces with high resolution, low cost and high efficiency without auxiliary null optics. In this paper, the basic principle and theory of the stitching method are introduced, the reasonable mathematical model and effective splicing algorithm are established based on simultaneous least-squares method and Zernike polynomial fitting. The translation errors are eliminated from each subaperture through the synthetical optimization stitching mode, it keeps the error from transmitting and accumulating. The numerical simulations have been carried on by this method. As results, the surface map of the full aperture after stitching is consistent to the input surface map, the difference of PV error and RMS error between them is -0.0074 λ and -0.00052 λ (λ is 632.8nm), respectively; the relative error of PV and RMS is -0.53% and -0.31%; and the PV and RMS of residual error of the full aperture phase distribution is 0.027 λ and 0.0023 λ, respectively. The results conclude that this splicing model and algorithm are accurate and feasible. So it provides another quantitive measurement for test aspheric surfaces especially for large aperture aspheres besides null-compensation.

Silicon (Si) modification layer on silicon carbide (SiC) surface is widely used in space optical systems. To achieve high-quality optical surface, the technology of ion beam figuring (IBF) is studied. The radio frequency ion beam source is introduced briefly. Then the removal function experiment is studied. The volume removal stability of the IBF reached 97% in 10 h continuous working testing. The parameters of the IBF removal function are calculated by Gaussian fitting including the removal rate and the full-width half-maximum. Then the removal function results are used in practical fabrication. The workpiece is a plane with Si modification layer on SiC surface. After 148 min processing IBF, the final surface error reaches 1.2 nm RMS.