In a light beam scanning type recording system in which a part of a read-out light beam scans a form slide and another part of the read-out light beam scans a linear encoder to generate photoelectric pulses, a data signal is read out by use of a video clock signal, and a recording light beam is modulated by a video signal obtained by combination of the data signal and the form signal, a device for correcting displacement of the form slide from a predetermined position with respect to the data information is provided. An optical mark is provided on the form slide in the marginal area thereof and a mark signal is generated when the read-out light beam passes through the optical mark. The number of clock pulses from a pulse generator is counted after the mark signal is generated and before the first photoelectric pulse is outputed to detect the amount of displacement of the form slide. Then, the video clock signal or the form signal is delayed according to the detected amount of displacement.
A multi-wavelength optical apparatus for laser processing, alignment and observation employs dichroic mirrors, which, by virtue of their wavelength characteristics, affect a processing laser beam differently from alignment and observation light. A projection optical system and a dichroic mirror form first and second images of an aperture on an object disposed on a movable stage from processing light and alignment light, respectively. The position of the second image relative to a reference is determined and automatically provides the position of the first image relative to the reference. The apparatus is used to repair microdefects in semiconductor circuit elements, for example.
A deep-UV step-and-repeat photolithography system includes a narrow-bandwidth pulsed excimer laser illumination source and an all-fused-silica lens assembly. The system is capable of line definition at the 0.5-micrometer level. One significant feature of the system is its ability to perform wafer focus tracking by simply changing the frequency of the laser.
A projector slide has eight possible orientations, only one of which is the correct one to project a properly oriented image. For an automatic orientator to work there must be a simple way to recognize any one of the eight orientations and decide how to place the slide in the correct orientation. A method and device is described here which accomplishes this task.
