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False Color Acoustic Micrographs

IP.com Disclosure Number: IPCOM000052468D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 112K

Publishing Venue

IBM

Related People

Hammer, R: AUTHOR [+2]

Abstract

This article describes a method for combining information from two or more acoustic micrographs of the same object (and the same field of view) but taken at different focal positions, into a single composite micrograph containing all of the information of the separate micrographs. Since the typical acoustic lens has high numerical aperture, the depth of focus is shallow. If a series of acoustic micrographs is taken at different depths, each micrograph will contain information primarily from that depth. By coding each of three such micrographs in the primary colors red, green and blue, a false-color composite is obtained.

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False Color Acoustic Micrographs

This article describes a method for combining information from two or more acoustic micrographs of the same object (and the same field of view) but taken at different focal positions, into a single composite micrograph containing all of the information of the separate micrographs. Since the typical acoustic lens has high numerical aperture, the depth of focus is shallow. If a series of acoustic micrographs is taken at different depths, each micrograph will contain information primarily from that depth. By coding each of three such micrographs in the primary colors red, green and blue, a false-color composite is obtained.

Each acoustic micrograph image is obtained from a black-and-white television monitor. A preferred method for accomplishing the false color overlay process is to photograph the monitor with color film using a different transparent color filter for each acoustic focal position. Alternatively, the image information can be processed by a computer and presented on a color display monitor.

At first it would seem that such a procedure should not succeed because the three colors would combine to yield an approximately white overall result. Moreover, precise registration between images is required. In the present acoustic microscope, registration is achieved using a digitally-commanded servo system. This color overlay procedure succeeds because of the phase-sensitive nature of the detector.

In acoustic microscopy utilizing piezoelectric films for detection (R.A. Lemons and C.F. Quate, Appl. Phys. Lett. 25, 251 (1974)), the output signal is sensitive to both the phase and amplitude of the reflected acoustic wave. This reflected signal shows a series of peaks and valleys as the lens-to-object spacing is varied (A. Atalar, C. F. Quate and H. K. Wickramasinghe, Appl. Phys. Lett. 31, 12,(December 15, 1977)). A logarithm of the absolute value of voltage V (Z) typical signal response as a function of lens-to-distance spacing (Z) is shown in Fig. 1. In a sample comprised of a multiplicity of layers or with layered su...