The three basic, structural components of a compound microscope are the head, base and arm. Head/Body houses the optical parts in the upper part of the microscope. Base of the microscope supports the microscope and houses the illuminator. Arm connects to the base and supports the microscope head. For each microscope and imaging device ZEISS is offering numerous additional microscope components and product upgrades. Select from a broad range of microscope parts like objectives, filters and light sources with different illumination techniques.
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Many important anatomical features, especially those that function at the tissue or cellular levels, are too small to be seen by the unaided eye. The compound microscope is a valuable tool for magnifying small sections of biological material so that otherwise inaccessible details can be resolved.
There are many different types of microscopes. We shall only learn about the compound light microscope. It uses visible light to visualize the specimen, but passes that light through two separate lens to magnify the image. The compound microscopes we will use in this course are sturdy instruments but they still have a lot of moving parts. They can be damaged and broken through misuse and mishandling. A large part of learning how to use the microscopes properly involves learning how to avoid damaging it. To do that, you first have to know which parts are which. Figure 4.1 identifies the key parts of the microscope that you need to be familiar with.
In Figure 4.1, there are two compound microscopes shown. The one on the left is monocular and the one on the left is binocular. Many of the parts of the two microscopes are in slightly different locations. Get used to this. Different brands and different models of microscopes position the key parts differently.
When you first sit in front of a microscope, you should always take a second to find the key parts, especially the focus knobs, the condenser adjustment knob (if present), and the stage control knobs. When viewing a specimen, your eyes will be at the eyepieces, and if you grab the wrong knob by accident, you can lose your image at best, and damage the microscope at worst. Don’t assume you remember where the key knobs are. You may have a different microscope than last time.
Figure 4.1 Some key parts of a compound light microscope.
The eyepiece
This is where your eyes will be. If the microscope is binocular, use both eyepieces. With binocular microscopes, you almost always can adjust the width of the eyepieces to ensure they fit the spacing of your eyes. The eyepiece contains the eyepiece lens, one of the two lenses doing the actual magnifying in a compound microscope.
The carrying arm
When moving a microscope, even if it is just a few inches, always pick it up by the carrying arm. Do NOT drag the microscope: pick it up. The microscope will have rubber feet that prevent it from sliding, so if you try to drag it, it will shake and vibrate and possible damage parts. Never pick up the microscope by any part other than the carrying arm. The other parts are generally much more fragile and prone to breaking if you try.
The objective lenses
Most compound light microscopes will contain three to four objective lenses that can be rotated over the slide. Sometimes these lenses are just called objectives. When a particular objective has been fully rotated into position, you will hear or feel a click as that objective locks into place. The objective lens is the second of the two lenses doing the actual magnifying in a compound microscope, so if it is not snapped into proper position, you won’t see the proper image. Each objective lens can usually be unscrewed from its position in the rotating turret that houses it. Be careful you are rotating the turret, not unscrewing an objective. Do NOT unscrew the objectives from the turret. Each objective lens has a different magnifying power, so the image on your slide will be magnified to lesser or greater extents, depending on which objective lens you have chosen. Each objective’s magnification power will be written somewhere on the side of the objective, although sometimes it is hard to see the number. The magnification of an objective lens will always be a whole number. There will be other things written on the side of an objective, but the one that is a whole number greater than 1 will be the magnification. You can ignore everything else written there.
The stage
The stage is the platform that the slide will be clipped on to.
Stage clips
The slide will be held in place on the stage with stage clips. Most of the time, these will clip against the sides of the slide. They do not sit above or below the slide. They are spring-loaded to hold the slide edges and lock the slide in place so that the stage controls can move the position of the slide smoothly. If the slide is not clipped in place, you won’t be able to reposition the slide to find microscopic features of interest.
Stage Controls
These allow you to move your slide while you are viewing it, but only if the slide is properly clipped in with the stage clips. Always find where these are on your microscope before you start viewing your slide. They seem to never be in the same place in two different microscopes and if you just blindly grope for them while viewing your slide, you will likely do something unfortunate to your view or to the entire microscope. There are always two dials. One moves the slide left and right. The other moves the slide up and down. Sometimes they are on top of each other, as in the binocular microscope in Figure 4.1. Sometimes they are two separate dials, as in the monocular microscope in Figure 4.1. Sometimes they are above the stage, as in the monocular microscope in Figure 4.1. Sometimes they are below the stage, as in the binocular scope in Figure 4.1. Spend a few seconds to find them every time before you sit down at a microscope.
Coarse focus
This is always the larger of the two focus knobs. You should usually only need to use the coarse focus knob once for each new slide. Use it with the lowest power objective to get the specimen approximately in focus. After that, only use the fine focus knob, even after you change to a higher-power objective. Sometimes the coarse focus know is with the fine focus knob, as on the binocular microscope in Figure 4.1. Sometimes it is separate from the fine focus know, as on the monocular microscope in Figure 4.1.
Fine focus
This is always the smaller of the two focus knobs. This is the focus know you will use over and over again in viewing slides. Don’t change the coarse focus after using it for the first time, only change the fine focus.
Condenser adjustment
Not all microscopes have a condenser adjustment knob. If there are only two knobs, as on the monocular microscope in Figure 4.1, those two are the coarse focus and the fine focus and you only have to keep those two separate. But if there is a third knob, it is the condenser adjustment knob. As a general rule, do NOT touch or adjust this knob. It controls how far the light condenser is from the slide, which should be properly adjusted before you use the microscope. If you move it, you will have it in the wrong position. If your scope has the knob, find out where it is and avoid it.
Diaphragm
This is directly under the hole in the stage where light passes through to the slide. It is controlled by a level which opens and closes an iris to let more or less light through the slide. In some specimens there is not much contrast between the colours and shades of the different components being magnified. Changing how bright the view is by adjusting the diaphragm can allow you to better see some of the details you are trying to magnify.
Lab 4 Exercises 4.1
There is a compound microscope for each student. Carry out the activities listed below and fill in the blanks as you do so.
- Pick up your microscope and physically move it to a new location. Bring it close enough that you can look into it comfortably from where you are sitting. Arrange it so that the stage is facing you and the eyepiece is rotated towards you. What part of the microscope did you grab in order to pick it up and move it?
- Where are the locations of the two stage adjustment knobs on your microscope?
- Where is the location of the coarse focus knob?
- Where is the location of the fine focus knob?
- Is there a condenser adjustment knob? If so, where is it located?
- Find the diaphragm lever. Looking in the hole in the center of the stage, what happens when you move the diaphragm lever clockwise?
- Still looking down at the hole in the center of the stage, what happens when you slide the diaphragm lever counter-clockwise?
Understanding the Compound Microscope Parts and its Functions
Compound microscope is a widely used instrument in the field of life sciences helps solve many mysteries of life. The following article will cover information on its parts and functions.
A compound microscopes helps in magnifying an image in two stages. It uses an objective lens that has many powers on a turret and an eyepiece that helps in magnifying the image formed by the objective lens. It is divided into structural parts and optical parts.
Labeled Diagram of a Compound Microscope
Structural Parts
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It is divided into three basic structural components, which can be explained as follows:
Head:
The head or body of a compound microscope contains the optical parts of the microscope.
The head or body of a compound microscope contains the optical parts of the microscope.
Base:
The base of a compound microscope is helps in supporting the microscope and contains the illuminator.
The base of a compound microscope is helps in supporting the microscope and contains the illuminator.
Arm:
The arm acts as a connector between the base and the head of the compound microscope.
The arm acts as a connector between the base and the head of the compound microscope.
Optical Parts
There are various optical parts of a microscope that help one observe the specimen or samples on a slide.
Eyepiece:
The eyepiece is the ocular lens that helps you look through to see a magnified image from the top of the microscope. The lens have a power of magnification of about 10x or 15x.
The eyepiece is the ocular lens that helps you look through to see a magnified image from the top of the microscope. The lens have a power of magnification of about 10x or 15x.
Eyepiece Tube:
The part that connects the eyepiece with the objective lens is the tube.
The part that connects the eyepiece with the objective lens is the tube.
Turret:
The nose piece that supports the objective lens is known as turret or revolving nose-piece. You can rotate it and change the power magnifications.
The nose piece that supports the objective lens is known as turret or revolving nose-piece. You can rotate it and change the power magnifications.
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Objective Lens:
You can see three or four objective lens attached to the end of the tube. The lenses range from 4x to 100x magnifying powers. To make matters simple, you can identify the longest objective lens as the one that provides the highest magnification power.
You can see three or four objective lens attached to the end of the tube. The lenses range from 4x to 100x magnifying powers. To make matters simple, you can identify the longest objective lens as the one that provides the highest magnification power.
Rack Stop:
It is a factory set adjustment that determines how close the objective lens can get to the slide. This prevents the viewer from cranking the high power objective lens into the slide. It is used only when really thin slides are used to focus a sample under high power.
It is a factory set adjustment that determines how close the objective lens can get to the slide. This prevents the viewer from cranking the high power objective lens into the slide. It is used only when really thin slides are used to focus a sample under high power.
Coarse and Fine Focus:
These are the knobs that help focus the microscope. There are many compound microscopes that have coaxial knobs. The coaxial knobs are built on the same axis as the fine focus knob on the outside. This proves to be more convenient to use as you do not need to fumble with different knobs.
These are the knobs that help focus the microscope. There are many compound microscopes that have coaxial knobs. The coaxial knobs are built on the same axis as the fine focus knob on the outside. This proves to be more convenient to use as you do not need to fumble with different knobs.
Stage:
The stage is the flat surface on which you keep the specimen to be observed. Microscopes with mechanical stage have two knobs. These knobs can be used to move the slide around, that is, left and right or up and down.
The stage is the flat surface on which you keep the specimen to be observed. Microscopes with mechanical stage have two knobs. These knobs can be used to move the slide around, that is, left and right or up and down.
Stage Clips:
The stage clips are used to hold the slide in place on the stage.
The stage clips are used to hold the slide in place on the stage.
Aperture:
The tiny hole in the stage that helps in transmitting base light to the stage.
The tiny hole in the stage that helps in transmitting base light to the stage.
Illuminator/Mirror:
The light source that is located at the base of the microscope. The mirror reflects the light from the outside source through the bottom of the stage. This helps in illuminating the sample on the slide. Many light microscopes use low voltage halogen bulbs. They have a continuous variable light control part at the base that helps in focusing in different light range.
The light source that is located at the base of the microscope. The mirror reflects the light from the outside source through the bottom of the stage. This helps in illuminating the sample on the slide. Many light microscopes use low voltage halogen bulbs. They have a continuous variable light control part at the base that helps in focusing in different light range.
Condenser:
The condenser is present at the base of the stage. It is usually connected to the iris diaphragm.
The condenser is present at the base of the stage. It is usually connected to the iris diaphragm.
Iris Diaphragm:
This part helps in controlling the amount of light that reaches the specimen. The diaphragm is located above the condenser and below the stage.
This part helps in controlling the amount of light that reaches the specimen. The diaphragm is located above the condenser and below the stage.
Condenser Focus Knob:
In order to help the condenser move up and down and control the lighting focus on the specimen, a condenser focus knob is used.
In order to help the condenser move up and down and control the lighting focus on the specimen, a condenser focus knob is used.
Functions of a Compound Microscope
Without the microscope, one will never be able to understand the world of microorganisms. The various functions of compound microscope are as follows:
Eyepiece:
The eyepiece helps you look at the magnified image of the specimen that is usually magnified by 10x or 15x.
The eyepiece helps you look at the magnified image of the specimen that is usually magnified by 10x or 15x.
Coarse Adjustment Knob:
This knob helps in focusing the specimen by adjusting the distance of the objective lens to the slide. The knob helps move the objective lens up and down till the magnified image is seen clearly.
This knob helps in focusing the specimen by adjusting the distance of the objective lens to the slide. The knob helps move the objective lens up and down till the magnified image is seen clearly.
Fine Adjust Knob:
This helps in switching from one objective lens to the other. The specimen can be easily observed under high or low magnification with the adjustment using fine adjust knob.
This helps in switching from one objective lens to the other. The specimen can be easily observed under high or low magnification with the adjustment using fine adjust knob.
Low Power Objective Lens:
The low power objective helps in viewing large specimens.
The low power objective helps in viewing large specimens.
High Power Objective:
These are used for a detailed view of the specimen and small specimens.
These are used for a detailed view of the specimen and small specimens.
Stage:
The stage helps in supporting the specimen and helps you keep the specimen on the correct location.
The stage helps in supporting the specimen and helps you keep the specimen on the correct location.
Condenser:
The condenser helps in focusing the light on the specimen.
The condenser helps in focusing the light on the specimen.
Iris Diaphragm:
This is used to help in regulating the amount of light and contrast.
This is used to help in regulating the amount of light and contrast.
Illuminator:
This helps in illuminating the specimen kept on stage.
This helps in illuminating the specimen kept on stage.
The microscope has come a long way since the experimental tubes made by two Dutch spectacle makers, Zacharias Janssen and his son Hans in 1590. Antony van Leeuwenhoek would have never imagined that one day, it would be possible to view the minute details of the cell organelles of what he called ‘animalcules’. You will find many different types of microscopes today, that help in different fields of life sciences.
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