Method for measuring thickness of transparent objects

摘要

A method is provided for measuring the wall thickness (T) of transparent articles (5) using non-collimated and diverging light (1,2) in the form of a small point source or elongated narrow line of light, measuring the spacial separation of the reflections (3,4) from the nearest and furthest surface by means of a two-dimensional image sensor (9) and a computational device to calculate the geometrical corrections needed to provide accurate thickness measurements. In situations where smooth thickness variations occur, a symmetrical two view embodiment using two non-collimated and diverging light sources and two image sensors at equal but opposite angles of incidence from the same side of the object provides a means to correct for errors caused by internal prism effects as a result of undulations of either the nearest or furthest surface.