Laser Speckle Inferometry
First Time Around
Second Time Around
Laser
Microscope lense: disperses The laser light on the wall
Camera
Computer collects data from camera and turns it into a pattern
Wall with wall painting
When the laser light bounces off the wall and interpheres with another laser light it cancels out so no laser light will be seen on the camera in that area
Same apparatus except speaker
Now with the addition of sound, areas of paint which have seperated from the wall will reverberate. When the lasers hit the wall they will bounce off differently as the wall is moving,.The surface of the wall will change as the paint seperated from the wall moves back and forth causing lasers waves to interphere differently. The pattern will be different from the first time around. Areas where the pattern is different from the first time around are areas which have separation.
Speaker
Click on Infographic to learn even more!!!
A man using an XRF machine in 1958, it was one of the earliest of such machines. courtesy of the U.S. Geological Survey