Hi Ted, I have been looking at your aurora pictures with jealousy, but I notice you were having problems with a new camera. I would recommend turning off the autofocus and focusing manually so the camera doesn't hunt during dark phases. Also, for star trails, turn the exposure dial to manual, stop the lens down and open the shutter for an hour or so, one thing to watch is the battery drain, holding the shutter open uses a lot of battery power and if you can get a separate battery pack it will be a good insurance. Keep getting those great snaps.
Quartz wedges, real ones, can be found on fleabay from time to time and sometimes you can buy them for pretty reasonable prices. They are an accessory of petrological microscopes. If you pay less than $75.00 you are getting a very good deal. Sometimes they need to be recemented but this is not a moonshot though it may be more than many people want to do. The cementations have to be pretty bad before you have to do it. You can cement them with canadian balsam or with Norlands optical cement or with windshield hole repair (the blue light curing type). You get the old cement out and apart with methylene chloride paint remover and make sure you put it back together the same way it came apart. (after you clean the three pieces carefully).
There are two pretty good alternatives.
One is to buy Dr. Hannemanns quartz wedge simulator which uses molded styene with residual stress to simulate the quartz wedge. I believe he collaborated with someone called Daly so the wedge is called a Hannemann Daly quartz wedge simulator. He sells them fairly cheaply.
You can also make a similar item by using stepped layers of transparent cellophane tape. This method was elaborated in Elizabeth Bell's classic Crystals and Light books and the little lab manual that goes with it. You can get the book from Dover publications.
What is the quartz wedge used for in a gemological context? I'm familiar with their use to bump up interference colors in petrology, though I have pretty much never used it.
You can search the posts of the late list member "Doos" to find expositions on that subject. You can use them to aid in determination of optical character and sign just like in the petrological microscope. Under conoscopic observation.
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