Apparatus and method for detecting moisture in a printing plate exposer

A method for detecting a quantity of moisture on a measuring spot in an exposer for printing forms, which comprises the steps of:

• providing an apparatus having an evaluation device, a radiation source and a photoelectric converter for detecting radiation reflected or scattered by the measuring spot;
• emitting radiation from the radiation source having a wavelength lying within an absorption wavelength range of the quantity of moisture on the measuring spot by emitting at least one measuring beam having a first intensity from the radiation source;
• generating a measured signal at the photoelectric converter;
• evaporating the moisture on a surface of the measuring spot;
• generating an electric reference signal as a result of reflection of the measuring beam having the first intensity at the surface of a dry measuring spot following the evaporating step for evaporating the moisture;
• and
• comparing, in the evaluation device, the measured signal from the radiation reflected from the measuring spot with the electric reference signal from the radiation reflected from the dry measuring spot.

A method for detecting a quantity of moisture on a measuring spot in an exposer for printing forms, which comprises the steps of:

• providing an apparatus having an evaluation device, a radiation source, and a photoelectric converter for detecting radiation reflected or scattered by the measuring spot;
• emitting radiation from the radiation source having a wavelength lying within an absorption wavelength range of the quantity of moisture on the measuring spot by emitting at least one power pulse having a given intensity from the radiation source;
• monitoring the radiation reflected with the photoelectric converter resulting in reference signals;
• evaluating the reference signals to determine when no changes occur between successive reference signals;
• and
• determining an amount of energy of the power pulse needed in order that no change occurs in the successive reference signals.