What type of microscope did leeuwenhoek use

Sandwiched between the plates was a small bi-convex lens capable of magnifications ranging from 70x to over x, depending upon the lens quality. Operation of the Leeuwenhoek microscope is simple. The specimen is placed on a pin that is manipulated by the means two of screws, one to adjust the distance between the specimen and lens and the other to adjust the height of the specimen.

The sample translator screw and rod is located at the bottom of the microscope where it passes though a right angled bracket, which secures it to the microscope, and then stops at a metal block located in the middle of the microscope body plates. The specimen-holder pin is connected to the other side of this block, so when the translator screw is turned it moves the specimen up or down.

Another screw, placed into the block perpendicular to the microscope plates, serves as a height-adjustment screw.

When this screw is turned it pushes against the metal plates and moves the specimen toward or away from the lens, acting in a manner similar to a focus knob.

On the back side of the microscope, another screw holds the right angled bracket to the metal body plates and also serves as a pivot point to move the specimen from side to side. Leeuwenhoek spent a considerable amount of time perfecting the manufacture of lenses for his microscopes, and he was able to grind and polish bi-convex lenses to an amazingly high quality. It is also suspected that Leeuwenhoek used blown-glass lenses and that these lenses were the ones responsible for the incredible magnifications of his simple microscopes.

Leeuwenhoek produced these lenses by chipping away the excess glass from the thickened glass droplet that forms on the bottom of a blown-glass bulb. These incredible lenses had a thickness of about one millimeter and a radius of curvature of 0. They had superior magnification and resolution when compared to the other microscopes of the time. The Utrecht museum has one of Leeuwenhoek's microscopes in its collection.

This incredible instrument has a magnification factor of about x even considering a scratch on the lens with a resolution approaching one micron. Microscopy Primer. Light and Color. Microscope Basics. By Andy Coghlan. Leeuwenhoek microscopes contain a single tiny lens the size of a pinhead sandwiched in a hole between two flat rectangular sheets of brass. Objects manoeuvred into place behind the lens can be magnified by up to times their actual size. Leeuwenhoek held the lens close to one eye and squinted through the tiny aperture, with a light source in the background such as a window or candle.

A screw mechanism fastened to one of the brass surfaces brings the object into focus, and even enables it to be rotated. A lens has three properties, it is clear, it is curved, and it bends light. The bending of the light is the key property that allows microscopes to magnify images. Light bends when it enters or exits transparent material at an angle, and the curved form of a lens allows the bending to either "diverge out" or "converge in" depending on the shape of the lens. The bending property is actually due to the speed of light.

We often think of the speed of light as a constant that can never be surpassed, but light actually travels at different velocities depending on the material in which it is passing through. Because of this difference in speed of light between two materials, and given light's peculiarities, when a ray of light, traveling in vacuum or air, encounters a new material, the angle will change so that light "spends less time" in the material.

This level of bending is defined as an "index of refraction. The direct route is actually slower, since running in water reduces the runner's speed. Thus the runner actually takes the "least time route," in which she changes the angles where she enters the water and exits the water to reach the donuts in the fastest time possible.

This "time minimization" serves as an analogy as to why light bends when entering a material. Mathematically, the bending, the index of refraction, is expressed as: and the higher a material's index of refraction, the more the light ray bends. Sahl was interested in the geometry of "burning mirrors and lenses" that can converge light rays from the sun to allow localized increases in temperature and flames.

The law was then independently discovered again by Willebrord Snellius in Leiden in Holland in the early 17th century. Science history recognizes it the equation above as Snell's law, though it was known during the Islamic Golden age by Ibn Sahl and the famous optics theorist Ibn al-Haytham.

With just this simple index of refraction equation, you can calculate how lenses behave. Remember that a lens needs be curved. With this curvature, you can cause light rays to diverge or converge. Let's look at the simplest example, a ball lens. Optics is all geometry, and the equation for calculating focal length based on the geometrical bending only requires we only know the diameter of the sphere d and the index of refraction of the material the sphere is made out of n.

But, you may ask, how does the lens actually enlarge the image and cause the magnification. See the image below, and you will recognize, again, why the curvature of the lens is the fundamental key.

Returning to the parameters of the ball lens:. You see that either lowering d diameter and increasing n index of refraction lowers the effective focal length and increases the magnification. A strange property thus reveals itself. Since diamond has an index of refraction of 2.