Markings on a polarized progressive

[donovanbaldwin]

As I have mentioned before, I used to work in an optical lab, but have been out of the business for 11 years. I have been working for the last four months in an in-house lab, relearning my trade.

The other day, I surfaced a pair of polarized progressive lenses. I am still not familiar with all the markings, so just assumed that everything I saw was supposed to be there.

However, when the finished glasses went for final inspection, they were rejected because of four marks, two on each lens.

The marks appeared to me to be produced on the surface of the lens just like all the other markings. They seemed to be specifically placed, were symetrically placed on the lens and all had the exact same appearance. The person inspecting the lenses said that they looked like some sort of clamp marks, and that he would have to reject the lenses.

The markings were four straight lines, each approximately 3mm long, each one a few mm directly below the four fitting circles.

Are these actually defects, or are they supposed to be there?

Thanks.

Don

[gemstone]

Originally Posted by donovanbaldwin

As I have mentioned before, I used to work in an optical lab, but have been out of the business for 11 years. I have been working for the last four months in an in-house lab, relearning my trade.

The other day, I surfaced a pair of polarized progressive lenses. I am still not familiar with all the markings, so just assumed that everything I saw was supposed to be there.

However, when the finished glasses went for final inspection, they were rejected because of four marks, two on each lens.

The marks appeared to me to be produced on the surface of the lens just like all the other markings. They seemed to be specifically placed, were symetrically placed on the lens and all had the exact same appearance. The person inspecting the lenses said that they looked like some sort of clamp marks, and that he would have to reject the lenses.

The markings were four straight lines, each approximately 3mm long, each one a few mm directly below the four fitting circles.

Are these actually defects, or are they supposed to be there?

Thanks.

Don

The marks could be caused due to heat around manufacturers markings during blocking. You may be able to remove them using heat. They could also be permanent marks to align the lens for finishing or verification. Be mindful that lots of lenses have various marks 4 below the fitting cross. What lens type and brand do you have? A good start would be to examine a unsurfaced lens to see what markings coincide with what your inspector is finding. Also check the verification patterns supplied by the manufacturer. Sounds likely to me you are about to throw away a good pair of lenses.
Also most polorazed lenses have markings on the lens edges to align the polarizing axis. Those are near the edge of the lenses and usually are cut off during edging.

[Jacqui]

I agree with Gemstone Recheck the lenses.

[donovanbaldwin]

Thanks! I agree that they seem to be alignment markings and are of the same quality as other markings on the lens and are not in the vision area and should not interfere any more than the other markings on the lenses.

Don

[Striderswife]

I've seen these markings in single vision polarized lenses, too. So I'm also gonna agree with Gemstone, that they are there for alignment of the polarization. Even if the lens is spherical, you want the polarized filter going the same direction in each lens.