View Full Term. By clicking sign up, you agree to receive emails from Techopedia and agree to our Terms of Use and Privacy Policy. An optical scanner is an input device using light beams to scan and digitally convert images, codes, text or objects as two-dimensional 2D digital files and sends them to computers and fax machines. Flatbed scanning devices are the most popular optical scanners. Optical scanners are used for many purposes, including reading customized response forms, creating automated data fields and recording fingerprints.
Willard Boyle and George Smith developed the optical scanner technology in An optical scanner is based on a charge-coupled device CCD composed of light-sensitive receptors.
CCD capacitors respond to up to 70 percent of incident light versus photographic film which respondg to only 2 percent. The scanning device moves back and forth on the track to scan whatever is placed above it. Optical scanners are also used to record fingerprints and votes from ballots, scan entire books or libraries, and serve as "eyes" for the blind that convert text into automated speech.
Because different exposure conditions can cause radically different images to appear, optical scanners are equipped with proprietary software that corrects for these conditions to produce a consistent image.
Wireless adapters for optical scanners also exist. In our implementation a narrow focus line is scanned over the sample and the reflected light is measured in a confocal arrangement. One such scan is equivalent to a transverse projection in tomography.
Repeating the scanning procedure in several directions, a number of transverse projections are recorded from which the image can be obtained using conventional CT reconstruction algorithms. The resolution of the image is independent of the spatial dimensions and structure of the applied detector; furthermore, the transfer function of the system is isotropic. The imaging performance of the implemented confocal LSTOM was compared with a point- scanning confocal microscope, based on recorded images.
Biological applications of near-field scanning optical microscopy. Near-field Scanning Optical Microscopy NSOM is a true optical microscopic technique allowing fluorescence, absorption, reflection and polarization contrast with the additional advantage of nanometer lateral resolution, unlimited by diffraction and operation at ambient conditions. NSOM based on. Optical modeling and simulation of thin-film photovoltaic devices. In wafer-based and thin-film photovoltaic PV devices , the management of light is a crucial aspect of optimization since trapping sunlight in active parts of PV devices is essential for efficient energy conversions.
Optical modeling and simulation enable efficient analysis and optimization of the optical situation in optoelectronic and PV devices.
Optical Modeling and Simulation of Thin-Film Photovoltaic Devices provides readers with a thorough guide to performing optical modeling and simulations of thin-film solar cells and PV modules. It offers insight on examples of existing optical models. Near-field scanning optical microscopy using polymethylmethacrylate optical fiber probes. The sharp tips were prepared by chemical etching of the fibers in ethyl acetate, and the probes were prepared by proper gluing of sharpened fibers onto the tuning fork in the conditions of the double resonance working frequency of a tuning fork coincides with the resonance frequency of dithering of the free-standing part of the fiber reported earlier for the case of glass fibers.
Quality factors of the probes in the range were obtained, which enables the realization of an excellent topographical resolution including state-of-art imaging of single DNA molecules.
Near-field optical performance of the microscope is illustrated by the Photon Scanning Tunneling Microscope images of fluorescent beads with a diameter of nm. Comparative study of the retinal nerve fibre layer thickness performed with optical coherence tomography and GDx scanning laser polarimetry in patients with primary open-angle glaucoma.
We compared the parameters of retinal nerve fibre layer in patients with advanced glaucoma with the use of different OCT Optical Coherence Tomograph devices in relation to analogical measurements performed with GDx VCC Nerve Fiber Analyzer with Variable Corneal Compensation scanning laser polarimetry.
Study subjects had advanced primary open-angle glaucoma, previously treated conservatively, diagnosed and confirmed by additional examinations visual field, ophthalmoscopy of optic nerve, gonioscopy , A total of 10 patients were enrolled 9 women and 1 man , aged years of age.
Nineteen eyes with advanced glaucomatous neuropathy were examined. The parameters of the retinal nerve fibre layer thickness are highly correlated between the GDx and OCT Stratus and 3D OCT devices in mean retinal nerve fibre layer thickness, retinal nerve fibre layer thickness in the upper sector, and correlation of NFI GDx with mean retinal nerve fibre layer thickness in OCT examinations.
Examination with OCT devices is a sensitive diagnostic method of glaucoma, with good correlation with the results of GDx scanning laser polarimetry of the patients. Development of scanning micromirror with discrete steering angles.
This paper describes the development of a new MEMS-based optical mirror, which can perform optical switching or scanning function with discrete reflection angles in an outof- plane configuration. The most outstanding feature of this MEMS mirror is the discrete and therefore, reliable tilting angles, which generated by its unique mechanical structural design and electrostatic-driven mechanism.
In this paper, the concept of the new scanning mirror is presented, followed by the introduction of device design, mechanical simulation, microfabrication process, assembly solution, and some testing results.
The potential applications of this new MEMS mirror include optical scanning , optical sensing or detection , and optical switching. Optical microscope illumination analysis using through-focus scanning optical microscopy. Misalignment of the aperture diaphragm present in optical microscopes results in angular illumination asymmetry ANILAS at the sample plane. This could lead to substantial errors in quantitative results for optical methods that use through-focus images such as three-dimensional nanoparticle tracking, confocal microscopy, and through-focus scanning optical microscopy TSOM.
Design issues for semi-passive optical communication devices. Optical smart cards are devices containing a retro-reflector, light modulator, and some computing and data storage capabilities to affect semi-passive communication. They do not produce light; instead they modulate and send back light received from a stationary unit. These devices can replace contact-based smart cards as well as RF based ones for applications ranging from identification to transmitting and validating data.
Since their transmission is essentially focused on the receiving unit, they are harder to eavesdrop than RF devices , yet need no physical contact or alignment. In this paper we explore optical design issues of these devices and estimate their optical behavior. Specifically, we analyze how these compact devices can be optimized for selected application profiles.
Some of the key parameters addressed are effective light efficiency how much modulated signal can be received by the stationary unit given the amount of light it transmits , range of tilt angles angle between device surface normal to the line connecting the optical smart card with the stationary unit through which the device would be effective, and power requirements of the semi-passive unit.
In addition, issues concerning compact packaging of this device are discussed. Finally, results of the analysis are employed to produce a comparison of achievable capabilities of these optical smart cards, as opposed to alternative devices , and discuss potential applications were they can be best utilized. Meso- optical Fourier transform microscope - a new device for high energy physics.
Astakhov, A. A new device for high energy physics, the Meso- optical Fourier Transform Microscope MFTM , designed for observation fo straight line particle tracks in nuclear research emulsion is described.
The MFTM works without any mechanical or electronical depth scanning and can be considered as a selectivity viewing 'eye'. The computer controlled system containing MFTM as its main unit is given.
This system can be used for a fast search for particle tracks and events produced by high energy neutrinos from particle accelerators. The results of the first experimental test of the computer controlled MFTM are presented. The performance of this system is described and discussed. It is shown that the angular resolution of the MFTM is 1 angular minute and the measurement time is equal to 30 ms per image.
As all operations in the MFTM proceed without any depth scanning , this new evaluation system works at least two orders of magnitude faster than any known system with a traditional optical microscope. Magneto- optical non-reciprocal devices in silicon photonics. Full Text Available Silicon waveguide optical non-reciprocal devices based on the magneto- optical effect are reviewed.
The non-reciprocal phase shift caused by the first-order magneto- optical effect is effective in realizing optical non-reciprocal devices in silicon waveguide platforms. In a silicon-on-insulator waveguide, the low refractive index of the buried oxide layer enhances the magneto- optical phase shift, which reduces the device footprints. A surface activated direct bonding technique was developed to integrate a magneto- optical garnet crystal on the silicon waveguides.
A silicon waveguide optical isolator based on the magneto- optical phase shift was demonstrated with an optical isolation of 30 dB and insertion loss of 13 dB at a wavelength of nm. Furthermore, a four port optical circulator was demonstrated with maximum isolations of Adaptive optics scanning laser ophthalmoscopy in combination with en-face optical coherence tomography.
The human retina is a most important tissue and plays a fundamental role for the vision. Diseases of the eye affect the normal retinal function which, if untreated, may lead to vision loss or ultimately to blindness.
Thus, in vivo diagnostic tools that provide detailed information on the retinal status are required in order to improve diagnosis and treatment. In recent years, several new optical imaging methods of the human retina have been developed and now represent the key part in a standard ophthalmic examination process.
One of these technologies is optical coherence tomography OCT , which provides images of the retina noninvasively and with a high axial resolution. However, imperfections of the eye's optics cause aberrations of the wavefront of the imaging light, thus limiting the transverse resolution of such systems.
Improvements in the resolution of retinal images are necessary to resolve individual cells e. Adaptive optics AO , a technology known from astronomy, may be used to increase image resolution. Aberrations of the imaging light are measured and corrected, resulting in an increase of lateral resolution up to the diffraction limit. Within this thesis, AO was combined with a scanning laser ophthalmoscope SLO that enables high resolution imaging of the retina.
Measurements on healthy subjects demonstrated the ability of the system to resolve foveal cones the smallest cone photoreceptors within the retina and even rod photoreceptors. However, the depth resolution of the system remained limited compared to OCT instruments.
The OCT system is based on transversal scanning TS -OCT which records en-face images of the retina and incorporates a high-speed axial eye tracking device. Evaluation of acute radiation optic neuropathy by B- scan ultrasonography. We studied the accuracy of B- scan ultrasonography to diagnose radiation-induced optic neuropathy in 15 patients with uveal melanoma. Optic neuropathy was diagnosed by an observer masked as to clinical and photographic data.
We analyzed planimetry area measurements of the retrobulbar nerve before and after irradiation. The retrobulbar area of the optic nerve shadow on B- scan was quantitated with a sonic digitizer. Increased optic nerve shadow area was confirmed in 13 of 15 patients who had radiation optic neuropathy P less than. The correct diagnosis was confirmed when the results of ultrasound were compared to fundus photography and fluorescein angiography.
In 13 patients there was acute radiation optic neuropathy. Two patients did not show an enlarged retrobulbar optic nerve, and the clinical appearance suggested early progression to optic atrophy. Ultrasonography documents the enlargement of the optic nerve caused by acute radiation changes. Optical fiber end-facet polymer suspended-mirror devices. This paper presents a novel optical fiber device based on a polymer suspended mirror on the end facet of an optical fiber.
With an own-developed optical 3D micro-printing technology, SU-8 suspended-mirror devices SMDs were successfully fabricated on the top of a standard single-mode optical fiber. Optical reflection spectra of the fabricated SU- 8 SMDs were measured and compared with theoretical analysis. The proposed technology paves a way towards 3D microengineering of the small end-facet of optical fibers to develop novel fiber- optic sensors.
Reflective afocal broadband adaptive optics scanning ophthalmoscope. A broadband adaptive optics scanning ophthalmoscope BAOSO consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented.
The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square RMS of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter D vergence range. This vergence range allows for the use of any broadband light source s in the nm wavelength range to simultaneously image any combination of retinal layers.
Imaging modalities that could benefit from such a large vergence range are optical coherence tomography OCT , multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with and nm peak wavelengths, reaching the eye with a vergence of 0.
Optical depth sectioning in the aberration-corrected scanning transmission and scanning confocal electron microscope. The use of spherical aberration correctors in the scanning transmission electron microscope STEM has the effect of reducing the depth of field of the microscope, making three-dimensional imaging of a specimen possible by optical sectioning.
Depth resolution can be improved further by placing aberration correctors and lenses pre and post specimen to achieve an imaging mode known as scanning confocal electron microscopy SCEM.
The OTF for a STEM is shown to have a missing cone region which results in severe blurring along the optic axis, which can be especially severe for extended objects. We also present strategies for reconstruction of experimental data, such as three-dimensional deconvolution of the point spread function.
Fan-beam scanning laser optical computed tomography for large volume dosimetry. A prototype scanning -laser fan beam optical CT scanner is reported which is capable of high resolution, large volume dosimetry with reasonable scan time.
An acylindrical, asymmetric aquarium design is presented which serves to 1 generate parallel-beam scan geometry, 2 focus light towards a small acceptance angle detector, and 3 avoid interference fringe-related artifacts. Preliminary experiments with uniform solution phantoms 11 and 15 cm diameter and finger phantoms Nanometrology using a through-focus scanning optical microscopy method.
We present an initial review of a novel through-focus scanning optical microscopy TSOM pronounced as 'tee-som' imaging method that produces nanometer-dimensional measurement sensitivity using a conventional bright-field optical microscope. In the TSOM method a target is scanned through the focus of an optical microscope, acquiring conventional optical images at different focal positions.
The TSOM images are constructed using the through-focus optical images. A TSOM image is unique under given experimental conditions and is sensitive to changes in the dimensions of a target in a distinct way. We use this characteristic for nanoscale-dimensional metrology. This technique can be used to identify the dimension which is changing between two nanosized targets and to determine the dimensions using a library-matching method. This methodology has potential utility for a wide range of target geometries and application areas, including nanometrology, nanomanufacturing, defect analysis, inspection, process control and biotechnology.
Full Text Available Purpose. All procedures were performed by the same operator. The mean values obtained by the Visante OCT were Transmission environmental scanning electron microscope with scintillation gaseous detection device.
A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented.
This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration.
This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole.
Lab-on-fiber electrophoretic trace mixture separating and detecting an optofluidic device based on a microstructured optical fiber. We report an in-fiber integrated electrophoretic trace mixture separating and detecting an optofluidic optical fiber sensor based on a specially designed optical fiber. In this design, rapid in situ separation and simultaneous detection of mixed analytes can be realized under electro-osmotic flow in the microstructured optical fiber.
To visually display the in-fiber separating and detecting process, two common fluorescent indicators are adopted as the optofluidic analytes in the optical fiber. Results show that a trace amount of the mixture 0. Simultaneously, the distributed information of the separated analytes in the optical fiber can be clearly obtained by scanning along the optical fiber using a nm laser.
The emission from the analytes can be efficiently coupled into the inner core and guides to the remote end of the optical fiber. In addition, the thin cladding around the inner core in the optical fiber can prevent the fluorescent cross talk between the analytes in this design. Compared to previous optical fiber optofluidic devices , this device first realizes simultaneously separating treatment and the detection of the mixed samples in an optical fiber.
Significantly, such an in-fiber integrated separating and detecting optofluidic device can find wide applications in various analysis fields involves mixed samples, such as biology, chemistry, and environment.
An optical scanning subsystem for a UAS-enabled hyperspectral radiometer. National Aeronautics and Space Administration — Hyperspectral radiometers will be integrated with an optical scanning subsystem to measure remote sensing reflectance spectra over the ocean.
The entire scanning All optical regeneration using semiconductor devices. All- optical regeneration is a key functionality for implementing all- optical networks.
We present a simple theory for the bit-error-rate in links employing all- optical regenerators, which elucidates the interplay between the noise and and nonlinearity of the regenerator. A novel device structure Full Text Available The dimension of biomolecules is of few nanometers, so the biomolecular devices ought to be of that range so a better understanding about the performance of the electronic biomolecular devices can be obtained at nanoscale.
Development of optical biomolecular device is a new move towards revolution of nano-bioelectronics. Optical biosensor is one of such nano-biomolecular devices that has a potential to pave a new dimension of research and device fabrication in the field of optical and biomedical fields.
This paper is a very small report about optical biosensor and its development and importance in various fields. To demonstrate the viability of improving transverse image resolution in reflectance scanning adaptive optics ophthalmoscopy using sub-Airy disk confocal detection. The foveal cone mosaic was imaged in five human subjects free of known eye disease using two custom adaptive optics scanning light ophthalmoscopes AOSLOs in reflectance with 7.
Confocal pinholes of 0. Average cone photoreceptor intensity profile width and power spectrum were calculated for the resulting images.
Detected energy using a model eye was recorded for each pinhole size. The cone photoreceptor mosaic is better resolved with decreasing confocal pinhole size, with the high spatial frequency content of the images enhanced in both the large- and small-pupil AOSLOs. The use of sub-Airy disk confocal pinhole detection without increasing retinal light exposure results in a substantial improvement in image resolution at the cost of larger than predicted signal reduction.
Improvement in transverse resolution using sub-Airy disk confocal detection is a practical and low-cost approach that is applicable to all point- and line- scanning ophthalmoscopes, including optical coherence tomographers. Nanophotonic Devices for Optical Interconnect. We review recent progress in nanophotonic devices for compact optical interconnect networks. We focus on microdisk-laser-based transmitters and discuss improved design and advanced functionality including all- optical wavelength conversion and flip-flops.
Next we discuss the fabrication uniformity Finally, we discuss the performance of a wavelength selective detector All the images were processed with the signal normalization.
A set of images formed a questionnaire with 24 pairs of cross-sectional images from each eye with any combination of the three SD-OCT devices either both pre- or postsignal normalization. Observers were asked to evaluate the similarity of the two displayed images based on the image appearance. The effects on reducing the differences in image appearance before and after processing were analyzed.
Twenty-nine researchers familiar with OCT images participated in the survey. The signal normalization successfully minimized the disparities in the image appearance among multiple SD-OCT devices , allowing clinical interpretation and comparison of OCT images regardless of the device differences. The signal normalization would enable direct OCT images comparisons without concerning about device differences and broaden OCT usage by enabling long-term follow-ups and data sharing.
In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners.
This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique.
It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. Calibration evaluation results are presented and examples of first underwater measurements are given. Inspection of commercial optical devices for data storage using a three Gaussian beam microscope interferometer. Recently, an interferometric profilometer based on the heterodyning of three Gaussian beams has been reported. We report the use of this interferometer to measure the profiles of two commercially available optical surfaces for data storage, namely, the compact disk CD-R and the digital versatile disk DVD-R.
We include experimental results from a one-dimensional radial scan of these devices without data marks. The measurements are taken by placing the devices with the polycarbonate surface facing the probe beam of the interferometer. This microscope interferometer is unique when compared with other optical measuring instruments because it uses narrowband detection, filters out undesirable noisy signals, and because the amplitude of the output voltage signal is basically proportional to the local vertical height of the surface under test, thus detecting with high sensitivity.
We show that the resulting profiles, measured with this interferometer across the polycarbonate layer, provide valuable information about the track profiles, making this interferometer a suitable tool for quality control of surface storage devices. Scanning laser ophthalmoscope design with adaptive optics. A design for a high-resolution scanning instrument is presented for in vivo imaging of the human eye at the cellular scale. In this system, the ocular wavefront aberrations that reduce the resolution of conventional SLOs are detected by a Hartmann-Shack wavefront sensor, and compensated with two deformable mirrors in a closed-loop for dynamic cor Compact integrated optical devices for optical sensor and switching applications.
This thesis describes the design, fabrication, and characterization of compact optical devices for sensing and switching applications. Our focus has been to realize the devices using CMOS-compatible fabrication processes. Particularly the silicon photonics fabrication platform, ePIXfab, has been. Integrated Optical lightguide device. In an integrated optical lightguide device including a light-transmitting core layer, an inclusion or buffer layer, and an active or cladding layer.
The 3-D beamforming information such as tilt and lensing refractive index gradients are stored in large area birefringent phase plates.
These phase plates can be electronically programmable thin film devices like birefringent-mode BM multi-pixel NLC devices or fixed phase pattern phase plates made from a variety of materials such as the PTR glasses. Depending on the spatial frequency content of the synthesized birefringent phase plates, both wide angle and small angle beam control can be simultaneously provided by the P-MOS.
The key asset of the P-MOS is maximum hardware compression, as 20 stages can provide over a million independent beams in space. The T-MOS features complete beam programmability and adaptability using mature and reliable components.
This application proposes two new types of scanners using multiplexing of wavelengths and spatial codes. In effect, independent exploitation of optical code switching via a high speed SLM is used to access 3-D phase perturbations stored in optical storage materials such as large area fixed phase sensitive photothermal refractive PTR glasses, photorefractive crystals, or any other holographic storage devices to realize a high speed C-MOS.
In the W-MOS, high speed wavelength selection or tuning is used in conjunction with wavelength dispersive elements to realize scanning optical beams. It has been known see J. Rosen, M. Segev and A. This is an example of multi-wavelength information retrieval where no high speed scanning or tuning of wavelengths is proposed.
Use of multiple simultaneous wavelengths with a single fiber and a wavelength dispersive element to form a multi-point sensor head was proposed in N.
Digest, pp. Later, a similar multi-wavelength starring concept see G. Tearney, R. Webb, and B. Again, no fast tuning of the wavelength is exploited. Use of simultaneous multiple wavelengths was also used for transmitting an image through a single fiber see D. Mendlovic, J. Garcia, Z. Zalevsky, E.
Marom, D. Mas, C. Ferreira, and A. Similarly, multiwavelengths were also proposed for reading two-dimensional orthogonal codes used in a spatial code division multiple access optical communication fiber network see N.
Riza and S. As in G. Xiao, T. Corle, G. Tiziani and H. Again, no high speed tuning of wavelengths is used for scanning. As in M. Krichever, J. Companelli, L. Courtney, P. Fazekas, J. Swartz, V. Gurevich, and B. Here, each beam on a different wavelength has its own moving optics, resulting in its predesigned scan beam. Previously see L. Lembo, T. Holcomb, M. Wickham, P. Wisseman, J. Wavelength selection through programmable optical filters has also been proposed to generate time delays as described in N.
Recently, as proposed in N. Riza and Y. Riza and Z. This scanner has been further described in N. The purpose of this application is first to describe this wavelength tuned or selected scanner and elaborate on its embodiments and innovative application architectures. Note that it is also proposed in N. It is also well known that DOEs can be designed to be highly dispersive.
In this perspective, using the DOE element with the tunable wavelength concept as proposed by N. Riza and combining it with the previously proposed lens chromatic dispersion confocal microscopy application see G.
Li, P. Sun, P. Lin, and Y. C-MOS combines the principles of freespace spatial code division multiple access optical communications see N. Riza, J. Hershey, and A. Salehi and E. On Communications, Vol. The C-MOS operates in a principle that is reverse to that used in previously developed holographic data storage system. Namely, in holographic data storage, information in the form of analog images or digital two dimensional bit maps typically have space bandwidth products of one million points are stored using holography in a storage medium.
Generally, to be cost effective as a memory device, thousands of images are required to be stored in the volume holographic storage element. More over, each individual million point data page must be independently recovered with very low image recovery error rates. Furthermore, image recovery should occur without erasing the other stored data or generating crosstalk between the stored images. These are all very stringent requirements placed by the data storage industry, and as of today, holographic data storage has made great strides, but is yet to meet these requirements.
Various methods have been deployed to record and recover data pages with improved crosstalk levels. These are described in the following prior art on holographic data storage: F. Hong, I. McMichael, T. Chang, W. Christian, E. Burr, F. Mok, and D. Rakuljic, V. Leyva, and A. Bashaw, R. Singer, J. Heanue, and L. Curtis, A. Pu, and D. Heanue, M.
Bashaw, and L. Alves, G. Pauliat, and G. Psaltis, M. Levene, A. Pu, G. Barbastathis, and K. Yang, Y. Xu, Z. Wen, Y. All these holographic storage methods focus on adjusting the reference beams that are used to interfere with the signal beams that carry the image information input from the image or signal SLM. Reference beams have been angularly adjusted, or different wavelength reference beams have been deployed, or two-dimensional phase coding of the reference beams have been deployed to record the many data pages.
In other words, the holographic storage medium must have an information capacity of one billion data points, a very tall requirement for any holographic optical material. The approach to forming the C-MOS is in reverse to the principles and needs of holographic image storage. Namely, in the C-MOS case perhaps a thousand or so beams need to be generated where in the basic C-MOS design case, each beam corresponds to a single point in the far field optical space not a million point image of the scanner.
In other words, a storage system needs to be realized that can recover a thousand single points, not a billion single points. A different way to say this is that in its most basic form i. The implementation of the C-MOS is also reverse to holographic data storage as this time the signal beam is spatially coded with for example different orthogonal spatial codes e.
Walsh and Hadamard orthogonal code sets can be deployed, as used in electronic communications. For example, the reference beam can be generated by a 2-axis mirror with 32 x-tilt positions and 32 y-tilt positions to realize far field points in space x is horizontal and y is vertical directions in the scanner's cartesian coordinate scan space.
Furthermore, more complex 3-D reference beams can be generated using another SLM in the reference beam path. Hence, when a particular 2-D code is input to the signal beam SLM, a particular reference beam is recovered that then acts as the scan beam in the far field for the scanner. This is in exact opposite to the holographic data storage process where a reference beam is generated to recover the data page. Riza introduces the concept of a spatial code division multiple access CDMA scanner, with no moving parts.
A holographic material is used to record scan beam generation holograms using an orthogonal set of spatial codes. When the incident light with right spatial code is incident on the hologram, its corresponding scan beam is generated.
Fast spatial light modulators SLMs can be used to generate and access the spatial codes using optical phase, amplitude and polarization coding formats. The scanner can possess powerful properties such as wide angle scan beams, large number of beams, high resolution scanning, and large aperture scans at high speeds. Prior art has deployed holograms to make scanners, but all with some sort of moving parts thus limiting the scanning speeds.
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