Robert and Dag, Yes. Thanks. My question was aimed at getting some experimental results with camera polarizers to decide if I could possibly get elliptically polarised light *without* a 1/4 wave plate using a combination of plane and circular polarizers for cameras. I'm trying to do the job on the cheap.
Going black is not what I expected either, that can't happen with circular or elliptical polarization, as you clearly explain. By the way, I've never found even the best quality plane polarizers (crossed) to exclude *all* the light -- they always let some through due to imperfections in manufacture I guess. I suppose I'll just have to try it out and see what happens. I'll post pictures of the results. Don _______________ Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery Updated: July 31, 2003 ----- Original Message ----- From: "Robert Szasz" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, August 20, 2003 10:40 AM Subject: Re: A test -- 'crossed nicols' > http://panda.unm.edu/courses/finley/P262/CircPolar2/CircPolar2.html > If you can get a quarter wave plate you can create diffrent ammounts of > ellipitality by varying the fast axis of the plate with the polarization > axis on a linear polarizer, 45deg creates circularly polarized light (well > depending on the freq it will vary in ellipicality). > > On Wed, 20 Aug 2003, Dr E D F Williams wrote: > > > Date: Wed, 20 Aug 2003 10:22:50 +0300 > > From: Dr E D F Williams <[EMAIL PROTECTED]> > > Reply-To: [EMAIL PROTECTED] > > To: [EMAIL PROTECTED] > > Subject: Re: A test -- 'crossed nicols' > > Resent-Date: Wed, 20 Aug 2003 03:23:04 -0400 > > Resent-From: [EMAIL PROTECTED] > > > > That's just what I was trying to find out. Special polarizers for > > microscopes cost and awful lot and I want to try a circular polarizer to see > > if it will approximate the behaviour of a very expensive elliptical > > polarizer. Lamda plates also cost at least one arm and leg and I'm thinking > > about what I can do in that case as well. Even a simple 1/4 wave plate, once > > available for the Zeiss range of instruments -- it went into the filter > > holder under the condenser -- was expensive. > > > > Don > > _______________ > > Dr E D F Williams > > http://personal.inet.fi/cool/don.williams > > Author's Web Site and Photo Gallery > > Updated: July 31, 2003 > > > > > > ----- Original Message ----- > > From: "Robert Szasz" <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Sent: Wednesday, August 20, 2003 10:11 AM > > Subject: Re: A test -- 'crossed nicols' > > > > > > > From my knowledge of how a circular polarizer works you will get a 3db > > > loss for every re linerazation (every polarization after the 1/4 wave > > > plate). Two circular polarizers (any positions)therfore would cut the > > > amount of light recieved in half (assuming perfect rejection of the > > > perpendicular polarization). If you place a linear polarizer in front of a > > > circular polarizer it will act just like two linear polarizers, but the > > > light after the 1/4 wave plate in the circular polarizer will be > > > circularly polarized (either right or left handed depending on the way > > > the polarizer was constructed)) > > > > > > On Wed, 20 Aug 2003, Dr E D F Williams wrote: > > > > > > > Date: Wed, 20 Aug 2003 08:34:05 +0300 > > > > From: Dr E D F Williams <[EMAIL PROTECTED]> > > > > Reply-To: [EMAIL PROTECTED] > > > > To: [EMAIL PROTECTED] > > > > Subject: A test -- 'crossed nicols' > > > > Resent-Date: Wed, 20 Aug 2003 01:34:17 -0400 > > > > Resent-From: [EMAIL PROTECTED] > > > > > > > > If anyone has two circular polarizers I'd be grateful if you would > > perform a > > > > test. Put one over the other and rotate to see if the field becomes > > > > completely dark when they are crossed. And ... if you also have an ordin > > ary > > > > polarizer try the same experiment using one normal and one circular > > > > polarizer. > > > > > > > > Don > > > > _______________ > > > > Dr E D F Williams > > > > http://personal.inet.fi/cool/don.williams > > > > Author's Web Site and Photo Gallery > > > > Updated: July 31, 2003 > > > > > > > > > > > > > > > > > > > > > > > > > >
