Device for contact-free thickness or interval measurement

A device for contact-free thickness or interval measurement, comprising:

• light source means for generating a sharply concentrated light ray beam in a prescribed direction;
• a beam deflector means for periodic deflection of the light ray beam at right angles to the prescribed direction;
• a beam divider positioned after the beam deflector;
• a first and second light-sensitive detector at a region of a light ray beam divided out from the prescribed direction by the beam divider, the first and second detectors having an optical axis receiving light from a specific direction;
• at least one third light-sensitive detector whose optical axis intersects the light ray beam at a reference plane;
• electronic evaluation means for generating from signals of the first and second detectors a control voltage corresponding to a deflection time of the light ray beam between the first and second detectors and also generating from signals of the first and third detectors at least one voltage impulse which is a measure of an interval of a surface of a measured object from the reference plane;
• an impulse/digital converter to which the voltage impulse is supplied;
• means for creating a reference voltage;
• means for generating a corrected reference voltage by changing the reference voltage in a direction opposite to a deviation of the control voltage from a normal operating voltage;
• and
• a digital/analog converter means for creating an analog output based upon the corrected reference voltage and digital output from the impulse/digital converter.