Vibrating microscope
A vibration microscope is a measuring device invented by Hermann von Helmholtz in Heidelberg in 1860 , with which one can examine the vibrations of stringed instruments .
The microscope consists of a tuning fork , which is set in vibration by an electromagnet , and a magnifying unit. A colored marking is applied to the string to be examined . If the string now vibrates perpendicular to the tuning fork, the color point moves on a Lissajous figure due to the superposition of string vibration and tuning fork vibration . Since the oscillation of the tuning fork is known, the oscillation of the string to be examined can be determined from the Lissajous figure.