I have always been fascinated by optical instruments that provide magnified views of Nature: microscopes, binoculars, telescopes. As a child I badly wanted to watch the Moon, planets, and stars, and see as much detail as I could on all possible targets; at the same time, I avidly used a toy microscope to watch the microworld. So it is not a surprise to find out I have grown up into a particle physicist - I worked hard to put myself in a vantage position from where I can study the smallest building blocks of matter with the most powerful microscope ever constructed, the Large Hadron Collider (LHC). 

Yet, as cool as the LHC is, I have to say that the use of an optical microscope offers more satisfaction, as your eye pupil is directly in the line of sight. Microscopes are not a typical tool in a particle physics lab, unless you are a builder of silicon detectors. But the price of decent microscopes has steadily decreased in the past decades, such that nowadays a few hundred bucks can get you equipped with a satisfactory instrument.

I waited for a long time to purchase a microscope, reasoning that I might end up not using it enough; but last month I finally did it. What tipped the balance was mainly the fact that soon my daughter Ilaria will start to use it for her studies in Medicine, and it is cool to get started together using the instrument and setting up a small microbiology lab at home. The thing I bought (a T490B microscope, see pic below) is produced by AmScope in the UK, and at a price tag of little more than 300 euro it offers all the basic functionalities of much more costly, professional instruments. Mechanical movements are smooth and precise, allowing to easily move around the field of view even at the highest magnifications.

The optics of the instruments are also reasonably good; lenses are not apochromatic, but that bit is much more important in a telescope. There are four objectives and two sets of eyepieces, providing binocular views at 40x, 80x, 100x, 200x, 400x, 800x, 1000x, and 2000x. The last two magnifications are possible through the technique of oil immersion - something I just learned to do. Basically you rely on the higher refractive index of oil, to provide a higher power without large diffraction. I was concerned that the lens could get irreparably dirty with such a procedure, but I found out this is not an issue.

2000x magnification is a lot, indeed - but are the views still sharp? You get to fight against reduced illumination (getting enough photons through the specimen and into the minuscule lens is a challenge, as enough wattage of the lamp would require cooling), as well as against the fact that the objects you image have sizes not too different from the very wavelength of the light you bounce off them. At 2000x, an apparent size of one millimeter corresponds to objects half a micron wide, which is the wavelength of green light. That means diffraction is an issue. The high refractive index of oil (1.5 is typical) reduces the effect, buying you a bit more resolution power.

So what do I plan to do with this instrument? Of course, I want to learn all that there is to learn, and then some more! For one thing, I want to use it for "simple" laboratory tests. A list of what I have in mind, and have started to get ready to do, is:

- checks of blood composition (characterization of white cells, piastrine counts)
- tests of seminal liquid (sperm count, characterization of anomalous forms, motility measurements, eosin test, DNA tests)
- Pap test of epitelial tissue (it is not very hard to do, although it requires a five-stain colouring procedure) to check for adenocarcinoma precursors

Of course there much more one can do with a good microscope, but there is a learning curve, and some equipment to procure. One thing I already have is a precise (1mg smallest division) scale, which allows e.g. to have a decent idea of the amount of liquid one puts under a cover slide. I also purchased some stains (eosin and hematoxilin), and am struggling to find good providers for the others I need. But there are more things to get, and it is going to take a while.

One cool thing is that the microscope allows to take footage with a PC, parfocal with the binocular eyepiece. I haven't purchased a PC adapter yet; I am actually not very interested to acquire images with it, and am happy with the cellphone shots one can take through the eyepiece. For instance, below is a pic of a sperm sample, coloured with eosin:

And below are two high-power (2000x) pictures of blood - funnily, the hematoxilin stains white cells in red, and red cells remain whiteish.

So, all in all I am very happy of this new instrument and am having lots of fun with it. And slowly I am working my way to obtain quantitative information with it. Who knows, maybe one day I'll detect early on some pre-carcinous cells in epitelial tissue and save my own life!