A thermal imaging system has been demonstrated, which uses wavefront coding to provide an extended depth of field. Aberrations are introduced into the optical system, which are optimised to be insensitive to defocus;a...
详细信息
ISBN:
(纸本)9780819483522
A thermal imaging system has been demonstrated, which uses wavefront coding to provide an extended depth of field. Aberrations are introduced into the optical system, which are optimised to be insensitive to defocus;a single image processing algorithm can be successfully applied to images with a range of focus errors. This requires both the design of the wavefront coding surface and the implementation of efficient and effective image processing electronics. The design of the freeform wavefront coding surface goes hand-in-hand with that of the electronics architecture. An optimised decoding algorithm is implemented in the image processing electronics to achieve real-time imaging performance.
In the domain of reconnaissance, remote sensing, etc., people want to get high resolution images. There is a conflict between the resolution and the optical system defocus. In order to acquire high resolution images, ...
详细信息
ISBN:
(纸本)9781424410910
In the domain of reconnaissance, remote sensing, etc., people want to get high resolution images. There is a conflict between the resolution and the optical system defocus. In order to acquire high resolution images, some methods are taken to minish the defocus, but these ways affect the cost and weight of the system. In this paper, a novel technology was described for extending the depth of focus of the incoherent optical system;meanwhile this technology does not decrease the resolution of the images. In this technology, the aspheric optical element is used to encode the images as well as the digital signal processing is used to decode the images. It is significant for optical remote sensors to acquire high resolution images under complicated space environment.
Aiming at the problems of traditional wavefront coding system, such as single phase mask (modulation) and limited extended depth of field, a wavefront coding imaging system using deformable mirror (DM) is proposed to ...
详细信息
ISBN:
(纸本)9781510656970;9781510656963
Aiming at the problems of traditional wavefront coding system, such as single phase mask (modulation) and limited extended depth of field, a wavefront coding imaging system using deformable mirror (DM) is proposed to realize dynamic coding. In this paper, continuous pure phase coding based on Zernike polynomial is designed by the simulated annealing algorithm for different defocus distances, with the aim of thus getting the most suitable coding strength for different defocus distance. And in the decoding process, the PSF of the defocused position corresponding to the blurred image is used for restoration, which reduces the artifacts caused by using the PSF of the focal position to restore all the defocused images. The experiment shows that compared with the traditional fixed phase mask, the wavefront coding imaging system of DM can achieve dynamic coding and decoding, which increases the imaging flexibility of the wavefront coding system and improves the quality of the decoded image.
The quality of X-ray optics on beamline is a key factor that limits the performance of the beam line to play. For X-ray mirror surface characterization with high accuracy, long trace profiler and NOM for flat or sligh...
详细信息
ISBN:
(纸本)9781628419221
The quality of X-ray optics on beamline is a key factor that limits the performance of the beam line to play. For X-ray mirror surface characterization with high accuracy, long trace profiler and NOM for flat or slight curved mirror have been developed. However, these two kind of instruments cannot measure the highly curved mirror since requirement of high precision and that of large range contradict each other. In this paper, we proposed a novel wavefront-coding-based surface slope metrology technique. Four-dimension information of the optics under test, including x-y position and sagittal/tangential angle, is provided. Due to the focused beam used and the high speed DMD (Digital Mirror Device), high spatial resolution of the measurement is obtained. In experiment, we demonstrated this technique by measuring bend-based high energy monochromator developed in BSRF.
作者：
Chen, XinhuaWang, XiaofengShen, WeiminSoochow Univ
Coll Phys Optoelect & Energy Suzhou 215006 Peoples R China Soochow Univ
Key Lab Adv Opt Mfg Technol Jiangsu Prov Educ Minist China Suzhou 215006 Peoples R China Soochow Univ
Key Lab Modern Opt Technol Educ Minist China Suzhou 215006 Peoples R China
The Strehl ratio (SR) describes the ratio of the on-axis intensity between the aberrated system and the diffraction limited system. It can be used to build the merit function for the optimization of phase mask in the ...
详细信息
ISBN:
(数字)9781510622005
ISBN:
(纸本)9781510622005
The Strehl ratio (SR) describes the ratio of the on-axis intensity between the aberrated system and the diffraction limited system. It can be used to build the merit function for the optimization of phase mask in the wavefront coding system. We propose a computationally efficient method for the SR and use it to compute the SR with different defocus errors for the wavefront coding system using the rotationally symmetric phase mask. With this method, the computation efficiency of the merit function can be improved greatly in the optimization of the rotationally symmetric phase mask.
The wavefront coding technology is known as a system-level technology which can extend the depth of focus of optical system by innovative optical design and image restoration. This technology can control misfocus rela...
详细信息
ISBN:
(纸本)9780819472885
The wavefront coding technology is known as a system-level technology which can extend the depth of focus of optical system by innovative optical design and image restoration. This technology can control misfocus related aberrations including misfocus, astigmatism, and Petzval curvature, temperature-related misfocus in digital imaging systems. It can also help optical system tolerate more residual error in optical manufacturing and alignment besides misfocus. The brief introduction of wavefront coding technology and the wavefront coded TMA system under research is presented respectively in part I and part 2. The "MTF similarity" is defined to describe the relationship among MTF at different position or different fields in the third part. It is also shown in this part that the MTF similarity of wavefront coded system is much higher than the normal system within a large range. In part 4 comparison between the origin system and the new system with wavefront coding technology is provided after multiple errors are introduced, from which it can be observed that the system with wavefront coding technology can tolerate much bigger error than origin system. The error tolerance is re-distributed according to a new criterion based on MTF similarity. If the MTF similarity is less than a certain value, it can be regarded that the system can tolerate the residual error. The new error tolerance is displayed and it is shown that the wavefront coding technology can also loosen the error distributing besides extended the depth of focus.
A compound eye optical system design allows us to construct a compact image scanner with a large field of view and a large depth of field, both of which are beneficial for use in a copier's flatbed scanner. Our pr...
详细信息
A compound eye optical system design allows us to construct a compact image scanner with a large field of view and a large depth of field, both of which are beneficial for use in a copier's flatbed scanner. Our prototypes are constructed of 32 or 28 imaging units, which are ommatidia, and the representations from the imaging units are electrically combined. Since the arrangement of the imaging units is a key factor in combining the images correctly without any loss at the boundaries, we discuss two types of arrangements along with results of their prototypes: a one-line arrangement of varying magnification imaging units and a two-line staggered arrangement of telecentric imaging units. We also discuss the effectiveness of wavefront coding (WFC) in suppressing chromatic aberration, which is caused using cheap refractive imaging units, along with experimental results of applying both cubic- and quartic-phase-modulated WFC. (C) The Authors.
Freeform surfaces are being developed for number of applications like illumination systems, compact projection systems, head up display, ophthalmic and automotive industries. One of the important use of such surfaces ...
详细信息
Freeform surfaces are being developed for number of applications like illumination systems, compact projection systems, head up display, ophthalmic and automotive industries. One of the important use of such surfaces in optical imaging application is wavefront coding for large depth of focus camera. The thermal induced defocus is the well-known problem in infrared (IR) imaging systems. The efficient technique to mitigate the effect of defocus is wavefront coding, The phase profile for wavefront coding application with IR camera is a cubic freeform profile, that enables the focus invariant across the region near the focal plane. This work presents the development of a high precision cubic freeform profile on Germanium (Ge) substrate and its application for extended depth of focus for IR imaging camera. The cubic freeform profile on the surface is generated using single point diamond turning (SPDT) in slow tool servo (STS) configuration. It is further polished by using bonnet polisher with polyurethane and uninap-13 pads in seven axis polishing machine. The precise work piece alignment during the generation and characterization of the surface is very important aspect which is taken care by introducing fiducials from the beginning of the process of realization of the component. Full field measure-ment of grinded surface is carried out by using long wavelength interferometer. Computer generated hologram (CGH) in Fizeau interferometer is used for corrective polishing metrology and final testing of the surface profile. Precise work piece alignment and full field measurement starting from the grinding stage helped to achieve surface with residual error of 0.2 mu m PV and 1.4 nm RMS roughness (Rq). The developed cubic profile is used in infrared camera for wavefront coding in an experimental setup for the verification of the intended results.
In our previous published paper [Opt. Commun. 490, 126876 (2021)], we proposed a method to correct the optical dome's aero-optical aberration using wavefront coding (WFC). The simulation results were carried out u...
详细信息
In our previous published paper [Opt. Commun. 490, 126876 (2021)], we proposed a method to correct the optical dome's aero-optical aberration using wavefront coding (WFC). The simulation results were carried out under a fixed flight altitude. However, because the missile tracking the target is a dynamic process, the image quality deterioration of the aero-dynamically heated dome is diverse under different altitude. Therefore, it is of great significance to study the correction effect of WFC on dynamic aero-optical aberration of optical dome at different altitudes, which is performed in our new manuscript. The simulation results demonstrate that the WFC could effectively correct the dynamic aero-optical aberration and improve the accuracy of imaging guidance. These results confirm the possibility of the application of WFC imaging technology in missile-borne optical detection systems.
The image deconvolution technique can recover potential sharp images from blurred images affected by aberrations. Obtaining the point spread function (PSF) of the imaging system accurately is a prerequisite for robust...
详细信息
The image deconvolution technique can recover potential sharp images from blurred images affected by aberrations. Obtaining the point spread function (PSF) of the imaging system accurately is a prerequisite for robust deconvolution. In this paper, a computational imaging method based on wavefront coding is proposed to reconstruct the wavefront aberration of a photographic system. Firstly, a group of images affected by local aberration is obtained by applying wavefront coding on the optical system's spectral plane. Then, the PSF is recovered accurately by pupil function synthesis, and finally, the aberration-affected images are recovered by image deconvolution. After aberration correction, the image's coefficient of variation and mean relative deviation are improved by 60% and 30%, respectively, and the image can reach the limit of resolution of the sensor, as proved by the resolution test board. Meanwhile, the method's robust anti-noise capability is confirmed through simulation experiments. Through the conversion of the complexity of optical design to a post-processing algorithm, this method offers an economical and efficient strategy for obtaining high-resolution and high-quality images using a simple large-field lens.
暂无评论