A scanning acoustic microscope of the present invention comprises a high frequency transmitter for transmitting high frequency signal, first electric/ acoustic conversion element for converting the high frequency signal to ultrasound, acoustic lens having an end surface to which the ultrasound is incident and a concave lens surface to which the incident ultrasound is exited, an ultrasound receiver having a flat receiving surface located in an opposed relation to the concave lens surface to allow the transmission of only that ultrasound substantially vertically incident to the receiving surface, second electric/acoustic conversion element for converting ultrasound which has been transmitted through the ultrasound receiver to an electric signal, and an image processing circuit for preparing an image in accordance with a reception signal delivered from the second electric/acoustic conversion element.

A method for improving the resolution and contrast of images associated with coherent recording is presented, which includes conventional reconstruction with a reference wave followed by re-imaging the intermediately formed image through a system based on techniques from confocal microscopy. This method provides the opportunity to bring the benefits of the optical confocal microscope, namely resolution, contrast improvement, and the accompanying three-dimensional visualization, to such diverse imaging regimes as infrared, X-ray, ultraviolet, as well as other wave propagation systems such as seismic, sonar and ultrasound imaging. In addition, through snap-shot acquisition of said coherent recordings, the capability of time resolution may be added, thus adding functionality in wavelength regions where the confocal microscope currently operates.

An object of the present invention is to provide an optical system for lithography wherein the zero order component of the main lithographic image is unobstructed and the zero order component in the ghost image is removed. The optical system includes a beamsplitter component and a condensor lens structure for illuminating a lithographic mask from a range of directions which excludes a range of directions that are sufficiently close to the axis to add undesired background to the exposure field after multiple reflections with the lens. The optical system further includes an excimer laser and a lens system having an array of stops for intercepting multiple images of the excimer laser after they reflect from the primary wafer image or other surfaces such as the mask or lens surfaces. The illuminating zero-order beams reflect obliquely off the wafer after contributing to the image, where they are then refocussed to the opposite side of the pupil (the primary mirror). The beam then exits the lens towards the ghost image in an oblique fashion, and it will miss the wafer expose field entirely if the angles involved are sufficiently large. This redirection of the zero-orders is accomplished in the system with a molded fused silica fly's-eye-lens. A still further element of the system for stray light control is the use of a small stop in the pupil which blocks each zero-order beam after reflection from the wafer.