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Optical smoothing is a very effective method to restrict mid-to-high spatial frequency errors generated by computer-controlled sub-aperture polishing technologies. According to Preston’s equation, pressure distribution is the key factor in describing the smoothing effect of a tool. Although the classic bridging model can solve pressure distribution during the smoothing process, it is only suitable for a tool that consists of a rigid base, compliant interlayer, thin metal plate, and pitch polishing layer. In this paper, a mathematical model applicable for any multi-layer polishing tool is proposed, which helps to calculate the pressure distribution dependent on the thickness of the layer, mid-spatial frequency errors at different periods, and the structures of polishing tools. Based on the model, the pressure distributions and smoothing rates of a rigid tool and a semi-flexible tool are deduced and compared in detail. Validity and improvement in accuracy are verified by comparison with the finite element model. In addition, three groups of experiments using a rigid tool and a semi-flexible tool for smoothing 4 mm and 8 mm period errors generated by magnetorheological finishing are carried out to validate the model. The simulation result of the smoothing rates of the errors after every smoothing process matches well with the experiment results.

Large-aperture aspheric mirror is usually transferred to the test axis by rotating and translating when measured by a computer-generated hologram(CGH). This paper focused on the optimal design of CGH, minimizing the line density of CGH, in testing off-axis aspheric mirror with large aperture, off-axis amount and asphericity. The analytics formula of the transferred aspheric is used for deriving the phase function of CGH by geometric computing. And the precision of optical path difference(OPD) is proved reaching nanometer level for aspheric mirror with large asphericity by zemax. The defocus and tilt-carrier amount are two parameters to be optimized for filtering the unwanted orders brought out by CGHs. A merit function consists of the line densities at lower and upper boundaries of CGH to describe the etching difficulty of CGH is proposed. The propagation progress is analyzed while the reflection is amended by considering the saggital height of the reflection point. The separated distance of the given (m,n) orders ray is proved reaching micron degree. The filtering condition is expressed as an inequalities system. The gradient descent method with Karush Kuhn Tucker condition is used for optimal solution of the constrained optimization problem. Finally, design example is presented and the parameter optimization for testing off-axis aspheric mirrors is proved to have a high precision, which providing extensive applicability possibility in designing freeform testing system.

Indirect X-ray imaging detectors consisting of scintillator screens, long-working-distance microscope lenses and scientific high-speed complementary metal-oxide semiconductor (CMOS) cameras are usually used to realize fast X-ray imaging with white-beam synchrotron radiation. However, the detector efficiency is limited by the coupling efficiency of the long-working-distance microscope lenses, which is only about 5%. A long-working-distance microscope lenses system with a large numerical aperture (NA) is designed to increase the coupling efficiency. It offers an NA of 0.5 at 8× magnification. The Mitutoyo long-working-distance microscope lenses system offers an NA of 0.21 at 7.5× magnification. Compared with the Mitutoyo system, the developed long-working-distance microscope lenses system offers about twice the NA and four times the coupling efficiency. In the indirect X-ray imaging detector, a 50 µm-thick LuAG:Ce scintillator matching with the NA, and a high-speed visible-light CMOS FastCAM SAZ Photron camera are used. Test results show that the detector realized fast X-ray imaging with a frame rate of 100000 frames s−1 and fast X-ray microtomography with a temporal sampling rate up to 25 Hz (25 tomograms s−1).

Field enhancement effect of metal probe in evanescent field, induced by using a multi-layers structure for exciting surface plasmon resonance (SPR), is analyzed numerically by utilizing two-dimensional (2D) TM-wave finite difference time-domain (FDTD) method. In this letter, we used a fundamental mode Gaussian beam to induce evanescent field, and calculated the electric intensity. The results show that compared with the nonmetal probe, the metal probe has a larger field enhancement effect, and its scattering wave induced by field enhancement has a bigger decay coefficient. The field enhancement effect should conclude that the metal probe has an important application in nanolithography.

The focusing properties of a concentric piecewise cylindrical vector beam is investigated theoretically in this paper. The beam consists of three portions with different and changeable phase retardation and polarization. Numerical simulations show that the evolution of the focal shape is very considerable by changing the radius and polarization rotation angle of each portion of the vector beam. And some interesting focal spots may occur, such as two- or three-peak focus, dark hollow focus, ring focus, and two-ring-peak focus. Corresponding gradient force patterns are also computed, and novel trap patterns, including cup shell shape trap with one trap at its each side along axis, rectangle shell shape trap with one trap at its each side, dumbbell optical trap, spherical shell optical trap, may occur, which shows that the concentric piecewise cylindrical vector beam can be used to construct controllable optical tweezers.

Blue ray optical storage is one of the important trends in the area of information storage, and attracts a number of researchers. Static tester for blue ray optical storage plays an important role in storage media research. We designed and constructed a static tester, in which modularization makes it very convenient to expand function. Employment of modulation/demodulation technique weakens test error so as to increase test precision. Focus move mode and the nano-positioners facilitate the relocation of recording marks. Only one laser with wavelength 406.7 nm is used. In this paper, system design and characteristics are represented in detail, and some experimental results are also given to show that the static tester can perform successfully, acting as research platform for blue ray optical storage.

We quantitatively analysed the factors contributing to the optical transmission enhancement of a sub-wavelength Sb thin film lens, using the finite-difference time-domain (FDTD) method. The results show that the transmission enhancement of the dielectric with a Gaussian distributed refractive index loaded in a sub-wavelength circular hole is not only due to the high refractive index dielectric, but also due to the specific distributions of refractive index. It is the first study about the effects of the refractive index distribution on the transmission of a sub-wavelength aperture. This kind of lens has practical applications in the very small aperture lasers and for near-field optical storage and lithography.

Static recording characteristic of super-resolution near-field structure with antimony (Sb) is investigated in this paper. The recording marks are observed by a scanning electron microscopy (SEM), a high-resolution optical microscopy with a CCD camera and an atomic force microscopy (AFM). The super-resolution mechanism is also analyzed based on these static recording marks. Results show that the light reaching on recording layer is composed of two parts, one is the linear transmissive light (propagating field) and the other is the nonlinear evanescent light in the optical near field. The evanescent light may be greatly enhanced in the center of the spot because Sb will transit from a semiconductor to a metal when it is melted under the high laser power irradiation. This local melted area in the spot center may be like a metal tip in the optical near field that can collect and enhance the information that is far beyond the diffraction limit, which leads to the super-resolution recording and readout.

The effective refractive index of a kind of granular composite, which consists of granular metallic and magnetic inclusions with different radius embedded in a host medium, is theoretically investigated. Results show that for certain volume fractions of these two inclusions, the negative permittivity peak shifts to low frequency and the peak value increases with increasing radius ratio of the radius of magnetic granulae to that of metallic granulae. Simultaneously, peak value of permeability decreases with the radius ratio, and value peak shifts to high frequency with increasing volume fraction of magnetic inclusion. Therefore, the radius ratio can affect the effective refractive index considerably, and it is found that by adjusting the radius ratio, the refractive index may change between negative and positive values for certain volume fractions of the two inclusions.

In this paper, the evolution of the gradient force pattern, focal shift, and focal switch induced by a three-portion pure phase-shifting apodizer is numerically investigated in detail. The results show that the proposed apodizer may induce tunable gradient force on the particles in the focal region, focal shift, and focal switch. By adjusting the geometrical parameters of the phase-shifting apodizer, multiple traps may occur with changeable distance between them, and the shape of the optical trap also evolves evidently. More interestingly, for certain geometrical parameters of the proposed apodizer, by changing the phase shift of inner annular portion, the considerable focal shift may occur with focal switch accompanying, which is discussed to show that this kind of apodizer may be a very promising method of transporting trapped particles.

Super-resolution near-field structure (super-RENS) with bismuth (Bi) mask layer (Bi-super-RENS) is reported for the first time in this paper. Bi thin films with various thicknesses were studied by atomic force microscopy and grazing incident X-ray diffraction. Static optical recording tests with and without super-RENS were carried out using 650 nm semiconductor laser at recording power of 14 mW and 7 mW with pulse duration of 100 ns. The recording marks were observed by scanning electron microscopy and high-resolution optical microscopy with a CCD camera. Results showed that the Bi mask layer can also concentrate energy into the center of a laser beam at low laser power similar to the traditional Sb mask layer. Moreover, a (ZnS)80(SiO2)20 protection layer performed better than the SiN protection layer in the Bi-super-RENS. The direct observation of laser-recording marks may help better understand the working mechanism of the super-RENS, super-resolution ablation, and other nonlinear switch phenomena.

Effect of a pure phase-shifting apodizer on the three-dimensional light intensity distribution in focal region is theoretically investigated in this paper. The results show that the proposed apodizer may induce focus splitting and local minimization of light intensity. By adjusting the geometrical parameters of the phase-shifting apodizer, the focus can split into two or three peaks. And one or two local minimums of light intensity may occur between two intensity peaks. Under the condition of two-peak focus, the distance between the peaks is tunable by the apodizer.

According to the change of refractive index of Sb thin film with temperature and the radial distribution of temperature within the spot, we consider the dynamic optical aperture as a self-focusing thermal lens of Sb thin film in super-resolution near-field structure of SiN/Sb/SiN, and obtain the radius of the dynamic optical aperture (self-focusing thermal lens) 80 nm, the focusing length 22.5 nm, and the diameter of spot through the self-focusing thermal lens 100 nm by setting the Sb thin film thickness 30 nm, laser power 2 mW, and irradiation time on the Sb thin film 1.45 ns. At the same time, the intensity of spot focused by the self-focusing thermal lens of Sb thin films can be greatly enhanced. The working mechanism of Sb thin film in super-resolution near-field structure of SiN/Sb/SiN has been explained.

Adopting mask during proton implantation, we obtain several areas with different proton implantation in a single wafer of GaAs/AlGaAs asymmetrically coupled double quantum wells (ACDQW) grown by MBE, and investigated the characteristics using photoluminescence (PL) and photo-modulated reflectance (PR) spectroscopy. Without rapid thermal annealing, the maximum transition energy shift of 82 meV in a single wafer has been obtained in different areas. The diffusion length of Al is deduced according to spectrum, and compared with that calculated by diffusion coefficient function. It might be very useful for both edge-emitting laser or VCSELs in GaAs-based materials to provide index guiding and better optical design for devices. It is also a good method to set up a library for optimizing the ion implantation processes.

The local field enhancement generates in the vicinity of the tip which has approached to surface plasmon resonance (SPR) region of the sample. The power of the local field enhancement could be utilized to pattern the sample, and this new lithography method is called probe inducing surface plasmon resonance nanolithography (PSPRN). Owing to the high energy density of local field enhancement and super-diffraction limiting character, PSPRN has the advantages of low power consumption and high resolution. The influence of various film parameters on SPR was simulated by eigenmatrix method in this paper. Through analysis and by comparison, glass ZF6, silver (Ag), silicon dioxide (SiO 2 ) and silver oxide (AgO x ) were selected as the materials for prism, metal layers, protecting layers and recoding layers respectively. A PSPRN experiment was implemented on an atomic force microscope (AFM). In the experiment, samples with single-layer, double-layer, and three-layer structures were researched. Holes of 100nm / 18nm, 75nm / 7nm and 195nm / 7.5nm (diameter/depth) were written into the three structures respectively. However, the result was not ideal with three-layer structure. The influence of diverse parameters on the size of lithography point has been analyzed, which could help providing the theory basis for improving experiment equipment.

A new system of observing and measuring magnetic domain is designed in this paper. The system includes three parts - the principal part of observing and measuring the magnetic domain, the crate controller and the computer used to control the whole system. The principal part consists of x-y scanner, z scanner, digital source meter, ion blower, optical microscope, and giant magnetic resistor (GMR) magnetic head. The GMR magnetic head in this system can be intact after a long-time running in the ordinary laboratory by taking some measures of eliminating electrostatic discharge (ESD). We successfully observed the magnetic domain written in a nanomagnetic material and measured the size of the magnetic domain by use of the new system. The system is very simple and inexpensive, and it has high resolution and signal-to-noise.

We report a method for testing small light spot produced by an optical system with high numerical-aperture (NA). A high NA objective was used to converge the incident linear polarized light, and a tapered optical fiber probe with an opening of 50-80 nm mounted in the near-field optical microscopy (SNOM) apparatus was used to measure light intensity. The small light spot can be measured with high spatial resolution. The results show that a resolution of 50~100 nm can be obtained.

Static recording characteristics of super-resolution near-field structure with bismuth (Bi) mask layer and antimony (Sb) mask layer were investigated and compared. The experimental results show that Bi mask layer can also concentrate energy into the center of a laser beam at a low laser energy input similar to Sb, which may be because that Bi film exhibits giant nonlinearity at low laser intensity. The direct observation of laser-recording marks may help better understand the working mechanism of the super-RENS, super-resolution ablation, and other nonlinear switching phenomena.

In this paper, we use diffractive superresolution technology to design a pure-phase plate for realizing the smaller spot size than the usual Airy spot size. We have calculated 2,3,4,5 circulation zones for optimizing the highest energy compression (Strelratio) with the constraint of the Firstzero value G=0.8. Numerical results show that the 2-circular zone pure-phase plate can yield the highest Strelratio (S=0.59) with the constraint of G=0.8.The 3-circular zone pure-phase plate with the respective phases of φ1φ2φ3 has also been calculated. At the same time the 4,5 circular zone binary phase (0,π) plates are calculated to yield the result of S = 0.57 with G=0.8. The usage of the superresolution phase plate aims to realize the smaller spot size instead of the usage of the higher numerical aperture lens, which is the main advantage of this superresolution technology. Therefore, in this constraint of G=0.8, we have selected the 2-circular zone with binary phase for ease of fabrication. At last, we use a 50 nanometer fiber tip detector to scan the diffractive superresolution light spot in order to compare it with the Airy spot. Detailed experiments are presented.

We have developed a testing system with 514.5 nm argon ion laser to test the static properties of optical disks. The whole testing system is controlled by a computer. The laser power, pulse duration time and external applied magnetic field can be adjusted in a wide range. The focused spot size is less than 1 micrometers on the recording layer which allows high laser power irradiation, up to 30 mW. This testing system can evaluate the writing and erasing characteristics of phase-changes and magneto-optical disks. The design idea and experimental results of this testing system are presented.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The theory and experimental analysis has been made in this paper for the change of phase retardation in optical disk substrates when light beams pass through them from different incident angles. We tested the PC and glass substrate by using a polarization phase modulation method with Polarizer- Modulation-Compensator-Specimen-Analyzer structure.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper proposes a new interferometer to measure the roughness of optical disk substrates, which applies the principle of shearing interferometry and uses a Faraday modulator to detect the phase between two polarized beams. The instrument can produce surface probe and other statistical data with a height sensitivity of 2 nm and a lateral resolution of 1.2 micrometers . It has excellent stability even under vibration conditions, and rapid and noncontact measurements can be made without a special reference surface.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this comment, problems associated with an oversimplified FDTD based model used for trapping force calculation in recent papers "Computation of the optical trapping force using an FDTD based technique" [Opt. Express 13, 3707 (2005)], and "Rigorous time domain simulation of momentum transfer between light and microscopic particles in optical trapping" [Opt. Express 12, 2220 (2004)] are discussed. A more rigorous model using in Poynting vector is also presented.

The three-dimensional distribution of light intensity that is modulated by a pure phase-shifting apodizer is studied. Results show that the Strehl ratio can be altered by the proposed apodizer and by the waist width of incident Gaussian beams. By changing geometrical parameters of the proposed apodizer, we can increase the focal depth to several times that of the original system. The proposed apodizer can also be used to realize focal splitting and local minimum of intensity, which may be advantageous for constructing an optical trap. Furthermore, the local minimum of intensity number is tunable by changing the parameters of the apodizer.

Two novel read-only memory (ROM) disks, one with an AgOx mask layer and the other with an AgInSbTe mask layer, are proposed and studied. The AgOx and the AgInSbTe films sputtered on the premastered substrates with pit depths of 50 nm and pit lengths (space) of 380 nm are studied by atomic force microscopy. Disk readout measurement is carried out using a dynamic setup with a laser wavelength of 632.8 nm and an object lens numerical aperture (NA) of 0.40. Results show that the superresolution effect happens only at a suitable oxygen flow ratio for the AgOx ROM disk. The best superresolution readout effect is achieved at an oxygen flow ratio of 0.5 with the smoothest film surface. Compared with the AgOx ROM disk, the AgInSbTe ROM disk has a much smoother film surface and better superresolution effect. A carrier-to-noise ratio (CNR) of above 40 dB can be obtained at an appropriate readout power and readout velocity. The readout CNR of both the AgOx and AgInSbTe ROM disks have a nonlinear dependence on the readout power. The superresolution readout mechanisms for these ROM disks are analyzed and compared as well. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.