Catching up while locked down
I have become used to not having enough time to do everything that I want, even though I retired from work several years ago. I enjoy going to as many microscope meetings as I can in and around London, and further afield when I can get a lift, but preparing demonstrations and writing reports on the meetings for the website takes a surprising amount of time. From the end of March, with no meetings to go to, I suddenly had time for microscopy.
Olympus microscope documentation
The first thing I did was clear the backlog of Olympus microscope instruction manuals, brochures, repair manuals and exploded parts diagrams that I wanted to scan and convert to PDFs so that they can go on my Olympus microscope documentation web page. Some of them came from Brian Bracegirdle’s estate, some were donated by other people, and others came from Club meetings. I try to produce good PDFs, so I use black card behind pages when I scan them to stop text on the other side of the page showing through, and then adjust levels so that text is black and paper is white; it is not a quick process. I also add metadata (title, subject and keywords) so that they are easier to find with search engines, and OCR them so that the text can be searched.
Scanning Olympus documents
Scanned Olympus documents
Making the Quekett website secure
The second job I tackled was updating the Quekett website to use HTTPS (Hypertext Transfer Protocol Secure) so that any passwords that members enter and any messages that people send are transmitted securely. Our website uses a cache and a content delivery network to make pages load faster for users anywhere in the world, so it is quite complex. My first attempt at updating failed, with lots of images missing, and I locked myself out of the admin console. I had to use the backups to revert to the previous day’s version of the website so that I could log in and try again. More time on Google allowed me to identify the problem and find a solution (we needed 2 SSL certificates, one on the web server and another on the content delivery network), and my second attempt succeeded. Now we should do better in Google searches, and pages should load a bit faster.
Closed padlock icon in Google Chrome browser
In October 2016 I acquired some Olympus infinity-corrected metallurgical objectives and a brightfield vertical illuminator, and in October 2018 I acquired a TH transformer that provides the proper voltage and current, but the plugs and sockets were incompatible. I intended to try to access the output wires inside the casing, but before I could do this I acquired a second TH transformer that had already been modified with 4 mm sockets.
Olympus TH transformers (left one modified to accept 4 mm plugs)
My collection of Olympus documents includes an exploded parts diagram of the lamphouse cable, but I could not work out how to get access to the wires at either end of the cable, so I still could not use the equipment. With more time, I decided to cut the cable and fit an extension with suitable plugs.
Cable from BH2-MLSH lamphouse with 4 mm bunch pin plugs (original plug on right)
Now I have plenty of light to use the objectives and I can start looking for interesting materials to examine.
Olympus BHT with BH2-MA vertical illuminator and MSPlan objectives
Calibrating an eyepiece reticle
Another job that I have never quite got around to is calibrating an eyepiece reticle for my SPlan and MSPlan objectives (the ones that I normally use for photomicrographs) using my stage micrometers. I have an Olympus Micro WHK 10x/20 L eyepiece with a built-in 10 mm reticle that is divided into 100 parts of 0.1 mm; the top section can be rotated to focus on the reticle. The reticle is cracked, but the markings are not affected.
Reticle in Olympus Micro WHK 10× eyepiece (photographed on a light box, with the top section of the eyepiece removed, Canon EOS 600D with 60 mm f/2.8 EF-S macro lens)
I also have an assortment of old and recent 3″ × 1″ stage micrometers, including one for reflected light. I find the old ones with engraved markings made by Graticules Limited much easier to use than the modern Chinese ones with printed markings.
Stage micrometers (top for transmitted light with a scale on clear glass, bottom for reflected light with a scale on a mirror)
To calibrate, focus on the stage micrometer, adjust the lighting for Köhler illumination, and use the focusing helix on the eyepiece to get the reticle in focus. Use the mechanical stage to line up the zero points of the stage micrometer and the eyepiece reticle. Find a point where the 2 scales line up nicely; in the photo below, 60 reticle divisions equal 3 micrometer divisions, which we know are 0.1 mm apart. Then a bit of arithmetic:
(3 × 0.1 ) ÷ 60 = 0.005 mm
tells us that 1 eyepiece reticle division equals 0.005 mm for this objective.
Calibrating a 20× objective (thick lines are 0.1 mm apart on the stage micrometer, thin lines are the eyepiece reticle) (afocal setup, Canon EOS 5D Mark II with 50 mm f/1.8 EF standard lens supported on a copy stand above Micro WHK eyepiece in the vertical tube of a trinocular head)
I worked out the real sizes for 1, 10 and 100 reticle divisions for the objectives that I use most often:
Eyepiece reticle calibrations
Preparing for gossips
Gossip meetings usually give me an incentive to do some microscopy, and for the July “Hairs and fibres” gossip (our first Zoom meeting), I tried to photograph the scales on the cuticle of a human grey scalp hair. I don’t make permanent slides, so to hold the hairs straight I stretched them across an aluminium cell slide and fastened them with Mineral Tack.
Holding hairs straight
I took some photographs with normal light and with crossed polarisers (the cortex of human hair is birefringent) and showed them during the gossip.
Scales on the cuticle of human grey scalp hair (hair diameter 0.092 mm, with crossed polarisers in the lower photo, 20× objective, 2.5× photo eyepiece, Canon EOS 5D Mark II, EOS Utility)
Using polarisers gave me an idea for a presentation on getting started with polarised light microscopy for the next Zoom gossip, the joint meeting with the Bournemouth Natural Science Society. I showed how to use a photographic polarising filter as the polariser, a disk of polarising film as the analyser, and all sorts of plastic film as a retarder. I have been accumulating pieces of plastic film to test as retarders, and I devised an annular mount to make it easy to hold and rotate them; it was easy to make with a compass cutter.
Making annular mounts with a compass cutter
In addition to the PowerPoint, I showed a live view through my microscope of adjusting the polariser for extinction, rotating the slide for the best image, and using a retarder to change the background and specimen colours.
Thin section of sillimanite (crossed polarisers plus retarder, 4× objective, 2.5× photo eyepiece, Canon EOS 5D Mark II, EOS Utility)
For the August gossip on Ernie Ives’ slides, I showed photos and photomicrographs of two of his wood section slides and two of his insect slides.
Ernie used a consistent layout for the 3 wood sections on his slides; the large section on the left is transverse, top right is radial and bottom right is tangential.
Wood section slides by Ernie Ives
Tangential section of wood of teak (Tectona grandis), stained with safranin (10× objective, 2.5× photo eyepiece, Canon EOS 5D Mark II, EOS Utility)
Tangential section of wood of southern magnolia (Magnolia grandiflora), stained with safranin (10× objective, 2.5× photo eyepiece, Canon EOS 5D Mark II, EOS Utility)
When I examined and photographed the insect slides for the gossip I was surprised that they were not up to Ernie’s usual high standard; one has lots of air bubbles, and the other has a broken specimen and very obvious supports for the coverslip that protect the specimen from being squashed..
Slides of ichneumonids by Ernie Ives (Canon EOS 600D with 60 mm f/2.8 EF-S macro lens)
Discussion at the gossip provided an answer: the slides appear to be Ernie’s early experiments with the Ralmount mountant.
Ichneumonid on a slide by Ernie Ives (body length 2.1 mm, 2× objective, 2.5× photo eyepiece, Canon EOS 5D Mark II, EOS Utility)
Spacers supporting the coverslip, seen through the slide (Canon EOS 600D with 60 mm f/2.8 EF-S macro lens)
Preparing for the virtual Annual Exhibition of Microscopy
When it became clear that it would not be possible to hold Quekex in the Natural History Museum, the committee decided to hold a virtual event spread over 6 days. Trying to hold everything on one day would have involved members staring at their computers for several hours, not good for their health or domestic harmony.
I normally take photographs and make notes at Quekex so that I can prepare a meeting report for the website, but with a virtual event I must have everything prepared in advance. So I am back to working on the website instead of using a microscope. I have had to convert all of the exhibits into web pages, prepare image galleries of all of the photomicrographs and slides submitted for Barnard Awards, and prepare pages to display the artwork and videomicrographs, all in time for the opening of the Exhibition.