The optical quality for some special human eyes was evaluated from wavefront aberration data. Wavefront aberrations
were measured by a ray-tracing wavefront aberrometer. The optical quality was estimated by means of objective and
quantitative optical quality metrics of human eyes. The results show that the point spread function patterns and the
values of six optical quality metrics vary with the individual eyes or the levels of aberration. The values of PFWc, SRX,
AreaMTF and SRMTF increase, as well as the values of RMSs and SM decrease, with the more corrected aberration
orders. The great increase of higher-order aberration may be attributed to the pathological changes or refractive surgery,
which results in the distinct degeneration of optical quality of human eye.
KEYWORDS: Image processing, Digital holography, Digital image processing, Holography, Image filtering, Binary data, Data storage, 3D image reconstruction, Holographic data storage systems, Image quality
Firstly, this paper introduces the concept of multi-level digital holographic storage. Then, application of digital image processing technology is brought forward in the data restoring process of digital holographic storage. Information in the reconstructed digital images collected from CCD camera is enhanced through digital image processing technology and threshold decision is gone on so as to decreasing bit error ratio of system. Based on above-mentioned ideal, the programming project is designed, which is applicable to binary and multi-level digital holographic storage. Finally, the quality of a binary experimental image is improved through digital image processing program and the accuracy of threshold decision can be improved.
The fracture toughness of high-temperature alloy material under high-temperature is tested with the laser moire interfrometric device. The zero-thickness grating is etched on the surface of test piece by electrochemical method directly, expanding the research space of high-temperature alloy’s moire interferometry. The moire fringe is collected and analyzed by CCD imaging system of computer, the test result that indicates imaging quality and measurement precision of moire interferometry are improved.
This paper analyzes the reflection index modulation distribution and the corresponding spectrum characteristic of the holographic reflection gratings fabricated by Lippman light path under the condition of recording medium absorption being taken into account. The emphasis of discussion is placed on the relationship of secondary peak characteristic of the holographic reflection gratings, bandwidth and the distribution of refraction index modulation under this recording condition, calculating and simulating the distribution curve of refraction index modulation and the corresponding spectrum characteristic curve of diffraction gratings, and the comparison with the holograph gratings recorded by symmetrical light path. The result of calculation shows that there is obvious difference between the spectrum characteristic curve of Lippman holographic gating and that of symmetrical light path, and the secondary peak value of Lippman holographic gratings is lower than that of symmetric light path under the condition of the same reflection index modulation, while the medium of recording is thicker (thicker than 60μm) or the non-linear modulation of refraction index is relatively large, and the higher secondary peak of Lippman holographic gratings presents saw-like and non-degressive, whereas this phenomenon has never occurred in the holographic gratings diffraction recorded by the symmetrical path. This result obtained by calculation and simulation is consistent with experimental result.
KEYWORDS: Digital holography, Holography, Data storage, 3D image reconstruction, Holographic data storage systems, Binary data, Image processing, Image storage, Digital image processing, Remote sensing
This paper brings forward one concept of holographic storage of multi-level digital data at first. It is that each pixel includes more information than 1 bit, which means that a multi-level digital data image provides more information than a binary digital data image with the same pixels. So, the capacity will be increased with this technology. Furthermore, some aspects of holographic storage of multi-level digital data, such as the multi-level coding, storage characters and the quality of the stored image are debated. Finally, we research this holographic storage technology by experiment.
In this paper, the diffractive efficiency in Ce:SBN photorefractive crystal was measured using two-wave coupling light path. The light-induced scattering resistance was gained through observing the transmitted light spot. Furthermore the other holographic storage properties such as the quality of the stored image and preservation time were studied. Finally using Ce:SBN photorefractive crystal as the storage medium, storing and reconstructing the holographic image were realized.
A new technique with a one-step rainbow hologram for recording 2-dimension or 3-dimension images is presented. In this method, not only can we realize to record rainbow hologram in the same recording material with multiplex angles, but also obtain laminated result. The hologram has a low speckle noise and a high diffraction efficiency when it reconstructed with white light.
This paper presents a new way for making circular hologram gratings with high-density and equidistance, namely to use reflection interference formed by cone mirror to obtain circular interference with equal fringe spacing. The intensity distribution of interference field of reflection formed by cone mirror and the method for recording hologram gratings are given. The author suggests that this way for fabricating circular hologram gratings will find extensive use in optical testing and fiber-optic devices (such as DWDM and DBR).
KEYWORDS: Holograms, Signal to noise ratio, Refractive index, Water, Modulators, Image quality, Temperature metrology, Californium, Holography, Signal processing
The experiment has indicated in this paper that dichromated gelatin (DCG) holograms after the first development can be reprocessed. The quality of over exposed of multi-exposed DCG holograms can be improved by reprocessing. This is especially beneficial for the DCG hologram with short developed time in the first development processing.
The digital fiber optic sensing system used for real-time remote measurement of the amount of oil in a tanker is described. The system consists of a fiber optic (FO) interface-temperature complex probe, a driving mechanism for the FO probe, and a microcomputer-based integrated data processing unit. It has been proven by the analogue experiment of the system that the gauging of the amount of oil is accurate within +/- 0.2%.
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