| 摘要 |
<p>The invention relates to a method for determining local physical properties of an object (8), said properties causing transitions in the phase velocity in said object and in connection therewith the local acoustical impedance of said object, e.g. the contours and the type of eventual inhomogeneities, surface roughnesses, or layer thicknesses in a multi-layered object, and also relates to an apparatus for assessing such properties, said apparatus comprising a support (3) for said object, a signal generator (6), and an electro-acoustical transducer (5) for transforming the output signal of said signal generator into sound, said transducer being adapted to transmit sound waves towards the object to be tested through a medium (2). Generally the invention has as its purpose to increase the resolution of the assessing method and in view thereof proposes to carry out the mentioned method in such a way that use is made of stationary sound waves, in such a way that an interference pattern (13) of densifications and rarefications representative of the physical properties involved can be formed in a medium by cooperation between the incident and the reflected sound waves, that on said interference pattern electromagnetic waves are directed and the deflection pattern of the electromagnetic waves deflected by said interference pattern is assessed. In view thereof an apparatus comprises a source (10) of electromagnetic waves, a transducer (14) for transforming said electromagnetic waves in a signal representative of the intensity of said waves and display means (15) for displaying on basis of said signal the intensity of the received electromagnetic waves, said source transmitting electromagnetic waves towards the transducer through the sound waves transmitted towards the object to be tested and eventually reflected by said object.</p> |
