Abstract: An optical system includes: a lens group having an optical axis, a focal length of a first light, and a focal length of a second light; and a light splitter disposed at rear side of the lens group and splitting the first light and the second light incident from the lens group respectively, to guide the first light onto first imaging position and guide the second light onto second imaging position. The lens group includes lens elements transmitting the first light and the second light to match the first imaging position with the focal length of the first light and match the second imaging position with the focal length of the second light separately from the first imaging position. The lens element of the lens group is provided in front side of the light splitter with no lens element being provided in the rear side of the light splitter.

Abstract: There is provided a method for manufacturing a method for manufacturing an optical element, wherein a mold-press molding is performed by use of a material body having a prismatic shape to form a light transmission part and a flange of the optical element, the flange extending outward from the light transmission part. In the manufacturing method, only a corner of the material body to be subjected to a mold transfer to provide an edge face of the flange.

Abstract: Pulsed laser beams are applied to an object to be measured. A first laser beam of a pulsed laser beam having a first wavelength which is oscillated immediately after the rise of the pulsed laser beam, and a second laser beam having a second wavelength which is oscillated thereafter are used. Based on a difference between an intensity of first interfered light of reflected light of the first laser beam or transmitted light thereof, and an intensity of reflected light of the second laser beam or transmitted light thereof, temperatures of the object to be measured, and whether the temperatures are on increase or on decrease are judged. The method and device can be realized by simple structures and can measure a direction of changes of the physical quantities.

Abstract: Pulsed laser beams are applied to an object to be measured. A first laser beam of a pulsed laser beam having a first wavelength which is oscillated immediately after the rise of the pulsed laser beam, and a second laser beam having a second wavelength which is oscillated thereafter are used. Based on a difference between an intensity of first interfered light of reflected light of the first laser beam or transmitted light thereof, and an intensity of reflected light of the second laser beam or transmitted light thereof, temperatures of the object to be measured, and whether the temperatures are on increase or on decrease are judged. The method and device can be realized by simple structures and can measure a direction of changes of the physical quantities.

Abstract: An air bag which is inflated simultaneously or almost simultaneously as a whole to be above to receive a human body quite securely, which is made up on non-expandable cloth as a whole, and which has a shape at inflation wherein both side portions of a central surface facing a human body are projected forward more than the surface facing a human body is projected.