A method of synthesizing an effective refractive index metamaterial, the method may include the steps of: a) analysing an effective index material by directing an electromagnetic plane-wave towards a surface of the metamaterial and calculating the polarization currents distribution field in the metamaterial, wherein the effective refractive index metamaterial is comprised of a plurality of layers of at least a first material having a first refractive index and at least a second material having a second refractive index; b) filtering and sampling the polarization currents distribution field according to the layers, wherein the layers comprise pre-determined parameters requirements, the parameters including at least one of: refractive indexes of the first material and the second material, effective refractive index of the layer and thickness of the layer; and c) determining a layer arrangement and thickness for the first and second materials comprising the plurality of layers.

A method for measuring the optical quality of a given region of a glazing of a road or rail vehicle, the region being intended to be positioned in the optical path of an image-acquiring device, the measuring method being implemented by a measuring device including an emitter and a wavefront analyzer, the measuring method including emitting, with the emitter, a beam of light rays in the direction of the given region, analyzing, with the wavefront analyzer, the wavefront of the light rays transmitted by the given region, including generating a wavefront-error map, and determining, on the basis of the wavefront-error map, at least one optical-defect map, of any optical defects present in the region of the glazing.

Optical gratings, such as those used in waveguide displays, may have large aspect ratios. For example, a grating characteristic (e.g., period, feature size, etc.) can be much smaller than the grating area. Variations in the grating characteristic over the grating area may appear like a secondary grating having a long grating period superimposed on a primary grating for which the optical grating was designed. Because variations responsible for the secondary grating occur over a long distance relative to the primary grating period, it may be difficult to locate and characterize these variations with testing methods designed for shorter distances. The present disclosure presents systems and methods to detect and characterize the secondary gratings quickly and efficiently.

A performance evaluation method for a spectacle lens comprising calculating a change rate of a first component and a change rate of a second component with a computer to calculate at least one of a distortion evaluation value and a shaking evaluation value, the first component being a component in a first direction of a prism refractive index, the second component being a component in a second direction of the prism refractive index, the distortion evaluation value being a value for evaluating a distortion regarding a spectacle lens, the shaking evaluation value being a value for evaluating a shaking regarding the spectacle lens.

A lensmeter system may include a mobile device having a camera. The camera may capture a first image of a pattern through a lens that is separate from the camera, while the lens is in contact with a pattern. The mobile device may determine the size of the lens based on the first image and known features of the pattern. The camera may capture a second image of the pattern, while the lens is at an intermediate location between the camera and the pattern. The second image may be transformed to an ideal coordinate system, and processed determine a distortion of the pattern attributable to the lens. The mobile device may measure characteristics of the lens based on the distortion. Characteristics of the lens may include a spherical power, a cylinder power, and/or an astigmatism angle.

Methods for classifying a core cane of an multimode optical fiber are disclosed. In embodiments, the method includes determining a relative refractive index profile Δ(r) of the core cane; fitting the relative refractive index profile Δ(r) to an alpha profile Δ.sub.fit(r) defined by:

[00001]${\Delta }_{\mathrm{fit}}\left(r\right)={\Delta }_{o,\mathrm{fit}}\left(1-{\left(\frac{r}{a_{\mathrm{fit}}}\right)}^{{\alpha }_{\mathrm{fit}}}\right)$

where Δ.sub.o,fit is a relative refractive index at a longitudinal centerline of the core cane, α.sub.fit is a core shape parameter, and a.sub.fit is an outer radius of the core cane; generating a non-alpha residual profile Δ.sub.diff(r)=Δ(r)−Δ.sub.fit(r) for the core cane; computing one or more metrics from Δ.sub.diff(r), and using the one or metrics in a classification of the core cane, the classification comprising a prediction of whether a bandwidth at a pre-determined wavelength of an optical fiber drawn from a preform comprising the core cane exceeds a pre-determined bandwidth at the pre-determined wavelength.

Consumer products such as refraction measurement devices may be used for obtaining refraction measurements allow consumers to track their vision without visiting an optometrist or ophthalmologist. Such consumer products may work in concert with smart phones or other products having a touch screen that present images to refraction measurement devices. Smart phones may have resolution rates, sometimes measured as PPI or pixels per inch that are unknown to the user and/or refraction measurement device. One aspect of the invention is to provide an optical interface for the user to manually match the view port boundary of the smartphone to comport with the view port boundary of the refraction measurement device. Another aspect of the invention is the use of pre-distortion in images presented to the user. By noting the corrective movements exerted by the user upon the refractive measurement device, the user's own refractive error can be derived.

This method for retrieving at least one optical parameter of an ophthalmic lens comprises: obtaining an image of a first and second patterns by using an image capture device located at a first position; from that image, obtaining a first set of data from at least a part of the first pattern that is seen through the lens by the image capture device and obtaining a second set of data from at least a part of the second pattern that is seen directly i.e. outside the lens by the image capture device; retrieving the at least one optical parameter by using the first and second sets of data and taking account of relative positions of the image capture device, the lens and the first and second patterns.

A test pattern is displayed on a planar display surface 14. The power of a test lens 20 is determined by measuring the magnification of the test pattern as seen through the test lens with the test lens at two different lens distances dl.sup.1, dl.sup.2 from the display surface and calculating the power from the two magnification values and the difference in lens distance Δdl. Apparatus for carrying out the method includes a digital display screen 14 for displaying the test pattern and a digital camera 16 for capturing images of the test pattern through a test lens 20. The apparatus has a lens carriage 18 in which a test lens 20 is mounted to hold the test lens between the display screen and the camera. The lens carriage 18 is movable under control of an electronic control system 28 in a linear direction perpendicular to the display screen to vary the distance between the test lens and the display screen.

An amount obtained by multiplying a vector amount obtained by Fourier transform of a wavefront of a spectacle lens by a preset predetermined vector amount is adopted as an evaluation index of the spectacle lens, and the evaluation index is evaluated based on the evaluation index.