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Leeuwenhoek microscopes. Children's Science Lab

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In the spring of this year, the directorate of the Polytechnic Museum turned to me with a request to help prepare an anniversary exposition dedicated to the 350th anniversary of the birth of Leeuwenhoek.

I readily agreed to the proposal of the museum directorate.

It was decided to prepare a special demonstration stand, which would not only give an opportunity to look into the simple and at the same time surprising in its high qualities Leeuwenhoek's microscope, but also explain how to make such a microscope on your own.

Now all the big work is over, and a cube made of plexiglass awaits visitors, at the corners of which eight active models of the Leeuwenhoek microscope are fixed. Qualified guides are ready to give appropriate explanations and advice on how to make it yourself.

Each of the miniature microscopes is configured for a specific preparation. The magnification of microscopes, despite their simplicity (recall that this is actually a single-lens magnifier), is quite significant: from 50x to 300x! The image quality is such that it can compete with the image quality in a modern ordinary student microscope, made according to all the rules of optical science.

Among the preparations on display are classical Leeuwenhoek's, for example, blood cells and bacteria. Some drugs are quite modern, they are studied at the university by biology or medical students. Among them are plant and animal cells, in which, in some cases, chromosomes are even quite clearly visible.

I would like to take the opportunity to answer numerous questions from readers on the problems they encountered when trying to make a microscope on their own.

I must say that in our previous publications, a microscope of a rather complex design was proposed, difficult to manufacture at home.

In the design, which will be discussed below, the main principle has been changed: not the preparation is attached to the microscope, but the microscope is mounted on a standard glass slide of the preparation. In this regard, the body of the microscope is best made from a thermoplastic plastic plate 1-3 mm thick.

As can be seen from the drawing, the microscope body resembles a trapezoid, at the top of which there is a hole (1) for a microscrew, which is used for focusing. At the base of the trapezoid there are two holes for the support screws (2), and a little higher in the center there is a recess for the locking screw (3). A lens socket (4) is drilled below the microscrew hole. This is a through hole, which should be slightly smaller than the manufactured lens. The dimensions of the microscope body are given based on the standard dimensions of microscope slides (25x75 mm).

The following figure shows the appearance and approximate dimensions of the clamp, designed to fix the microscope in a certain position on the specimen slide using a standard screw (1), which is screwed into the clamp socket (2) and abuts against the recess (3) on the microscope body. The thread of all screws is M3.

Empirically, I came to the following technology, which is the most simple and gives high-quality lenses for a microscope. First of all, it is necessary to take pieces of optical glass, for example, fragments of spectacle glasses or any other old lenses. Fragments should be no larger than a match head. From pieces of glass of large sizes, an ideal ball can only be obtained in zero gravity. Further, an L-shaped bent nichrome wire (0,1-0,3 mm) is heated in the flame of an alcohol lamp or gas burner, and a shapeless piece of glass is attached to its end - the future lens. In order for the glass to turn into a lens, it, together with a wire, is introduced into the flame, as shown in the figure. After melting, the glass drop soon acquires the shape of a ball. Now it must be removed from the flame and cooled. The lens is ready. Using a 50x-10x magnifier, we examine the surface of the ball lens and its internal structures. If the surface is clean and there are no air bubbles inside, the lens can be used for a microscope. It is again slightly heated over the flame and hot is introduced into the hole for the lens of the microscope body. The lens cools down and soldered into the housing. The procedure for soldering the lens must be carried out in such a way that the nichrome wire is on the periphery. Its protruding end is then bitten off with tongs.

The next figure shows how to assemble a microscope on a preparation to be examined.

I want to emphasize that during all the procedures for manufacturing a microscope and working with it, any touching of the lens is unacceptable. All manipulations are carried out by holding the nichrome wire with tweezers.

By loosening the locking screw, the microscope can be moved along the length of the specimen. When the locking screw is tightened, the microscope can only be moved along the slide left and right. Lighting requirements for this microscope are quite simple - an ordinary table lamp. The optimal distance from the light source to the microscope is selected empirically.

Microscope housing: 1 - microscrew hole; 2 - holes for support screws; 3 - deepening of the locking screw; 4 - lens socket

Lens manufacturing scheme: 1 - L-shaped nichrome wire with a piece of glass; 2 - a shapeless piece of glass in a flame takes the form of a ball with a perfectly polished surface

Microscope clamp: 1 - locking screw; 2 - threaded clamp socket

Assembled microscope in section (the designations are the same as in the first figure)

General view of the microscope

Author: A.Mosolov

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