Siliceous and Delicious

Been working on calibrating the microscope so that I can actually determine how good (or bad) the resolution is of the objectives that are available and seem to work with the ODP slides. Andy was finally back today, so I was able to get at his stage micrometer and begin that laborious process. Set the pixel scale for the 4x Olympus objective, then jumped right up to the 40x Olympus SPlan, which I found in a drawer in the microscope room, which has a numerical aperture of 0.70 and thus should theoretically perform better than the 40x Olympus DPlan PO that Andy gave me—not sure if 0.05 makes a big difference in numerical aperture, but I do know that bigger is better. The aperture on the 63x oil immersion objective I had been hoping to use (just for sake of comparison) is a whopping 1.40. Never going to get anything near that good working considering the lenses on offer here, and the irritating way these samples seem to be prepared. Ah well.

Once I had calibrated that 40x objective, I figured I’d measure some shell thicknesses and see how thin the shells could get before I lost resolution. I measured a shell thickness of 2.8 µm without much trouble. Nice, but at the very thick end of what I expect to see for shell thicknesses—the slide was also one from the Oligocene, Pleistocene shells will be much thinner (depending on species, of course). Anyway, I thought I’d try a Pleistocene slide to see what I could see, when the next level of total disaster struck—this slide was so thick I wasn’t even able to use the 40x objective. Fuck. Fuck a ducky duck. Even though this objective has a larger working distance, it’s not enough to image through the bottom of the slide (i.e. the main slide glass)—so, this fucking sucks.