Abstract: A novel ophthalmic lens is provided. The lens includes an astigmatism subtracting surface that removes unwanted astigmatism caused by other elements of the lens.

Abstract: The method and apparatus for measuring the transmittance of blood within a retinal vessel detects the intensity of light reflected from illuminated portions of an eye, including the retinal vessel and background fundus, and adjusts the corresponding intensity signals to compensate for reflections from the retinal vessel. In particular, the transmittance measuring method and apparatus constructs an intensity profile function based upon the intensity signals. As a result, the intensity profile function approximates the intensity of light transmitted through the retinal vessel as a function of retinal vessel position. During the construction of the intensity profile function, the transmittance measuring method and apparatus can compensate for at least some of the reflections of light from the retinal vessel which occurred prior to propagation of the light through the retinal vessel, thereby increasing the accuracy with which the transmittance of blood within a retinal vessel is measured.

Abstract: The method and apparatus for measuring the oxygen saturation of blood within a retinal vessel illuminates the retinal vessel with light having a combination of wavelengths selected to reduce the error in the measured blood oxygen saturation. The oxygen saturation measuring method and apparatus illuminates a retinal vessel with light having the selected combination of wavelengths. For example, the oxygen saturation measuring method and apparatus can illuminate the retinal vessel with light having a first wavelength between 460 nm and 503 nm, a second wavelength between 600 nm, and 770 nm and a third wavelength between 770 nm and 1000 nm. The oxygen saturation measuring method and apparatus then measures the transmittance of the blood within the retinal vessel in response to the illumination at each of the selected wavelengths.

Abstract: An infrared spectropolarimeter system for making spectroscopic measurements of electro-optic properties of materials over a large wavelength range in the infrared is described which comprises in combination a spectrometer having a sample region for receiving a sample for making spectroscopic measurements thereon and a source of light for providing a sample beam of selected wavelength for projection through the sample region, the sample region defined between a first focusing element for selectively focusing the sample beam within the sample region and a second focusing element for collimating the sample beam and providing an output beam for analysis, first and second polarizers between the focusing elements with the sample region therebetween for selectively polarizing the sample beam, first and second rotatable optical retarders between the polarizers with the sample region therebetween for selectively retarding one linear polarization component with respect to the orthogonal component of the sample beam, an

Abstract: An infrared achromatic waveplate structure having a cadmium sulfide (CdS) plate and a cadmium selenide (CdSe) plate aligned with each other so that the fast axis of the plates are perpendicular to each other, this structure provides a desired retardance of a first orthogonal polarization component with respect to a second orthogonal polarization component of an incident light beam. The thickness of the plates are in a ratio between 0.8:1 and 0.9:1 (CdSe:CdS), an achromatic response with a substantially constant retardance is provided in a wavelength range from 3 to 11 microns. A desired amount of retardance is available by adjusting the thickness of the two plates as long as the ratio of the thicknesses is maintained within the recited value. In particular a quarter wave net retardance of an incident light beam operating between 3 and 11 microns is provided when the cadmium sulfide plate is 1.25 millimeters and the cadmium selenide plate is 1.0666 millimeters.

Abstract: A multicomponent quantitative analytical method and apparatus wherein the method includes the steps of and the apparatus is capable of performing steps of obtaining a plurality of calibration spectra, transforming the calibration spectra using a transform with orthogonal basis vectors, obtaining a calibration matrix relating the transform spectra to concentrations of analytes in the calibration samples, obtaining a spectrum for an unknown sample, transforming the unknown sample spectrum, and relating the transformed unknown sample spectrum to the calibration matrix to thereby determine the concentration of analytes in the unknown sample.