Microscope Objective Lens Function

All parts of the microscope are important, but the objective lenses - the lower, magnifying lenses - must be treated with particular care. The lenses are of the best quality and need to be handled very carefully. Sometimes two lenses are glued together, and you must be careful not to use solvents such as strong alcohol solutions or acetone, which could dissolve the glue or cement.

Objectives are referred to by their magnifying power, which is marked on the side. The microscope you will use has the following objectives:


• x 10
• x 40
• x 100 (this objective is often called the oil immersion objective; sometimes it has a black or red ring around it for easy identification).

Objectives, showing working distance between front lens and specimen

The mechanical stage

The mechanical stage holds the slide secure and allows the specimen to be moved smoothly backwards, forwards or sideways. Sometimes a scale is fitted to two sides of the stage to show the extent of the movement. This is called the Vernier scale, and it is useful to know how to use it; it can be used to trace a part of the blood film that you need to re-examine or show to your supervisor.

Substage condenser (with iris diaphragm)

The substage condenser is made up of a number of lenses. These centre the light from the mirror, or electric light source, to a central spot on the field. The substage condenser can be raised or lowered to give maximum or minimum illumination.

Inside the condenser is the iris diaphragm. This is used to control the amount of light passing through the condenser. The iris diaphragm consists of a number of interlocking leaves made of a thin metal. It is adjusted by means of a lever.

Filter holder and blue filter

Beneath the iris diaphragm is the filter holder. This is where a blue filter is placed when you use an electric light source for illumination. It has the effect of making the microscope field white rather than yellow.

Microscope Diagram with Name

1. Main tube inclined head
2. Body tube (prism) inclined head
3. Revolving nosepiece
4. Objective
5. Stage (mechanical stage)
6. Substage condenser with iris diaphragm
7. Mirror
8. Base (foot)
9. Ocular (eyepiece)
10. Arm (limb)
11. Coarse adjustment
12. Fine adjustment

MICROSCOPE  INVENTION

Today, we'll explore the invention of the microscope. In biology class, it brought a whole new world into focus. The microscope gave us technology and a better quality of life.

So it's worth examining just how it came to be. Glass was invented about 22-hundred B-C. In the 1st century, Romans discovered if they made the glass thick in the middle and thin on the edges, objects viewed through it looked larger.

People started using lenses more toward the end of the 13th century when eye glasses were made. Magnifying glasses, the earliest of microscopes, came shortly thereafter.

It wasn't until 1590 when the forerunner to the modern microscope was invented. Two Dutch spectacle makers, Zaccharias Janssen and his son Hans found that the proper combination of lenses in a tube, made objects appear greatly enlarged. Their invention was the first compound microscope: which uses two or more lenses and is still in use today.

Galileo, the father of modern physics and astronomy, heard of these early studies. Through his own experiments, he harnessed the power of glass. In doing so, he designed a superior microscope that included a focusing knob.

Then, Anton van Leeuwenhoek, the father of microbiology, developed techniques to grind and polish glass. He made small lenses with great curvatures. With his lenses, his microscopes were able to magnify more than 200 times. He saw things never seen before: bacteria, yeast, blood cells and tiny animals swimming in a water drop.

Microscopes are now are so powerful, it's the equivalent of being able to see a penny on your football stadium seat from outer space. Microscopes continue to be a researcher's enduring partner bringing into focus tiny worlds we endeavor to understand.