Abstract: By using an offset parabolic concave mirror as a concave mirror, and arranging a lens having an entrance pupil at the geometric focal point of the offset parabolic concave mirror, a group of rays incident parallel to the optical axis of the offset parabolic concave mirror become chief rays which are telecentric with respect to an object plane orthogonal to the optical axis of the offset parabolic concave mirror, and diverging light from each object point on the object plane can be detected on a quadric image plane formed by the lens at the focal point of the offset parabolic concave mirror without blind spots. An image of the target object is detected after the beams reflected by the offset parabolic concave mirror are bent by the reflecting mirrors and made incident on the lens to reduce the size and cost of the device.

Abstract: A spectroscope device is provided to maintain the uniformity of the central transmitting wavelength in the field of view and to minimize the broaden of the bandwidth of the transmitting wavelengths in an optical lens using an optical tunable filter (variable wavelength filter), even with a wide field of view and/or a large numerical aperture. A space is defined in which, when each beam that is incident from each off-axial object point on the object surface toward the optical lens that includes a plurality of lens elements between an object surface and a conjugate real image surface reaches the optical tunable filter, the chief ray is maintained parallel to the optical axis. Therefore, if an optical tunable filter is disposed in this space, each beam is always incident normal to the filter, so only the narrow band components at the specific central wavelength can be transmitted.

Abstract: The present invention relates to an optical device having a structure that can make the diameter of the emitted Gaussian beam smaller. The optical device is arranged between a first and second positions, and comprises a first and second optical systems separated with a focus on an intermediate position between the first and second positions. The first optical system, arranged between the first and intermediate positions, comprises a first light entrance surface on which a Gaussian beam having a beam waist, whose radius becomes w0 at the first position, is incident, and a first light emission surface from which a Gaussian beam having a beam waist, whose radius becomes w1 at the intermediate position, is emitted.

Abstract: In an incoming path, light fed to an input port is demultiplexed by a wavelength demultiplexer in terms of wavelength, converged by a first light-converging optical system, reflected by a first reflecting mirror, turned into parallel light by the first light-converging optical system, and multiplexed by the wavelength demultiplexer, so as to be fed to a reflecting surface of a rectangular reflecting mirror. In an outgoing path, the light reflected by the rectangular reflecting mirror is demultiplexed by the wavelength demultiplexer in terms of wavelengths, converged by the first light-converging optical system, reflected by the first reflecting mirror, turned into parallel light by the first light-converging optical system, and multiplexed by the wavelength demultiplexer, so as to be fed to an output port. An image of each wavelength light component reflected by the first reflecting mirror is inverted between the incoming and outgoing paths.