Polarized lenses continued

[Kurt Brandon]

Regarding marking/blocking polarized lenses,
my present conception is as follows:

1. On a spherical lens, you may safely rotate the lens so that the lensometer dot line coincides with a line connecting the two edge marks on the polarized lens.

2. On a lens with cylinder correction, the alignment of the cylinder axis is done in the usual way. If, when the lens is oriented properly for spotting, the polarization-axis line is not coincident with the spot-line, the lens was manufactured wrongly and is unusable.

Is this correct?

What is the difference between the "180 line" and the axis of polarization?

Kurt

[Jeff Trail]

Kurt!!!!

You got it!!.. on both counts...1#,2#

The last question about a "180" line .. in optic's you'll see this phrase pop up a lot in conversation about polarized as well as when talking about PAL's .. it's a generic phrase that we all use to talk about a line running across the lens on a parallel .. 0-180 got a circle run a line straight across and that's 0-180 meridian horizontal.. on the vertical its the 90 degree meridian ..it's just been shorten a little and most people just say the "180" ..
Well, now that you got that problem solved.. you'll not have to worry about it any further.. isn't it amazing how something seems confusing and then it just "clicks" and it makes perfect sense ? :)

Jeff "grind'em if ya got'em" Trail