A photometer for use with a microscope having an object plane an image plane and an optical axis between said planes. The photometer includes an optical dividing means adapted to be disposed in the optical axis between the microscope object and image planes, and a reflective element having a reflecting surface. A pin hole occluder is adapted to be arranged on the opposite side of the optical dividing means to the reflective element. An optical imaging device provides an image of the pin hole occluder on the reflecting surface. A semi-reflective element is provided for reflecting light from the light source to the optical dividing means. A detector is arranged in an optical axis including the semi-reflective element, the pin hole occluder, the optical dividing means, the optical imaging device and reflective element. The object and image planes of the microscope and the reflecting surface of the reflective element are conjugate planes, so that further information additional to the pin hole occluder can be imaged into the microscope image plane.

High contrast silhouette images of a substantially opaque object are obtained using front illumination techniques. The object is frontally illuminated by light of a first polarization. A frontal surface of the object reflects the incident light to an observation station. The polarization of incident light bypassing the object and incident on a background is changed. The background light is reflected to the observation station, and the intensity of one of the two, differently polarized, reflected images is substantially reduced with respect to the other. Apparatus for carrying out the method includes a first polarizer for polarizing frontally incident illuminating light, a second polarizer behind the object and a reflective surface behind the second polarizer. A polarization analyzer, located in front of the object, is used to extinguish one of the two reflected images. Apparatus for carrying out the invention in instruments having a polarized light source and a polarization analyzer includes a combination of a polarizing material, for contacting a rear surface of the object, and a reflective surface provided adjacent the rear surface of the polarizing material. The combination is applied to the rear surface of the object. Back-surface mirrors of pleochroic substrates applied to thin film physical vapor deposited electronic circuit elements enable front lighted shadowgraphic imaging of the elements.

In microscopes having a photometer device disposed at or in an intermediate tube, wherein the tube is provided on one of its ends, or in the proximity thereof, at the underside with a coupling device for attachment to the stand and, on the opposite side, with a coupling device for the attachment of an ocular, the improvement comprising inserting the photometer, via a beam splitter, a tripple mirror connected thereafter, as well as an ocular, into the light flux of the intermediate tube. Other improvements disclosed are optical means provided in or at the intermediate tube or photometer, for introducing a beam path imaging measuring values and/or characteristic data and, an adjustable intensity regulator for the optical means.

In an alignment mark detecting optical system usable with an automatic alignment apparatus wherein alignment marks of a wafer and a mask are scanned by a laser beam to detect the state of misalignment therebetween, the laser beam scans the surface of the wafer opposed to the mask and the surface of the mask opposed to the wafer, i.e., the front face of the wafer and the back face of the mask. The light beams reflected by the surfaces are introduced to one or more photodetectors.

Projection lenses and projection lens systems are telecentric between an illumination subsystem and a set of imagers. The lenses and systems can exhibit color fringing correction, uniform imager illumination, athermalization, and component articulation for improved imaging. The lenses and systems may be employed in display apparatuses, such as folded display apparatuses that have decreased footprint size, but long effective projection lengths.