Re: Projector from Hell

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

Oliver wrote:
> you don't have a projector
> from Hell, you have a slide with a film base from Hell!  I had some
> experience exploring this many years ago, and discovered that a few
> batches of film have a base material that unevenly rotates the axis of
> polarization of polarized light passing through it. 

Fascinating.  Back in the old days, before computers were commonly 
used to describe stress fields, we would cut a piece of plastic to
the shape of the part and stress the part proportionately, and  
read the stress with crossed polarizers.  Have I told this story 
before?  Sounds to me like your film base has residual stresses (not 
properly stess-relieved 8-).  Maybe Dr.T can tell us how to relieve 
stress.  Also, maybe Allan Woods could prescribe something for us.  
What do you say, Dr. T?  700C for 2 hours?  Inert atmosphere?  I 
wouldn't expect a warpage problem under these conditions.  8-)  8-) 

John B


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