Abstract: A method and apparatus for imaging a substrate (such as silicon or silicon dioxide) beneath and between a dense array of strips (such as photoresist strips composed of dielectric or other material) using a polarizing optical microscope. In preferred embodiments, the apparatus of the invention includes a polarizer for polarizing optical illuminating radiation, an analyzer for receiving polarized radiation reflected from the sample, and a variable retarder whose retardation characteristic can be controlled to enhance the light signal transmitted through the analyzer from the substrate in a region of interest of the sample. The variable retarder can be a fixedly mounted retarder whose birefringence is variable in response to a control signal, or a rotatably mounted retarder plate having fixed birefringence which is mechanically rotatable to control the orientation of its optical axis.

Abstract: An optical recording system including a read/write optical assembly including an objective lens for reading or writing from an optical medium including a solid immersion lens disposed between the objective lens and having a surface closely spaced from the recording medium.

Abstract: A lithography system employing a solid immersion lens having a spherical surface to enhance its resolution is disclosed.

Abstract: An improved real-time confocal scanning microscope, and an improved perforated disk for use in such microscope. A preferred embodiment of the inventive microscope includes a polarizing beamsplitting cube and a rotatable Nipkow disk perforted with a hexagonal hole pattern. The disk is preferably mounted so that the scan lines produced as the disk rotates will cross both the sample feature to be imaged and the sensor array in the system's video camera at an angle substantially equal to 45 degrees. This disk orientation ensures that brightness variations caused by a non-uniform scan will not affect the measurements. Rotation of the disk is preferably synchronized with the camera frame rate to prevent any scan errors from causing random (frame to frame) variations in the camera output. The polarizing beamsplitting cube consists of two triangular prisms connected (i.e., cemented) together by a dielectric film.

Abstract: Variable focus optical system in which a light beam is projected through a transparent flat cell of electro-optic material coated on both sides with a layer of transparent conductive material. The layer on one side of the cell is divided into a central disc region and a ring shaped region which surrounds the central region. A lens focuses the light transmitted through the cell at a predetermined distance from the lens. An AC voltage is applied between one of the regions and the layer on the opposite side of the cell to vary the phase of the light passing through that region and focus that portion of the light at a distance which varies periodically with the AC voltage. A reflective surface is positioned at the distance from the lens where the unshifted light is focused, and a detector receives the light reflected from the reflective surface and provides an output signal indicative of the position of the surface.