Compound vs. Stereo Microscopes
What are the differences between stereo and compound microscopes? And what are all the different kinds of microscopes that you could consider getting? The basic premise of a microscope is simple. By using magnification technologies, you increase the visibility of an object to reveal new textures, insights, and patterns. But compound and stereo microscopes do this in drastically different ways.
In this post, we’re going to look at some of the differences between stereo and compound microscopes. As we’ll see, the basic difference is the way that the stereo and compound microscopes use light.
Stereo and Compound Microscopes
The short version: stereo microscopes rely on light from above, and cap the magnification powers at a lower level. Compound microscopes rely on light from below, shooting through the object, which gives you a higher magnification power.
Differences in Microscopes
A stereo microscope is also called a dissecting microscope, because they are often used to dissect plants and animals.
A compound microscope has two kinds of lenses (hence the name compound). One of the lenses is an objective lens, and the other is an ocular lens. A simple microscope has only one lens, and basically works the same as a magnifying glass.
Stereo microscopes have two lenses, just like a compound microscope does. The lenses are also objective and ocular. Stereo microscopes are better for larger objects, like an entire insect or a rock. But compound microscopes are built for thinner, more delicate structures and tissues. Compound microscopes give you a much greater magnification. Compound microscopes can increase the visibility of an object up to 1000 times the normal visual representation. While a stereo microscope caps at about 300 times the normal representation.
Compound microscopes shoot light through the specimen that you’re looking at. If the object is too dark or too opaque, you won’t be able to see many details using a compound microscope. A stereo microscope works differently. They use light from above, and are designed to let you see the texture of an object without slicing it into thin sections that light can penetrate. Stereoscopic vision gives you the magnification that you need to check out things like rocks, which a compound microscope could not do.
How Does a Stereo Microscope Work?
Stereo microscopes are built for low-level magnification only. They basically use light that travels downward instead of upward, which reduces the type of image that can be produced.
Traditionally, stereo microscopes are used for scenarios where you cannot change the fundamental shape or texture of the object that you’re viewing. Surgery, computer manufacturing, and watch making are a few examples of this. You can’t exactly slice a sliver of the heart off to throw it under the light of a compound microscope! Stereo tools allow you to get a closer look at an object, regardless of transparency.
How Does a Compound Microscope Work?
Compound microscopes are basically a tube that has a number of pieces of glass that bounce light up to a visible image when you look through it. Compound microscopes can get up to 1000 times visual magnification.
They use basically a system of mirrors and lenses to fire beams of light up through the tube, intensifying the image down below. Light starts at the bottom, in the old microscopes it was daylight but modern microscopes use a bulb, and travels up through the specimen. The stage is the horizontal platform that houses the object you’re looking at. Generally, there are two thin glass sheets that flatten out and hold the specimen which you’re looking at. Light then travels from the base, through the stage, through the specimen, up through the objective lens. The objective lens is usually a series of lenses which provide magnification. The wheel on the side of the microscope then controls the lenses through the tube. A secondary lens system, the eyepiece lens, magnifies the already-magnified image that comes up through the tube.
Other Kinds of Microscopes
Compound microscopes are often curved, because this can be more natural for the eyes, but some people prefer the straight compound microscope, which allows you to look straight down on the specimen.
The standard kind of compound microscope is a biological one, which uses light to transmit the image up through the magnification. But there are other kinds of compound microscopes as well.
For distance magnification, there are scopes and binoculars. Field glasses, also called binoculars, are a handheld device that focuses both of your eyes onto an object in the distance. Spotting scopes are basically a curved scope that allows you to focus on objects in the distance. They are usually stabilized with a tripod.
Advances In Microscope Technology
There are tons of ways that scientists are experimenting with new types of microscopes. Widefield microscopes are using more intense light, confocal microscopes can illuminate a pinpoint which creates higher resolution, and light-sheet microscopy scans use a very thin laser instead of a point which can track cells and tissues.
Additionally, structured illumination allows live cells and higher contrast images through structured, super-high resolutions. The basic premise of a microscope is simple: use technology to get a better look at some sort of object. There are new ways of doing that which don’t rely so heavily on a few panes of glass.
Maybe you’ve also heard of the electron microscope, which literally uses a beam of accelerated electrons to magnify an image through an illumination process. Electron microscopy can use the high resolutions for biomedical research, in particular. Electrons can use the wave-particle duality of fast-moving electrons to illuminate an object. Specimens for the electron microscope are placed in a chamber that has no air. Electrons don’t travel well in air, so it has to be vacuum tight to prevent the image from getting scrambled.
Then, instead of using a lens to illuminate the object, electromagnets fire an electron beam which bends around the object and is then produced as an image on a screen. The specimen is placed on a copper grid, which allows the electrons to pass through the specimen and collect an image of it. The projector lens then becomes visible when the beam hits the fluorescent screen at the other end. The image can then be viewed through a TV.
Digital stereo microscopes use visual imaging technology to display the microscopic view on a screen instead of in an eyepiece. It’s a much more convenient way to use a microscope with multiple people or for a presentation. Additionally, many people find the convenience of the digital screen to be super useful.
Digital microscope technology used to be a lot more expensive, but it is getting more affordable. For example, the ITI-350L LCD USB Digital Microscope is super affordable, and gives you up to 5 MP of 12 MP interpolation. It can output to a TV, and it can be connected to a computer for software-powered measurement. Plus, it uses a rechargeable lithium battery for power!
But not all microscopes are on lab benches, waiting for you to bring specimens to the table. The ITI-350P Portable Digital Microscope, for example, has a micro SD card and a portable construction which allows you to take it on the go. Examine objects in thrift stores, use it to see plants in nature, and check out everyday objects.