Sulphur under cross polarised light
Image and text by Ron Neumeyer, Canada

Image of the month

The specimen slide was prepared by placing a very small amount of powdered sulphur (half a dozen grains) on a slide. A coverslip was placed on top of the powder and the slide warmed over a candle. The trick is to apply enough heat to melt the sulphur (turns to a clear liquid) without cracking the slide. I broke a few slides before achieving a successful melt. Once the sulphur melts the slide is allowed to cool before being examined. I found that each melt was different, and several failed to show any interesting effects under crossed-polars. (It is a very frustrating process! If anyone knows a better way to do this I would love to hear about it!)

 The picture was taken using a flash, planapo 10x objective and Ektachrome 50 slide film. (As you may know an apo tends to give a visual image with grey-black, rather than jet black background because of internal birefringence). Therefore, the "literature" wisely recommends achromat objectives for polarized light microscopy. However, I have found that Ektachrome, and other colour film, records the background as jet black anyway, apparently because film is not as capable as the eye in separating slight differences in contrast. Needless to say the apo yields images with better definition and more intense colour then an achromat. For this reason I recommend them for "artistic" polarized light photomicrography, where impact, rather then accurate colour renditions, is the goal.

 Editor's Note: The wonderful effects created when observing crystals under cross polarised light is relatively easy for the amateur to achieve. Two articles for the novice - Technicolour Nature , explain the technique and can be found in the Micscape Article Library.

 The Micscape and Microscopy UK Editors thank Ron Neumeyer for submitting this month's Image of the Month.

Comments to the author Ron Neumeyer welcomed.

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