Systems and methods for automatic visual inspection of defects in ophthalmic lenses

The method of claim, 6 wherein the at least two points of view correspond each to a first and second different lens orientation with respect to at least one camera axis orientation and optical center position, and further comprising:

• localizing a depth of the defect within a body of the lens;
• and deciding whether the defect is located on the front surface or on the back surface of the lens based on the phase visibility values and modulation visibility values from the at least two points of view and a geometry of a lens orientation to the two points of view;
• wherein localizing the defect on the front or back surface is based on the phase visibility values and the modulation visibility values;
• and
• wherein localizing the defect on the front or back surface is based on one of:
• discriminating that the defect location is on the front or back surface from the defect disparity as seen from the at least two points of view;
• or
• discriminating that the defect location is on the front or back surface from a triangulation of the defect position as seen from the at least two points of view.

An automatic visual inspection (AVI) system for detecting lens defects of semifinished or finished lenses using at least one visual inspection standard, the AVI system comprising:

• at least one camera to measure phase visibility values and modulation visibility values of deflectometric measurements through an inspection area of the lens for two different sensitivities of a deflectometric setup using at least one fringe pattern taken from at least two points of view,
• wherein the sensitivity (S)=Z 2π/p where Z is the distance between a screen and the lens and p is the period of the fringe pattern;
• a detection unit to detect a defect of the lens at a defect location;
• and
• a defect type detector to differentiate whether a defect type of the defect is a prismatic defect type, a transmissive defect type, a lenslet defect type or a cosmetic defect type based on the phase visibility values and modulation visibility values at the defect location as compared to the values of a local neighborhood area.

An ophthalmic lens production line comprising:

• a first automatic visual inspection (AVI) system for detecting lens defects of semifinished lenses using a first visual inspection standard;
• a coating process for coating a frontal surface of the semifinished lenses to create coated blank lenses;
• a second AVI system for detecting lens defects at a frontal surface of the coated blank lenses using a second visual inspection standard;
• a lens surfacing process for surfacing a back surface of the coated blank lenses to create ophthalmic finished lenses;
• a third AVI system for detecting lens defects at a frontal surface or a back surface of the ophthalmic finished lenses using a third visual inspection standard;
• wherein each of the first, second and third AVI system include:
• a lens holder to orient the lenses to provide deflectometric measurements from at least two points of view of the lenses for at least one fringe pattern of dark and bright bars shown on a screen;
• at least one camera to measure phase visibility values and modulation visibility values of the deflectometric measurements through an inspection area of the lenses for two different sensitivities of a deflectometric setup;
• wherein the sensitivity (S)=Z 2π/p where Z is the distance between the screen and the lens and p is the period of the fringe pattern;
• a detection unit to detect a defect of the lenses at a defect location in the inspection area based on the phase visibility values and modulation visibility values at the defect location as compared to the values of a local neighborhood area;
• a defect type unit to differentiate whether a defect type of the defect is a prismatic defect type, a transmissive defect type, a lenslet defect type or a cosmetic defect type based on the phase visibility values and modulation visibility values at the defect location as compared to the values of a local neighborhood area;
• a localizer unit to localize the defect as being located on the frontal surface or on the back surface of the lenses based on the phase visibility values and modulation visibility values from the at least two points of view and a geometry of the lens orientation to the two points of view;
• and
• an invalidating system for invalidating a lens based on whether the defect is a prismatic defect type, a transmissive defect type, a lenslet defect type or a cosmetic defect type, and based on whether the defect is located on the frontal or the back surface of the lenses.