32 results about "Refractive measurements" patented technology

Systems for performing combined phoropter and refractive measurements to ascertain the aberrations present in the eye of a subject. The systems use a pair of phoropter wheel assemblies, one for each eye, each assembly comprising a number of lens wheels incorporating the series of lenses and wedges required to compensate for a range of refractive vision aberrations. The vision of each eye is corrected by a combination of a subjective phoropter measurement, iteratively performed with an objective wavefront analysis measurement to determine the residual aberrations existing after the initial phoropter correction. The system is able to automatically align the axes of each wavefront analyzer with is corresponding eye, by means of centering the pupil image in the wavefront analyzer camera, and to determine the pupil distance. By changing the focusing point on the wavefront analyzer of the light reflected from the eye, the corneal profile can be measured.

A viewing target for a visual acuity and refraction measurement includes at least one line comprising a width dimension that is below a resolution limit width (hereinafter “RLW”) of a test subject visual acuity, and an adjustable length dimension that is initially set at greater than the RLW of the test subject visual acuity. A base, at least approximately intersecting the line, has a thickness along the direction of the length of the line that is greater than the RLW of the test subject visual acuity. The length dimension of the line is adjustable in increments small enough to effectively approximate the visual acuity of the test subject by determining a shortest resolvable line and a next smaller line that is not resolvable by the test subject.

The invention discloses an eye diopter measurement device, the acquisition module is used to acquire the spot array image of the eye to be measured, and the first calculation module is used to calculate the horizontal vector and the vertical vector of the spot array image, which are respectively recorded as the first horizontal vector and the second A vertical vector, the second calculation module is used to construct the first matrix with the first horizontal vector and the first vertical vector, construct the second matrix with the second horizontal vector and the second vertical vector, and construct the third matrix, the third calculation module It is used to calculate the diopter of the eye to be tested according to the preset relationship satisfied by the third matrix and the diopter. The eye diopter measurement device disclosed in the present invention converts the image information into a matrix according to the obtained eye spot array image to be measured, and obtains the diopter information by calculating the matrix orthogonal transformation. Compared with the existing method, the calculation process of obtaining the eye diopter More simplified, which helps to improve measurement efficiency.

A method of precise measurement microscale refractive rate is the method of measurement the refractive of transparent and semi-transparent liquid or solid. The purpose of invention is measuring the refractive rate of transparent and semi-transparent liquid and solid medium. It accords the imaging principle of coaxial spherical optical system and measures the focal spot position of capillary with inhaling the measured liquid and gets the measured liquid's refractive rate by calculation. Select the properly capillary references according to the refractive measurement range of measured medium and then get the need of measurement precision. Example: measuring the multiple liquid medium with refractive n which is higher than 1.33 and lower than 1.48, and the standard deviation of measurement result is between 0.0002 and 0.001; the demand of sample is only 0.004ml. The sample is seal in the capillary and it is benefit to measure the microscale, toxic, irritating, effumable and inhaling liquid's refractive and also it can be used to measure the density of liquid. The invention's equipment is simple and measurement is convenience and reliable and it can be used in the research and producing department of chemical industry, medical, food, and fossil oil industry.

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.

The invention relates to a starlight atmospheric refraction measurement correction method based on collinear refraction surfaces, which is based on star vectors observed by star sensors and reference star catalogs for star map identification to obtain the matching relationship between observed stars and reference stars; The reference star vector is converted to the geographic coordinate system before entering the atmosphere to obtain the zenith distance and azimuth of the incident starlight; based on the collinear principle of the refraction surface, the imaging coordinates of all stars identified according to the star map and their azimuth before entering the atmosphere The position coordinates of the zenith direction on the imaging surface of the star sensor are obtained by optimizing the solution; according to the position coordinates of the optimal zenith direction on the imaging surface obtained by the solution, the coordinates of the image surface coordinates of all the observed stars identified are calculated using the trigonometric cosine formula Atmospheric refraction correction to obtain the corrected star coordinates; solve to obtain the attitude of the star sensor in the geographic coordinate system.