Components of Compound Light Microscope

Mechanical parts of the microscope
The mechanical parts of an optical microscope are those structural elements with the function of giving stability to the apparatus. and that allows the optical components of the microscope to be in the right place to allow the visualization of the samples.

Next, we will review the mechanical parts of every microscope, its name, and what exactly they are for.

1. Foot or base
As its name suggests, the foot is the structure that is located at the bottom of the microscope. It is the base above which the rest of the components are located.

For the correct visualization of samples, it is necessary that the microscope be kept as immobile as possible since any slight change in position affects the task. This balance is provided by the base, which is the heaviest part of the entire microscope.

In addition, it usually includes rubber stops that further reduce instability, preventing the microscope from sliding over the work table.

2. Coarse screw
The coarse screw is a rotating structure located on the side of the microscope that causes the sample to move vertically. This component is essential for visualization, as each sample needs to be at a specific distance from the target.

Turning the screw is the first step to achieving an adequate focus of the sample, otherwise, visualization would be impossible. Everything would be out of focus.




3. Micrometer screw
As an annex to the coarse, the micrometer screw is the structure that allows, once a preliminary approach has been achieved, to adjust the distance much more precisely. The vertical movement that the sample will make is much less but it allows a perfect focus to be achieved, which is essential due to the small size of the sample.

4. Stage
The stage is the surface on which the sample to be observed is deposited. It has a hole in the center through which the light will reach the sample. Connected to the macro and micrometric screws, it moves vertically according to what we decide by rotating these screws.

5. Tweezers
The tweezers are attached to the stage and have the function of holding the sample fixed so as not to lose focus. once we are already working on the visualization. We are viewing the sample at high magnification, so any movement would cause us to lose all work.

6. Arm
The arm is the backbone of the microscope. Born at the base of this, it is the structural piece that connects all the other components to each other. It must also be very stable to avoid alterations in the position of the sample.

7. Revolver
The revolver is a rotating structure located at the top of the microscope and where the objectives are mounted. By rotating it, the user of the microscope is allowed to alternate between the different objectives. with which the microscope is equipped.

8. Tube
The tube is a cylindrical structure located in the upper part that, attached to the microscope arm, connects the eyepiece with the revolver. It is the element through which the light reaches the observer.

Optical parts of the microscope
Optical components are those that are responsible for displaying samples since the elements in charge of generating and giving directionality to the light are included.
The optical structures that make up every light microscope are as follows.

1. Spotlight or light source
The most widely used optical microscopes have a light generator although the more traditional ones have a mirror that reflects the natural light of the place where you are working. Whatever type it is, it is an indispensable element of the microscope, since the visualization depends entirely on the light. Both structures are at the base of the microscope.

In the case of having its own focus, it generates a beam of light that is directed upwards towards the sample and that will pass through it to reach the eyes of the observer.

2. Condenser
The condenser is the optical element that concentrates the light beam since the rays leave the focus in a scattered way. That is why, to be focused on the sample, they have to be agglomerated at a specific point.

3. Diaphragm
The diaphragm is a structure that, by opening and closing, regulates the passage of light towards the sample.. The condenser is usually close to the bottom of the stage and its optimum opening point depends on the transparency of the observed sample.
Very dense samples will require allowing a greater amount of light to pass through, otherwise, we would see everything dark. On the other hand, very thin samples require that we close the diaphragm more because if it is very open we would observe the sample with too much light, seeing everything white.
Depending on the size of the sample, we will choose one objective or another.

5. Eyepiece
The eyepiece is the component through which we observe the sample and, in addition, is the second phase of magnification of the microscope. The eyepiece magnifies the image coming from the objectives, so the combination of the magnification of the eyepiece and the objective tells us at how much magnification we are observing the sample.

Thus, if the eyepiece has a magnification of 2x and the objective we are working with is 40x, we are seeing the sample 80 times enlarged.

4. Objectives
The objectives are the structures by which we decide how much magnification we want to see the sample. They are a set of lenses ordered from lowest to highest magnification (with their respective increase in size) that concentrate the light from the sample to produce a real image that can be observed.

Each objective has an associated color to quickly identify how many magnifications (x) we are working on:

Black: 1x / 1.5 x
Brown: 2x / 2.5x
Red: 4x / 5x
Yellow: 10x
Light green: 16x / 20x
Dark green: 25x / 32x
Sky Blue: 40x / 50x
Dark blue: 60x / 63x
White: 100x / 150x / 250x
Depending on the size of the sample, we will choose one objective or another.

5. Eyepiece
The eyepiece is the component through which we observe the sample and, in addition, is the second phase of magnification of the microscope. The eyepiece magnifies the image coming from the objectives, so the combination of the magnification of the eyepiece and the objective tells us how much magnification we are observing the sample.

Thus, if the eyepiece has a magnification of 2x and the objective we are working with is 40x, we are seeing the sample 80 times enlarged.