Yasufumi Emori

The Multi-Purpose Camera: A New Anterior Eye Segment Analysis System

A new device for the analysis of the anterior eye segment was developed. With this device, a Scheimpflug slit image and a retroillumination image can be taken separately using a CCD camera. The quality of the images obtained was satisfactory enough for analysis. The data obtained were stored and analyzed on an almost real-time level using an on-line computer. The menu for the data analysis provided for this device includes multilinear densitometry, with planimetry, area densitometry, measurement of anterior chamber depth and thickness of lens layers, determination of chamber angle and positioning of implanted intraocular lenses, and measurement of opaque areas in the retroillumination image.

Measurement of postoperative intraocular lens tilting and decentration using Scheimpflug images

ABSTRACT A three‐dimensional, in vivo method for determining the position of implanted intraocular lenses (IOLs) using an image‐processing technique has been developed. Two images of the anterior segment of the eye with an implanted IOL were photographed with a Scheimpflug camera at slitlamp angles of 90 degrees and 180 degrees. After geometrical correction, the contours of the original images were enhanced using binarization and curve‐fitting techniques. These images afforded calculation of the angle of tilt of the IOL optic axis relative to a standard reference line which connected the center of anterior corneal surface curvature with the geometrical center of the pupil. The extent and direction of IOL decentration could also be shown. The IOL image in the posterior chamber was expressed as a wire‐frame figure. This method provides several kinds of biometry in pseudophakic eyes.

Laboratory measurement of diffuse spectral reflectance and transmittance of some natural objects in the near-infrared.

SummaryLaboratory measurement of diffuse spectral reflectance in the region from 0.4 to 2.5 μ was carried out for several kinds of materials like sand, concrete, white marble and brick. The diffuse reflectance of a leaf of several kinds of vegetables was also investigated. A method, although it is indirect, was intended to measure the diffuse spectral transmission of a thin skin such as a leaf. The intensities of both reflection and transmission of a leaf are low in the visible region, but increase remarkably in the near-infrared region. The water absorption bands become important with increasing wavelength.ZusammenfassungDas spektrale diffuse Reflexionsvermögen im Wellenlängenbereich 0,4 bis 2,5 μ wurde für verschiedene Oberflächen, wie Sand, Beton, weißen Marmor und Ziegel, gemessen. Ebenso wurde das diffuse Reflexionsvermögen eines Blattes verschiedener Gemüsearten untersucht. Ein anderes, indirektes Verfahren erlaubt die Messung des spektralen diffusen Transmissionsvermögens eines dünnen Gegenstandes, z. B. eines Blattes. Reflexions- und Transmissionsvermögen eines Blattes sind klein im sichtbaren Wellenlängenbereich, nehmen jedoch im nahen Infrarot stark zu. Mit zunehmender Wellenlänge erlangen die Absorptionsbanden des Wassers Bedeutung.

Polarization Effects in Holography

The polarization characteristics of phase holograms are obtained in various spatial frequencies. These characteristics are evaluated by measurements of the diffraction efficiencies for the reconstructing beam, whose electric vector is parallel and perpendicular to the plane containing the reference and object beams, respectively.

Design of Optimal LUT in Color-Reproduction of Dots Printer

Recently, digital hard copy machines have drawn a great attention because they have good performance of signal processing. Hard copies are directly obtained from video signal by connecting CRT monitor and digital hard copy machine. At that time, many signal processing are considered to produce the desired images. In the color reproduction process, the processing technique that can reproduce saturated and luminous color of CRT monitor by using color ink must be considered, because the color gamut of CRT color monitor is wider than the one that uses in ink for printing purpose. This paper proposes a method of color rearrangment along the constant hue locus to produce correctly the hue of the colors that exist between the ink gamut and CRT gamut. And then, it is shown that the effect is observed clearly in red comparing to the usual color rearrangment.

Optical design of airborne imaging spectrometer

Optical design of Air.bone liaging Spectroieter is described in this study. A new design of push.brooi type liaging Spectroseter using lens, prisa and CCD sensor systei is cospared to classical Isaging Spectrometers those were composed of all reflecting optical components. Advantage of using refracting elements against that of using mirror and reflection grating is the design flexibility of optical components and possibility of reducing and correcting many kind of aberrations. Disadvantage of lens system - chromatic aberration - is reduced to be negligibly small within 0.4 to 1.0 jim by selecting glass materials. The purpose of Imaging pectrometer is to monitor life conditions of vegetations from high altitudes by measuring spectral reflectance of foliage (chiorophyl). By such purpose, wavelength was limited from visible until near IR region.

An Optical Approach For The Observation Of Nuclear Fuel Failure Phenomenon In A Water Environment

A great effort has been made to develop an experimental apparatus by optical method to observe phenomena of nuclear fuel failure in a water environment in actual in-reactor experiments. There are many difficulties to be overcome, such as high radiation fluence, limited space, shock pressure generation, fission products release. It was extracted through irradiation tests of glasses, fibers and films that non-browning glass used periscope should be recommended as, an image guide, and light is hardly guided effectively from outside source into a capsule by optical fibers or a periscope. On the other hand, ex-reactor simulation tests were successfully carried out to record photographically the transient behaviour on the surface of a heated rod by a high speed camera through a periscope with a lamp immersed directly into water in a capsule. Based on the results of these tests, an experimental apparatus for in-reactor tests was designed to observe transient behaviour of a fuel rod including fuel failure and subsequent phenomena.

Feasibility of Discriminating Tree Species and Tree Vigor by Chromaticity of Color Infrared Photography

The feasibility of the tree species discrimination and tree vigor discrimination were examined by using of Chromaticity measurement of IR color film.The chromaticity of color image was determined from measuring spectral transmit-tance by the microspectrophotometer, and displaied on the CIE 1960 UCS diagram.Discrimination was based on the differences of the chromaticities, and discriminant functions to discriminate tree species were obtained.The result shows that discrimination of tree species is relatively easy in the case of some tree combination, and that discrimination of the tree vigor gradation is not feasible, by the chromaticity measurements.