Off-axis Lens Research Articles

Polariton Microfluidics for Nonreciprocal Dragging and Reconfigurable Shaping of Polaritons.

Dielectric environment engineering is an efficient and general approach to manipulating polaritons. Liquids serving as the surrounding media of polaritons have been used to shift polariton dispersions and tailor polariton wavefronts. However, those liquid-based methods have so far been limited to their static states, not fully unleashing the promise offered by the mobility of liquids. Here, we propose a microfluidic strategy for polariton manipulation by merging polaritonics with microfluidics. The diffusion of fluids causes gradient refractive indices over microchannels, which breaks the symmetry of polariton dispersions and realizes the microfluidic analogue to nonreciprocal polariton dragging. Based on polariton microfluidics, we also designed a set of on-chip polaritonic elements to actively shape polaritons, including planar lenses, off-axis lenses, Janus lenses, bends, and splitters. Our strategy expands the toolkit for the manipulation of polaritons at the subwavelength scale and possesses potential in the fields of polariton biochemistry and molecular sensing.

Modelling eye lengths and refractions in the periphery.

To create a simplified model of the eye by which we can specify a key optical characteristic of the crystalline lens, namely its power. Cycloplegic refraction and axial length were obtained in 60 eyes of 30 healthy subjects at eccentricities spanning 40° nasal to 40° temporal and were fitted with a three-dimensional parabolic model. Keratometric values and geometric distances to the cornea, lens and retina from 45 eyes supplied a numerical ray tracing model. Posterior lens curvature (PLC) was found by optimising the refractive data using a fixed lens equivalent refractive index ( ). Then, was found using a fixed PLC. Eccentric refractive errors were relatively hyperopic in eyes with central refractions ≤-1.44 D but relatively myopic in emmetropes and hyperopes. Posterior lens power, which cannot be measured directly, was derived from the optimised model lens. There was a weak, negative association between derived PLC and central spherical equivalent refraction. Regardless of refractive error, the posterior retinal curvature remained fixed. By combining both on- and off-axis refractions and eye length measurements, this simplified model enabled the specification of posterior lens power and captured off-axis lenticular characteristics. The broad distribution in off-axis lens power represents a notable contrast to the relative stability of retinal curvature.

In-line and off-axis polarization-selective holographic lenses recorded in azopolymer thin films via polarization holography and polarization multiplexing.

Polarization-selective diffractive in-line and off-axis lenses are recorded in azopolymer thin films using polarization holography. A simple, yet efficient, and to the best of our knowledge, new method is used to suppress the surface relief grating formation and to improve the polarization properties of the lenses. The in-line lenses are converging for right circularly polarized (RCP) light and diverging for left circularly polarized (LCP) light. Bifocal off-axis lenses are recorded by polarization multiplexing. By rotating the sample at 90° between the exposures, the two focal points of these lenses are located in orthogonal directions O x and O y, so we can refer to these novel lenses as 2D bifocal polarization holographic lenses. The light intensity in their focuses depends on the reconstructing light polarization. According to the recording scheme, they can either reach maximum intensities simultaneously (for LCP or RCP), or alternatively, one of them can be at maximum for LCP, while the other for RCP. These lenses may be used as polarization controllable optical switches, in the field of self-interference incoherent digital holography or for other photonics applications.

Optical spectrograph for the Takhomag-International Space Station space-based spectromagnetograph

Subject of study. This paper is the second part of a series devoted to the development of the optical spectrograph designed for the Takhomag-International Space Station space-based spectromagnetograph planned to be deployed in the Russian segment of the International Space Station. The first paper of the series published in this journal describes a solar optical telescope in the spectromagnetograph. Aim of study. This study aimed to design an optical spectrograph for the Takhomag-International Space Station spectromagnetograph with properties required for the measurement of the Zeeman effect at selected spectral lines under magnetic fields characteristic of the solar photosphere. Method. The design of the Takhomag-International Space Station spectrograph is a classic variation of the off-axis lens scheme of the Littrow spectrograph. FeI 6301.5 Å and FeI 6302.5 Å lines were chosen as working spectral lines. The lens-based spectrograph design enabled it to satisfy the requirements of its limited size without optical elements with aspherical surface shapes. Main results. Despite the hard constraints on mass and dimensions owing to the conditions of operation, the spectrograph enables the formation of almost aberrationless images (Marechal parameter exceeding λ/20) of the solar photosphere spectrum with an angular resolution of 0.35″ by the Rayleigh criterion that corresponds to the angular resolution of the solar optical telescope of the Takhomag-International Space Station spectromagnetograph with a spectral range of 2.52 Å and spectral resolution of approximately 30 mÅ. The spectral resolution is smaller than the widths of the spectral lines used in the range of 42.4 mÅ in intense spots to 49.1 mÅ in a calm photosphere that results from the chaotic motion of atoms along the line of sight and the unresolvable structure of microturbulent velocities. Practical significance. The development of the Takhomag-International Space Station spectromagnetograph will facilitate the solution of relevant problems of solar and plasma physics and provide the groundwork for preparing more complex missions involving solar research from small distances.

Study on a plane grating spectral imaging system with smile and keystone eliminated

Subject of study. For a grating-based imaging spectrometer, a method of using an off-axis lens to correct the smile and keystone is proposed and verified by simulation. Method. In the set coordinate system, the ratios of direction cosines of the refractive rays along the y-axis and z-axis are studied using the spatial ray tracing method. On this basis, the smile characteristics of a single refraction sphere and an off-axis lens have been analyzed. In order to verify the theory, a visible spectral imaging system without an off-axis lens and one with an off-axis lens have been optimized, respectively. Main results. The criterion of the smile sign has been given and discussed. For the spectral imaging system without an off-axis lens, good image quality and high spectral resolution have been achieved, which is less than 1 nm. The modulation transfer functions at the wavelengths of 400, 600, and 800 nm are greater than 0.5 at the Nyquist frequency. However, the maximums of the smile and keystone are greater than 0.07 and 0.06 mm, respectively, which are several times the unit size. For the spectral imaging system with an off-axis lens, the image quality is basically the same as the previous one. The obvious differences between the two systems are the smile and keystone. For the latter, the maximums of smile and keystone at all working wavelengths in all fields are close to 6.24 and 6.40 µm, which are less than half of the unit size. Practical significance. The smile and keystone caused by a plane grating can be corrected by an off-axis lens in a plane-grating-based imaging spectrometer, which provides a universal method for the design of a spectral imaging system.

Standing wave polarization holography for realizing liquid crystal Pancharatnum-Berry phase lenses.

A standing wave polarization holography setup is proposed to generate the desired polarization field for fabricating both on-axis and off-axis liquid crystal Pancharatnum-Berry phase lenses. Compared to other interference exposure setups, standing wave interferometry can double the polarization field amplitude because it does not require a beam splitter. Moreover, the optical axis angle of the lenses can be easily adjusted without realigning the optical setup. Based on the design, we first theoretically derive the polarization field distribution. In the experiment, we build the recording optical system and fabricate a series of on-axis and off-axis lenses. Further optical characterization proves the high diffraction efficiency of the fabricated lenses.

Facile large-area uniform photolithography of membrane diffractive lens based on vacuum assisted self contact method

Optical polyimide (PI) membrane is a promising substrate material for diffractive lens applied in future large-aperture space based imaging system because of its light weight, environmental adaptability and deployable feature. In this letter, we put forward a facile large-area uniform photolithography technique using vacuum assisted self contact method to fabricate large-aperture membrane diffractive lens. We fabricated a φ 400 mm aperture membrane off-axis 2-levels Fresnel Zone Lens (FZL) based on the method and achieved uniformly distributed photoresist morphology as well as over 36.6% average diffraction efficiency in full aperture. The results demonstrated that vacuum assisted self contact method effectively eliminates considerable air gaps caused by unevenness of large area photomask and substrate, thus facilitates uniform light field distribution in photoresist. This work provides reference to fabrication techniques of large aperture membrane diffractive lens, and offers feasible methods for future large area flexible electronics manufacturing.

Peripheral Defocus of the Monkey Crystalline Lens With Accommodation in a Lens Stretcher.

PurposeTo characterize the peripheral defocus of the monkey crystalline lens and its changes with accommodation.MethodsExperiments were performed on 15 lenses from 11 cynomolgus monkey eyes (age: 3.8–12.4 years, postmortem time: 33.5 ± 15.3 hours). The tissue was mounted in a motorized lens stretcher to allow for measurements of the lens in the accommodated (unstretched) and unaccommodated (stretched) states. A custom-built combined laser ray tracing and optical coherence tomography system was used to measure the paraxial on-axis and off-axis lens power for delivery angles ranging from −20° to +20° (in air). For each delivery angle, peripheral defocus was quantified as the difference between paraxial off-axis and on-axis power. The peripheral defocus of the lens was compared in the unstretched and stretched states.ResultsOn average, the paraxial on-axis lens power was 52.0 ± 3.4 D in the unstretched state and 32.5 ± 5.1 D in the stretched state. In both states, the lens power increased with increasing delivery angle. From 0° to +20°, the relative peripheral lens power increased by 10.7 ± 1.4 D in the unstretched state and 7.5 ± 1.6 D in the stretched state. The change in field curvature with accommodation was statistically significant (P < 0.001), indicating that the unstretched (accommodated) lens has greater curvature or relative peripheral power.ConclusionsThe cynomolgus monkey lens has significant accommodation-dependent curvature of field, which suggests that the lens asserts a significant contribution to the peripheral optical performance of the eye that also varies with the state of accommodation.

Multifunctional metasurface: from extraordinary optical transmission to extraordinary optical diffraction in a single structure

We show that, a metasurface composed of subwavelength metallic slit array embedded in an asymmetric environment can exhibit either extraordinary optical transmission (EOT) or extraordinary optical diffraction (EOD). By employing an analytical model expansion method and the diffraction order chart in k-vector space, we found that the resonance decaying pathway of the local slit cavity mode can be tuned to either 0th or -1st diffraction order by changing the parallel wavevector, which gives rise to enhanced 0th transmission (EOT) of the structure for small incident angles, and enhanced -1st diffraction (EOD) for large incident angles. Based on this appealing feature, a multifunctional metasurface that can switch its functionality between transmission filter, mirror and off-axis lens is demonstrated. Our findings provide a convenient way to construct multifunctional integrated optical devices on a single planar device.

高精度离轴非球面透镜的制造与检测

高精度离轴非球面透镜的制造与检测

Development and testing of low spatial frequency holographic concentrator elements for collection of solar energy

Abstract The aim of this research is to use holographically recorded diffractive optical elements (DOEs) recorded in photopolymer in order to effectively collect and concentrate solar radiation. The potential for recording high diffraction efficiency DOEs with a large angular and wavelength range of operation in acrylamide based photopolymer and the optimum recording conditions have been presented in our previous work (Akbari et al., 2014b, 2014a). Theoretical modelling and experimental test are presented which demonstrate that low spatial frequency components, around 300 line pairs/mm, have an appropriate spectral bandwidth, high efficiency and very limited polarization dependence. Pairs of concentrating off-axis lenses are fabricated in photopolymer and arranged to concentrate light on a c-Si cell. The optical recording process is described and discussed. The results from electrical characterization confirm that with the (two) spherical DOEs (each of area 113 mm 2 ) in place, the output current of c-Si solar cells is approximately doubled for the solar cells with area of 12 mm 2 .

Study on imaging spectrometer with smile and keystone eliminated

The formulas of image height in two-dimensional field about Gaussian and tilted imaging system of grating-based imaging spectrometer instrument (GISI) are deduced firstly, and the determined expressions of smile and keystone of GISI are obtained. It is proposed to correct the smile with off-axis lens, and the elimination effect of the smile is studied by means of spatial ray tracing. By controlling the degree of off-axis and the distribution of focal power of the off-axis lens, the long-wave infrared imaging spectrometer with well-eliminated smile and keystone is designed. The maximum of smile and keystone at working wavelengths in all fields of view are less than 8.57µm and 13.33µm, respectively.

Scalable screen-size enlargement by multi-channel viewing-zone scanning holography.

Viewing-zone scanning holographic displays can enlarge both the screen size and the viewing zone. However, limitations exist in the screen size enlargement process even if the viewing zone is effectively enlarged. This study proposes a multi-channel viewing-zone scanning holographic display comprising multiple projection systems and a planar scanner to enable the scalable enlargement of the screen size. Each projection system produces an enlarged image of the screen of a MEMS spatial light modulator. The multiple enlarged images produced by the multiple projection systems are seamlessly tiled on the planar scanner. This screen size enlargement process reduces the viewing zones of the projection systems, which are horizontally scanned by the planar scanner comprising a rotating off-axis lens and a vertical diffuser to enlarge the viewing zone. A screen size of 7.4 in. and a viewing-zone angle of 43.0° are demonstrated.

消谱线弯曲长波红外成像光谱仪设计

To achieve the long-wave infrared hyperspectral imaging for remote sensing targets and to eliminate the spectral curvature of a plane grating effectively, a long-wave infrared imaging spectrometer with an off-axis lens was designed. The spectral curvatures from the plane grating and a single off-axis lens were calculated, respectively, and the relationships between spectral curvatures and relative parameters were analyzed, then an initial structure for eliminating spectral curvature was designed. The optical system optimized shows an aperture of 100 mm, F number of 2, spectral resolution of 20 nm, spatial resolution of 150 rad, and a cold aperture efficiency of 100%. Moreover, its image quality is close to the diffraction limit and the spectral curvature of system changes from more than 180 m to less than 14.3 m. The design obtains a universal eliminating spectral curvature formula, and proves that the off-axis lens has the function to eliminate spectral curvature. It concludes that the imaging spectrometer of plane grating using off-axis lens can offer a spectral curvature less than half the pixel size of the detector without increasing the system complexity, which meets the use request on the premise of satisfying imaging quality.

Thermal optical path difference analysis of off-axis lens ray trace foot-print

The optical system lens temperature difference will cause optical aberration increase. This study is applying finite element method (FEM) and optical ray tracing; calculate off axis ray thermal optical path difference (OPD). The optical system temperature distribution is calculated from finite element simulation result and weighting temperature to each optical ray path. The simulation result shows off-axis ray major thermal optical aberrations are tilt and piston at this study.

Table screen 360-degree three-dimensional display using a small array of high-speed projectors

We propose a 360-degree three-dimensional display with a table screen, which consists of a small number of high-speed projectors and a rotating screen. Because each high-speed projector is located outside the rotating axis of the screen, multiple projectors can be aligned. The lens shift technique is used to superimpose multiple images generated by all projectors on the rotating screen. The screen has an off-axis lens function such that the rotation of the screen generates numerous viewing points on a circle. The use of multiple projectors enables an increase in the number of colors, an increase in the number of viewing points, and a reduction in the screen rotation speed. We develop an image synthesis technique for the proposed display system. A color display system employing three high-speed projectors is demonstrated.

计算全息法检测离轴凸非球面照明镜组初始结构设计

计算全息法检测离轴凸非球面照明镜组初始结构设计

An evaluation of a novel instrument for measuring macular pigment optical density: the MPS 9000

Of the antioxidants found in the human retina, only the macular carotenoid quantities can be estimated noninvasively (albeit in a collective fashion), thus facilitating study of their role in that tissue. The aim of this study was to evaluate concordance between macular pigment optical density (MPOD) values recorded on a commercially available instrument, the MPS 9000, with those of an already validated heterochromatic flicker photometry instrument. Also, we assessed and compared test-retest variability for each instrument. Macular pigment optical density at 0.5 retinal eccentricity was measured using two different heterochromatic flicker photometers, the MPS 9000 and the Macular Densitometer(TM), in 39 healthy subjects. Test-retest variability was evaluated separately for each instrument by taking three readings over a 1-week period in 25 subjects. There was a moderate positive correlation for MPOD at 0.5° of retinal eccentricity between the MPS 9000 and the Macular Densitometer described by the linear equation y = 0.763x + 0.172 (r = 0.68, p < 0.001, r(2) = 0.46); however, a paired-samples t-test showed a significant difference in terms of mean values, with a bias of lower MPOD values being yielded by the MPS 9000 (t = -4.103, p < 0.001). Bland-Altman analysis indicated only moderate agreement between the two instruments, reflected in 95% limits of agreement of 0.1 ± 0.27. Inter-sessional repeatability, expressed as a coefficient of repeatability, ranged from 0.18 to 0.21 [mean (±SD): 0.19 (0.02)] for the MPS 9000 and from 0.11 to 0.12 [mean (±SD): 0.12 (0.01)] for the Macular Densitometer. The results demonstrate that the MPS 9000 consistently yields MPOD readings, which are lower than that found with the Macular Densitometer, and exhibits substantial test-retest variability.

短波红外棱镜-光栅-棱镜成像光谱仪光学系统设计

An optical system for short wave infrared imaging spectrometer was proposed based on prism-grating-prism(PGP)component.The system is composed by off-axis TMA,collimator,PGP and re-imaging lens,and its response covers the range 950 to 2 500 nm with a 22.5°field of view.The system is able to achieve wide field and broadband.By optimizing the PGP paramters and tilting the reimaging lens along the spectral dimenstion,keystone and smile became slight and were even less than 5 micrometer.Thus the obtained spectral data were more exact.

Shack-Hartmann sensor based on a low-aperture off-axis diffraction lens array

A Shack-Hartmann type wavefront sensor designed on the basis of a low-aperture off-axis diffraction lens array is described. Tests experiments showed that the sensor is capable of measuring wavefront slopes at array subapertures of size 640×640 µm with an error not exceeding 4.80 arcseconds (0.15 pixel), which corresponds to the standard deviation (SD) (SD = 0.0170λ) at the reconstructed wavefront. Advantages of the array used in the sensor and the technology of its manufacture are discussed. The sensor tested in the experiments can be used to measure atmospheric turbulence parameters and as an element of adaptive optical imaging systems.