超精密光学镜片三维表面形貌参数评定方法研究

分析了当前超精密光学镜片表面评定方法及其存在的不足,提出引用ISO 25178-2中规范的部分表面3D参数来表征精密光学镜片三维表面,找出光学镜片表面形貌与对应的光学性能存在的关系,并实现ISO对超精密光学镜片三维表面的评定。仿真实验表明:当光学镜片表面的高度服从高斯分布时,其评价光学系统性能的传递函数随着均方值的减小而增大。用实例说明ISO的部分三维参数对光学镜片三维表面可以很好地区分,利用新的综合评价方法评定光学镜片表面形貌具有一定的可行性。     

Photonic crystal surface waves for optical biosensors

We present a new optical biosensor technique based on registration of dual optical s-polarized modes on a photonic crystal surface. The simultaneous registration of two optical surface waves with different evanescent depths from the same surface spot permits the segregation of the volume and the surface contributions from an analyte, while the absence of metal damping permits an increase in the propagation length of the optical surface waves and the sensitivity of the biosensor. Our technique was tested with the binding of biotin molecules to a streptavidin monolayer that has been detected with signal/noise ratio of approximately 15 at 1-s signal accumulation time. The detection limit is approximately 20 fg of the analyte on the probed spot of the surface.     

Metasurfaces Atop Metamaterials: Surface Morphology Induces Linear Dichroism in Gyroid Optical Metamaterials

Optical metamaterials offer the tantalizing possibility of creating extraordinary optical properties through the careful design and arrangement of subwavelength structural units. Gyroid‐structured optical metamaterials possess a chiral, cubic, and triply periodic bulk morphology that exhibits a redshifted effective plasma frequency. They also exhibit a strong linear dichroism, the origin of which is not yet understood. Here, the interaction of light with gold gyroid optical metamaterials is studied and a strong correlation between the surface morphology and its linear dichroism is found. The termination of the gyroid surface breaks the cubic symmetry of the bulk lattice and gives rise to the observed wavelength‐ and polarization‐dependent reflection. The results show that light couples into both localized and propagating plasmon modes associated with anisotropic surface protrusions and the gaps between such protrusions. The localized surface modes give rise to the anisotropic optical response, creating the linear dichroism. Simulated reflection spectra are highly sensitive to minute details of these surface terminations, down to the nanometer level, and can be understood with analogy to the optical properties of a 2D anisotropic metasurface atop a 3D isotropic metamaterial. This pronounced sensitivity to the subwavelength surface morphology has significant consequences for both the design and application of optical metamaterials.     

Surface polish characterization of industrial Ti: sapphire laser crystal rods by photopyroelectric scanning imaging

Photopyroelectric scanning imaging of a Ti:sapphire crystal with three different surface polishes was carried out using a novel non-contact experimental configuration. Bulk optical absorption coefficient, surface optical absorptance and theoretically normalized quadrature (Q) signal images were obtained. In addition to growth defects in the crystal, the photothermal Q images revealed variations due to the quality of surface polishes in terms of surface optical absorptance, and thermal resistance and homogeneity of each polish. Purely optical-transmission scanned images exhibited lower sensitivity to the degree of the defective state of the Ti:sapphire rod surface due to polishing. It is concluded that photopyroelectric scanning imaging can be used in the quality control of both crystal growth and surface processing of Ti:sapphire crystals.     

Measurement of the surface profile of a curved optical surface with rotation phase-shifting lateral shear cyclic path optical configuration

We present a new (to our knowledge) technique for introducing phase shifts between the laterally sheared emergent beam components of a cyclic path optical configuration (CPOC). The phase shifts are introduced by applying a small change in the angle of incidence of the incident beam due to the small angular rotation of the CPOC setup. Phase-shifting interferometry has been applied along with this phase-shifting technique for a CPOC with lateral shear to find the surface slope/profile of curved optical surfaces. Results for a spherical optical surface have been discussed. An optical setup for measurement of the surface profile of toroidal beam line mirrors of synchrotron radiation sources is proposed.     

Design of lenses with curved Petzval image surfaces

Abstract

Design strategies have been devoted to simplify and miniaturize optical systems. In this paper, by constraining image surface to coincide with the Petzval surface, we achieve a compact f/2.8 lens system design with a curved Petzval image surface. Arc distortion is proposed to accurately measure the distortion relative to a curved image surface. The optical performance of our curved image surface lens is analysed and compared. Results show that modulation transfer function (MTF) of our curved Petzval design over 69% at 100 cycles/mm for entire fields is achievable with 100-mm effective focal length, 40º full field of view, >92.4% edge relative illumination, <0.5% arc distortion. Comparisons with a traditional lens with a planar image plane demonstrate that a curved Petzval image surface is an excellent strategy to simplify and miniaturize optical systems, compensate field curvature and benefit astigmatism correction, increase off-axis illumination and improve MTF. Furthermore, the lens with a curved Petzval image surface has a more uniform optical power distribution and greater degree of lens symmetry.     

Near-field microscopy: throwing light on the nanoworld

Optical microscopy with nanoscale resolution, beyond that which is possible with conventional diffraction-limited microscopy, may be achieved by scanning a nanoantenna in close proximity to a sample surface. This review will first aim to provide an overview of the basic principles of this technique of scanning near-field optical microscopy (SNOM), before moving on to consider the most widely implemented form of this microscopy, in which the sample is illuminated through a small aperture held less than 10 nm from the sample surface for optical imaging with a resolution of ca. 50 nm. As an example of the application of this microscopy, the results of SNOM measurements of light-emitting polymer nanostructures are presented. In particular, SNOM enables the unambiguous identification of the different phases present in the nanostructures, through the local analysis of the fluorescence from the polymers. The exciting new possibilities for high-resolution optical microscopy and spectroscopy promised by apertureless SNOM techniques are also considered. Apertureless SNOM may involve local scattering of light from a sample surface by a tip, local enhancement of an optical signal by a metal tip, or the use of a fluorescent molecule or nanoparticle attached to a tip as a local optical probe of a surface. These new optical nanoprobes offer the promise of optical microscopy with true nanometre spatial resolution.     

Effect of surface roughness on determination of tissue optical properties obtained by diffusion approximation

A nylon bar with different surface roughness is used as a simulation sample of biological tissue for the determination of optical properties by using the spatially resolved steady-state diffuse reflection technique. The results obtained indicate that surface roughness has some effects on the determination of the optical properties of the nylon bar. The determined reduced scattering coefficient decreases with the decrease of the surface roughness of the nylon bar and goes to a constant for the lower surface roughness, and the determined absorption coefficient increases with the decrease of the surface roughness of the nylon bar. Consequently, the optical properties of the tissues obtained by the spatially resolved steady-state diffuse reflection technique should be modified.     

Optical anisotropy of a color-etched AZ91 magnesium alloy

In this paper, the optical anisotropy of a color-etched AZ91 magnesium alloy grain is studied. In the first part, the rinsing and drying conditions after etching were varied in order to improve the contrast between grains. A rinsing solution was selected and ellipsometric measurements were carried out to characterize the optical anisotropy of the etched surface. The wavelength, grain orientation and angle of incidence were varied. It was found that the reflection intensity at oblique incidence and the phase shift between parallel and perpendicular polarizations depend on the orientation of the etched surface of the grains. The optical contrast under diffuse light is explained by the morphology of the surface film deposited upon etching. The optical contrast under polarized light is attributed to form birefringence induced by the film texture. The birefringence, the fast axis, the slow axis, and the optical axis of the etched surface were also determined with the polarizing microscope.     

Electronically controlled surface plasmon dispersion and optical transmission through metallic hole arrays using liquid crystal

The enhanced optical properties of metal films periodically perforated with an array of sub-wavelength size holes have recently been widely studied in the field of surface plasmon optics. The ability to design the optical transmission of such nanostructures, which act as plasmonic crystals, by varying their geometrical parameters gives them great flexibility for numerous applications in photonics, opto-electronics, and sensing. Transforming these passive optical elements into devices that may be actively controlled has presented a new challenge. Here, we report on the realization of an electrically controlled nanostructured optical system based on the unique properties of surface plasmon polaritonic crystals in contact with a liquid crystal (LC) layer. We discuss the effect of LC layer modulation on the surface plasmon dispersion, the related optical transmission and the underlying mechanism. The reported effect may be used to achieve active spectral tuneability and switching in a wide range of applications.     

Gloss optical elementary representative surface

Roughness measurements are of main importance in characterizing the optical properties of papers and prints. However, there is a lack of knowledge concerning the surface size and the spacing of the measures to be optically representative of the surface structure. Paper is a multiscale medium, and the roughness parameters extracted from the three-dimensional (3D) surface mapping depend on both the size and the step of discretization. Ray tracing, based on optical geometry, could be a tool to model the light reflection on a paper surface. Ray-tracer software was therefore developed. A new optical device was used to measure paper surface topographies at various scales. Ray tracing simulations were then performed on the 3D mapping and compared to the scattering indicatrix obtained with a classical goniometer. Hence it was possible to identify a magnification for various types of paper grades that is optically representative of the specular gloss.     

温度对平晶平面度影响的定性分析及相关问题探讨

在测量平晶工作面的平面度时,温度不仅对平晶平面度的大小有影响,而且直接影响对平晶表面形状（凹凸）的判断。文章给出了温度对平晶平面度影响的实例分析,并提出了两种平晶表面形状判断的辅助方法,且对JJG28—2000《平晶》检定规程中平晶表面形状判断方法进行了必要的补充说明。     

Three-dimensional surface profiling and optical characterization of liquid microlens using a Shack-Hartmann wave front sensor

We demonstrate three-dimensional (3D) surface profiling of the water-oil interface in a tunable liquid microlens using a Shack-Hartmann wave front sensor. The principles and the optical setup for achieving 3D surface measurements are presented and a hydrogel-actuated liquid lens was measured at different focal lengths. The 3D surface profiles are then used to study the optical properties of the liquid lens. Our method of 3D surface profiling could foster the improvement of liquid lens design and fabrication, including surface treatment and aberration reduction.     

基于轴对称非球面元件的加工模型研究

轴对称非球面元件具有优良的光学性能,在现代光学系统中的应用占有越来越大的比例,对其加工质量和加工精度的高要求给光学元器件的制造业带来更大的挑战。针对轴对称非球面的精密磨削加工系统中的金刚石砂轮加工要求,提出了合理的原理方案,给出了合适的加工模型,为平面砂轮加工非球面元件提供了可行的技术方案。     

First-principles calculations of a corrugated anatase TiO2 surface

The structural, electronic and optical properties of a corrugated anatase TiO₂ surface are studied using the pseudopotential density-functional theory (DFT). The calculation of the electronic and optical properties provides the electronic and optical band gaps. The optical band gap is calculated using the photon energy dependent imaginary part of the dielectric function that indicates the exact optical transitions from occupied valence bands to unoccupied conduction bands. The estimated optical band gap is higher than the electronic band gap at the Γ point and shows consistency with the experimental band gap of an anatase TiO₂ thin-film. This result also shows the significant optical anisotropy in directions normal and parallel to the corrugated surface.     

Measurement of displacement and vibration by using the oblique ray method

An optical system that can measure vibrations and displacements is developed by using the oblique ray method. By employing a single convex lens that plays both roles of sending and receiving the beams that are reflected by the target surface, the optical measurement system became compact and reliable. A position-sensitive detector is used to measure the position change of the beam spot on the target surface. The resolution of the optical system can be controlled by changing the optical magnitude of the objective lens and is designed to be less than 0.1 microm for the developed system.     

Terahertz-Wave Antireflection Coating on Ge and GaAs with Fused Quartz

In the terahertz-wave region, fabrication of an antireflection (AR) coating is difficult because it must be as thick as several tens of micrometers, which is far thicker than that used in the optical region. We discuss a lapping method for fabricating an AR layer with a desired thickness for terahertz-wave optical devices. To demonstrate this method, we glued a thin fused-quartz plate to a surface of an undoped Ge or GaAs wafer and polished it to a thickness of one-quarter wavelength. This reduced the reflectivity of the AR surface to 1/720 of the reflection of an uncoated surface, as expected from optical theory.     

Evaluation of centricity of optical elements by using a point spread function

Our work describes a technique for testing the centricity of optical systems by using the point spread function. It is shown that a specific position of an axial object point can be found for every optical element, where the spherical aberration is either zero or minimal. If we image such a point with an optical element, then its point spread function will be almost identical to the point spread function of the diffraction-limited optical system. This consequence can be used for testing the centricity of precisely fabricated optical elements, because we can simply detect asymmetry of the point spread function, which is caused by the decentricity of the tested optical element. One can also use this method for testing optical elements in connection with a cementing process. Moreover, a simple formula is also derived for calculation of the coefficient of third-order coma, which is caused by the decentricity of the optical surface due to a tilt of the surface with respect to the optical axis, and a simple method for detecting the asymmetry of the point spread function is proposed.     

Direct evidence for surface plasmon-mediated enhanced light transmission through metallic nanohole arrays

This paper provides direct evidence for the role of surface plasmons in the enhanced optical transmission of light through metallic nanoscale hole arrays. Near-field optical images directly confirmed the presence of surface plasmons on gold nanohole arrays with interhole spacings larger than the surface plasmon wavelength. A simple interference model provides an intuitive explanation of the two types of fringe wavelengths observed in the near-field optical images. Far-field spectroscopy revealed a surface plasmon band that contributed a factor > 8 to the transmission enhancement. Furthermore, silicon nanohole arrays did not exhibit any features in the near-field, which demonstrates that metallic materials are necessary for enhanced light transmission through nanohole arrays.     

Parabolic liquid mirrors in optical shop testing

A parabolic liquid mirror obtained by the rotation of a mercury bath around a vertical axis has been built and its optical surface characteristics measured to demonstrate that it can be used in optical shop testing as a reference surface. A linear Hartmann test allowed us to check that the focal length is well related to the rotation velocity, following the theory, and that no spherical aberration is present, as assumed by previous authors. The spherical aberration has been found to be smaller than λ/50 at 633 nm. An interferometric test of the mirror compared with a null lens gave information about the quality of the optical surface for which the rms wave-front error, when the random errors are averaged, is ~λ/25. Because modifying the mirror diameter is cheap and fast and adjusting its focal length within a large range is straightforward, the parabolic liquid mirror can become a highly adaptable tool in optical metrology. In particular, it can be used in optical shop testing as a reference surface to test null correctors, to check any system developed to control the shape of large parabolic or quasiparabolic top-quality solid-state mirrors, or to make holographic references of such surfaces.