Siliceous and Delicious

Wow, that one came by fast. We’ve broken the 400-day barrier, and time is ticking away faster. I think this might actually be true—I’m pretty sure the seconds on my screentop countdown clock have literally become shorter as they tauntingly and unhaltingly dwindle away into an ever-growing, unseen ocean of urgency.

After getting the progress report text out of the way yesterday, decided I would be quicker today in getting back to the microscope. Just one task to do before then: go see Jacques and get his signature. This was successful in accomplishing the aim of getting his signature, but also a good chance to vent some frustration and worry about graduating. He, too, was concerned—and previewed what was (unsurprising to me) certain to come up at the meeting, namely his deep suspicion about aiming to graduate within 12 months when there are no results at all to present at the moment.

This was followed by a brief and very high high, when I explained my current imaging problem and Jacques procured and loaned me a long working distance 60x objective along with various adapters. I brought these back and at first found that the objective indeed produced an image, leading me to celebrate in the belief that I had solved my objective problem. When I then tried to calibrate the objective for magnification using the stage micrometer, I found that I wasn’t able to get very good focus. Some googling explained why this was likely to be the case—the lens is infinity-corrected, i.e. it sends collimated, i.e. parallel rays up the main tube, which (in a modern microscope) are focused by a tube lens to converge at the back of the eyepiece to form a clear image. Older lenses, for which our microscope is built, are designed such that the rays passing up the tube are not collimated but converge to focus at the back of the eyepiece without any further lenses in the tube.