Abstract: Optical systems for routing light that reduce or eliminate polarization-dependent loss are provided. Such optical systems generally accommodate an optical element that has an intrinsic polarization-dependent loss and which is disposed to be encountered twice by the light being routed. In some instances, the optical element may be a dispersive element such as a diffraction grating or prism, but the invention has more general applicability. The optical system additionally includes both a reflective element and a wave plate assembly disposed to be encountered by the light between encounters with the dispersive element.

Abstract: Optical systems for routing light that reduce or eliminate polarization-dependent loss are provided. Such optical systems generally accommodate an optical element that has an intrinsic polarization-dependent loss and which is disposed to be encountered twice by the light being routed. In some instances, the optical element may be a dispersive element such as a diffraction grating or prism, but the invention has more general applicability. The optical system additionally includes both a reflective element and a wave plate assembly disposed to be encountered by the light between encounters with the dispersive element.

Abstract: The apparatus for detecting surface defects of a glass substrate, having a dark field optical system, includes: a first photographing device for photographing first image; a second photographing for photographing second image; a dark field illumination system disposed below the glass substrate for serving as a dark field illumination; and a detection signal processor operating coordinates of a defect position on the first image and the second image, wherein the first photographing device and the second photographing device form photographing areas in the shape of lines which are not parallel to at least the transferring direction of the glass substrate, form photographing areas for a top surface of the glass substrate to be overlapped by each other and form photographing areas for a bottom surface of the glass substrate differently from each other.

Abstract: Optical systems for routing light that reduce or eliminate polarization-dependent loss are provided. Such optical systems generally accommodate an optical element that has an intrinsic polarization-dependent loss and which is disposed to be encountered twice by the light being routed. In some instances, the optical element may be a dispersive element such as a diffraction grating or prism, but the invention has more general applicability. The optical system additionally includes both a reflective element and a wave plate assembly disposed to be encountered by the light between encounters with the dispersive element.