Why does the microscope output monochrome images?

Perhaps you have observed biological models through microscopes in a science lab in high school.

There are several different types of microscopes, including simple microscopes, dual microscopes, stereo microscopes, electron microscopes and many others. All of them are used in different situations: some in schools, others in research rooms, where scientists examine microscopic things, such as the eyes of a fly.

If you have never seen images from a microscope, here are a few examples:

Did you notice that all of these images are colorless?

It is often believed that images produced by microscopes are colorless, ie, they are black and white. And yes, at least to a certain extent.

So, do all microscopes produce black and white images? If yes, what is the reason behind it?

Microscopes can produce color images

As mentioned earlier, microscopes have different types and sizes, and some of them produce color images. Take the optical microscope as an example.

Optical microscope.

The magnified image that the optical microscope produces contains colors. In fact, if you use any conventional optical microscope with magnification up to 500 times, you will be able to see the color in that magnified image.

However, when you exceed a certain magnification level, the color will begin to disappear from the image (enlarged). That's because to look at something under a microscope, the object must have a very thin cross-section. In addition, it also needs to be thin enough for light to pass through it (usually).

However, if you take a sample that is too small and thin, it will not have enough material to add color to the light. Think of it this way: when you look at a drop of water, it seems completely colorless, but when you look at the ocean - basically a collection of billions and billions of colorless water droplets - it seems is a magnificent blue.

An ocean is made up of water droplets that are colorless, but are green (or even green).

Similarly, when you look at a carrot with the naked eye, it is orange or reddish, but when you take a small slice of the carrot itself and observe it under a microscope, the color Orange almost disappeared.

This is why you do not see colors in the optical microscope, even if you put a color template under the lens.

The electron microscope is completely different. They create gray-scale images of specimens, that is, exaggerated images in black and white. Why so?

Microscope: Photon and Electron

When we look at specimens through conventional optical microscopes, we can see their meticulous details because light reflects on their surface and reaches our eyes. More specifically, it is the photons present in light that reach our eyes and help us see the magnified image of the specimen.

This is the "ray diagram" of an optical microscope.

However, when you have to observe really small things, such as the inside of an insect's eye, the optical microscope will not help you much. In that case, you need an electron microscope.

The electron microscope, as the name implies, works with the help of fast-moving electrons, unlike optical microscopes (using photons).

We think briefly that the electron microscope uses an electron beam to reflect back from the specimen. Then, the "structure" of the reflected electrons will be used to create a 3D image of the magnified version of the specimen.

This is an image created by an electron microscope.

Why does the electron microscope produce black and white images?

The reason is quite basic: color is a characteristic of light (photon), and because the electron microscope uses electron beams to reflect the specimen, no color information will be recorded. The area where electrons pass through the specimen is white, and the area where the electrons do not pass is black.

So what you see when you look at the image created by an electron microscope is basically a contrast image, which is why the image is black and white.

You can always add "fake" color to images created by electron microscopes, but the colors added to the image are only used to make the image look "eye-catching" rather than terminated. relate to the actual color of the specimen mentioned.

Now scientists have designed an electron microscope to create color images of a specimen. However, the images it creates contain only two colors - red and green. With a few adjustments, the researchers hope to be able to add more colors, allowing them to create vivid, vivid images of fly eyes!