Manufacturing

Laser Ultrasonic Camera

Related Patents:  5827971 ; 6134006 ; 6486962 ; 6401540

Contact: David R. Anderson

Phone: (208) 526-0837

E-mail:  Send E-mail

The INL Laser Ultrasonic Camera directly images (without the need for scanning) the surface distribution of subnanometer ultrasonic motion at frequencies from Hz to GHz. The INL Laser Ultrasonic Camera employs a photorefractive (adaptive) approach to interferometry to provide full-field real-time images of ultrasonic motion over large areas. The basic information to be measured, the ultrasonic motion of the surface, is impressed onto the phase of the detection laser beam just as with the other passive methods. The entire optical image of the vibrating surface is formed inside the photorefractive material where it undergoes real-time processing due to the dynamics of the photorefractive process. Nonlinear optical mechanisms within the photorefractive recording material are utilized to produce an output image that is a "picture" of the vibrating surface. The net effect is that interferometric detection is accomplished over the entire vibrating surface all at once without scanning, producing an output that can be viewed directly with the eye or with a television camera. No additional electronic or computational processing is required. By eliminating the need for scanning over large areas or complex parts, the inspection process is greatly speeded up. Laser ultrasonic methods provide noncontacting approaches that are desired for field applications, such as for remote measurements and in-situ manufacturing process monitoring. An example concerns the anisotropic properties of sheet materials that can be determined by measuring the propagation of elastic waves, known as Lamb waves, in different directions. The INL Laser Ultrasonic Camera produces a real-time image of propagating Lamb wave modes in all directions along the sheet simultaneously. The resultant image provides a direct quantitative determination of the phase velocity (which depends on the material microstructure, density and elastic properties) in all directions immediately, showing plate anisotropy in the plane. Ultrasonic motion of all types in most materials can be imaged and measured with this new approach.