Apparatus and method for measurement of a liquid droplet

An apparatus for measuring the characteristics of a droplet of ink comprising:

• a laser for generating and projecting a beam of light along a path;
• a photodetector along the path of the beam for receiving the beam and providing an electrical output corresponding to the amount of the beam received;
• lenses along the beam path between the laser and the photodetector for forming the beam in the form of a thin sheet at a focal point along the path beyond the lenses;
• and
• an ink jet head adjacent the beam path at the focal point for projecting droplets of ink toward and through the thin sheet of the beam.

A method of measuring the characteristics of a droplet of a liquid comprising the steps of:

• projecting a beam of light along a path;
• focusing the beam at a focal point using a len;
• forming the portion of the beam at the focal point into the shape of a sheet beyond the len;
• detecting the beam after the beam passes the focal point and providing an electrical signal corresponding to the amount of light detected;
• and
• passing a liquid droplet through the sheet portion of the beam to varying the amount of light detected by the detecting step.