Abstract: Method and apparatus useful in the inspection of a target comprises scanning the target with a pulsed acoustic beam, sensing the pulsed beam after it has been modified by interaction with the target, producing a time-domain signal indicative of the modifications, processing the time-domain signal to produce a frequency domain representation of the modifications, and producing an image-wise display of the frequency domain representation of the modifications. In one execution disclosed, the frequency domain representation is altered and then reconverted to a time domain signal before display.

Abstract: An improved tray-scanning station for a tray-fed scanning acoustic microscope prevents the dislodging of small, loosely held parts from the trays by coupling fluid as the trays pass through an inspection station, or by the action of a dryer as the trays pass through a drying station.

Abstract: A method and apparatus for non-destructive ultrasonic inspection in which a plurality of integrated circuits or other electronic components laid out in a fixed pattern on a liquid-permeable tray are moved along an inspection path through a scanning station. In the scanning station the electronic components are repetitively scanned by an ultrasonic beam from a transmitter/receiver moving rapidly back and forth across the inspection path; an ultrasonic coupling liquid (usually water) continuously flows along the beam path; the coupling liquid also flows along the surfaces of the electronic components opposite the beam path. The tray of electronic components is air dried as it emerges from the scanning station. Both reflected and "through" ultrasonic signals can be collected to disclose any anomalies present in the electronic components. A screen may be used to assure retention of the electronic components in the desired pattern on a tray.

Abstract: A controlled-immersion inspection mechanism gradually immerses a planar pattern of integrated circuits or other articles into a tank filled with water to a given level; across the tank there are two spaced parallel guide tracks along which two carriages, connected by a platform, move from an entry position above the water to an inspection position. In the inspection position the platform supports the articles, in an orderly array, for scanning inspection by a focussed energy beam, preferably an ultrasonic beam. A platform drive drives the platform between its entry and inspection positions. A mesh or other removable cover that permits water to flow but stabilizes article positions may cover the articles during immersion; the mesh is usually removed before scanning.

Abstract: In a scanning acoustic microscope of the reflection type, in which an object is insonified with a series of ultrasonic acoustic pulses in accordance with a preselected scanning pattern and reflected acoustic echo pulses are received and employed to generate an initial electrical signal comprising a sequence of electrical pulses having amplitudes and polarities representative of the magnitudes and phases of the echoes, a directly readable unified interpretative display image is produced from the entire electrical signal; that image includes the usual scanning position and depth information determined by timing of the electrical pulses, together with complete transition information regarding the nature of acoustic impedance changes, based on both the amplitudes and the polarities of those pulses. A compared dual integration method and system, with related gating and display enhancement techniques, comprises the preferred embodiment.

Abstract: A balanced scanning mechanism for driving the transducer of an acoustic microscope or other instrument rapidly back and forth along a linear path comprising the X portion of an X-Y scan pattern comprises first and second carriages guided for movement along an axis X. The transducer is mounted on the first carriage and a counterweight may be mounted on the second carriage; the total mass of each carriage and its contents is equal to that of the other carriage. Drive belts connected to both carriages drive them reciprocally along the X axis with accelerations and velocities that are equal in amplitude but opposite in direction. In some embodiments the two carriages are nested one within the other. In another embodiment the two carriages are mounted closely adjacent to each other on an elongated, rigid guide rail parallel to the X axis, the mass distributions of the two carriages being matched relative to the guide rail.

Abstract: An acoustic microscope or like acoustic imaging system includes an insonifier for insonifying an object with high frequency (over ten megahertz) acoustic waves, a scanner for scanning a high-energy light beam across a reflective interface surface coupled to the object, a photodetector to detect the reflected beam, and a signal processor to convert the photodetector output to an image signal used to produce a visual image representative of acoustic properties of the object; the level of the image signal is detected and is used to adjust the gain of the insonifier to a reference level, the insonification gain adjustment affording a quantitative measure of acoustic properties of the object, usable for comparison purposes, that minimizes or eliminates the effects of system non-linearities and compensates for inadequate dynamic range of system components.