Apochromat

About: Apochromat is a research topic. Over the lifetime, 642 publications have been published within this topic receiving 7934 citations.

Objective lens, optical pickup device, and optical disc apparatus

Abstract: An objective lens is included in an optical pickup device that records and/or reproduces an information signal onto and/or from an optical recording medium. The objective lens has a numerical aperture of 0.82 or higher, has first and second surfaces that are both aspherical, and focuses a light beam onto the optical recording medium. The first and second surfaces have surface-to-surface eccentricity therebetween that causes an aberration, the aberration being correctable by tilting an optical axis of the objective lens relative to a central axis of the light beam incident on the objective lens. The aberration caused by the surface-to-surface eccentricity includes a third-order coma aberration. When the optical axis is tilted relative to the central axis of the incident light beam so that the third-order coma aberration becomes substantially 0 mλ rms, each of astigmatism, spherical aberration, and high-order coma aberration becomes 20 mλ rms or less.

Diffractive-Refractive Achromatic Lens for Optical Disk System by Glass Molding

Abstract: An erasable optical disk system requires an objective lens having minimum chromatic aberration. We estimated the chromatic aberration of a conventional refractive singlet. At shorter wavelengths, the focus shift of an objective lens exceeds its depth of focus. A diffractive-refractive hybrid lens can compensate chromatic aberration perfectly. Diffraction efficiency, however, decreases with the degree of compensation. We simulated the relationship between chromatic aberration and diffraction efficiency. Fabrication of designed lenses by glass molding was achieved, and the results showed excellent agreement with the simulation.

Single lens multispectral imaging optical system

Abstract: The invention discloses a single lens multispectral imaging optical system and belongs to the technical field of remote sensing. The system specifically comprises a multispectral apochromatic lens, a first beam splitter, a second beam splitter, a doublet lens, a visible light flat-panel detector, an infrared flat-panel detector and a laser flat-panel detector. The first beam splitter reflects visible light, and transmits infrared and laser; the second beam splitter reflects laser and transmits infrared; and the multispectral apochromatic lens, the first beam splitter and the second beam splitter are made of materials of high transmittance from the visible light to a long-wave infrared band, preferably chemical vapor deposition zinc sulfide. The function of performing multispectral imaging by using a single lens is realized, an image from the visible light to the long-wave infrared band can be obtained, and imaging performance is high; the spectrum coverage range is wide; and the system can be widely applied to the remote sensing of the fields of aerophotography, agriculture and forestry, geology and geography, hydrology and marine, and the like.

Chromatic aberration correction imaging optical system

Abstract: A chromatic aberration correction imaging optical system which has removed the chromatic aberration of the halo portion of a light flux in a specific wavelength region that passes through the peripheral edge of a lens system by providing a light shielding means for shielding a light flux in a specific wavelength region at a specified lens surface peripheral edge out of the above lens system. Accordingly, an imaging optical system which has chromatic aberration specially at a halo portion favorably corrected is provided without increasing the number of sheets of lens over a conventional imaging optical system having the same optical performance and without using an expensive special low-dispersion glass material.

Thin-lens approximation for radial gradient-index lenses

Abstract: Expressions for the Seidel aberrations of thin radial gradientindex (GRIN) lenses having a similar structure with the corresponding expressions for thin homogeneous lenses are obtained. By enabling a direct analysis of the relationship between aberrations and lens data, the thin-lens approximation provides new insight into the possibilities and limitations of aberration correction for simple optical systems using radial gradients. It is found for instance that, as in the homogeneous case, within the frame of this approximation the astigmatism of single radial GRIN lenses cannot be corrected if spherical aberration and coma are corrected or if the aperture stop is located at the lens.