Machine vision applications today are diverse and often innovative, as demonstrated by ATM Automation’s latest use of the technology within a system that manufactures precision optical lenses. This recent configuration of the machine vision systems within this cell demonstrates the capabilities of the technology to both vision inspect and optically inspect a range of disposable tonometer optical lenses.
Tonometry is the procedure used by eye care professionals to check the intraocular pressure inside the eye. For these precision molded parts to function correctly, it is essential that the optical surfaces are flat to within a few microns. ATM's production solution uses two separate vision systems, one to vision inspect each component for contamination and correct laser de-gating before measuring the flatness of each individual molded lens surface using the second system in conjunction with structured lighting.
(Photo, below) ATM’s system uses machine vision to perform quality checks and measure optical flatness on precision tonometer lenses.
The first machine vision system checks for contamination and gate witness on each individual lens. Indexed into the inspection station using a rotary table system, the lenses are backlit to allow inspection checks to take place. Any contamination detected which is greater than 0.3mm2 and/or having gate witness of 1.0mm results in that lens rejection from the system. Lenses that pass these inspection checks are then presented to the second vision system, which is used to check optical flatness.
This part of the system uses a clever lighting arrangement, combined with a PC based machine vision system, to measure the flatness of the optical surface to micron level to determine whether the component is within the required, fine tolerance specification.
The vision inspection stations are just part of a full turnkey system that performs all operations from de-molding with a 6-axis robot and part handling and transfer using dual rotary tables and several pick and place mechanisms. A laser de-gating system was also incorporated to allow a non-contact method of gate removal, eliminating any potential for mechanical shock that could damage the lens. A further benefit was the super smooth finish achieved by the laser.
Source: ATM Automation Limited