Automatic calibration system for ultrasonic inspection
US4462082A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1981 |
| Grant date | Jul 24, 1984 |
| Priority date | — |
| Expiry date | Sep 17, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N29/4463
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus is disclosed for calibrating an ultrasonic inspection system having a plurality of transducers (12a, 12b, 12c) coupled by a common amplifier (16) to a distance-amplitude correction (D-AC) circuit comprised of a multiplying digital-to-analog converter (26') which receives, as a function of the transit time of an ultrasonic signal measured by a clock counter (34), a D-AC correction stored in a look-up table in a random access memory (24'). The D-AC correction function stored in the look-up table for each transducer is the inverse of a return signal response curve determined by measuring the peak amplitude of return signals from calibration holes at known depths in a test block (10) while in a calibrate mode, i.e., with a switch (SW) in a state to bypass the MDAC. An equation of a curve that best fits the peak measurements is then found by a digital computer (20) and used to determine the values of points along a curve superimposed on the response curve, except at near field where the calibration system is provided with truncation for near-field effects. Inverse values of these points are then stored in the look-up table for use as correction factors applied to …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.