Abstract: An endoscope has a first end for insertion into a body, or other visually obscured area, with an optical image-forming lens device in the first end for forming two, side-by-side images of an object on opposite sides of the central axis of the endoscope. The images are transmitted to the opposite end of the endoscope, where they are received by a viewing device for three-dimensional viewing of the images by an operator. An image converging mechanism is provided in the image paths to provide a suitable convergence angle between the images at the viewing device.

Abstract: A side-viewing mirror device particularly suitable for viewing objects such as components on printed circuit boards, comprises a mirror having at least one straight edge for placing against a flat surface and a reflective front surface extending up to the straight edge, and a handle member extending at an angle less than 90 degrees to the straight edge of the mirror, so that when the straight edge is positioned against a flat surface facing the side of an object to be viewed, while viewing the object from above, the handle member will be offset out of the plane of the optical path including the mirror.

Abstract: An optical comparator in which images of a master component and a sample component are inspected by comparison of the images that are projected in a moving, abutting, merging, mirror image, a limited area of the components being viewed in a scanning illumination at a controlled rate for full viewing coverage. The components are held in a sliding tray with means for rapidly changing the component to be inspected, while maintaining precise alignment. A closely directed light source and efficient cooling device permits prolonged operation of the apparatus, and instant access to mark defective portions of the component is provided, without interrupting viewing. The location of each defective portion is marked on a reference chart for use in a viewer which provides a composite image of the chart and component in proper registration for easy identification of the faults. A marking pen is employed to mark the faults.

Abstract: Coatings particularly useful as marking inks in which an epichlorhydrin-modified polyethylenimine and an ethylene oxide-modified polyethylenimine cooperate in aqueous solution to form a composition capable of application to form deposits adherent to most materials and resistant to most organic solvents but readily removable by water.