Digital microscopes use a built-in camera to view and save magnified images of samples. They can be connected to a computer or have a built-in monitor. Digital magnification can be limited by the size of the viewing screen, but digital models have the added benefit of capturing and displaying images. They are often more affordable and can offer additional functions such as 3D display and LED illumination.
A digital microscope is a traditional optical microscope with a built-in charge-coupled device (CCD) camera and is used for magnified viewing of samples and specimens. These microscopes can usually be connected to a computer so the images they produce can be saved to a hard drive for later inspection or displayed on a monitor so several people can view a specimen at once. Using a combination of technologies, digital microscopes play a crucial role in research and education.
How do they work
Most digital microscopes are built on the same foundation as other light or light microscopes. A sample is placed under an objective lens; an attached light source is usually used to make it easier to see the sample. The objective lens magnifies the sample and brings it into focus inside the microscope tube. In a stereo microscope, the eyepiece, also called the ocular lens, magnifies the image again, making it visible to the observer. A digital microscope may not include an eyepiece, but instead use a digital camera to focus the image.
Actions
The original digital microscopes required the use of a computer to view images. A box at the top of the microscope included a cable so it could be plugged into a computer and software interpreted the image and displayed it on a monitor. Microscopes of this type are still available, most of which include USB cables.
Other digital microscopes don’t require a computer. Instead, a small monitor, usually at the top of the microscope where the eyepiece would traditionally be, displays an image of the specimen. Some include a separate LCD monitor, which can allow for larger images. All-in-one models like this one usually include a hard drive so images can be stored and transferred.
Portable digital models are also available. Magnification levels with these small devices are usually limited and they typically need to be connected to a computer to see the image. The portable nature of these microscopes can be a major advantage, however, as the specimen usually doesn’t need to be moved or altered in any way. The camera could also be placed in small spaces and at unusual angles that the human eye couldn’t reach.
Combined digital and stereo microscopes include eyepieces so they can be used like traditional microscopes, but have a built-in camera that allows for image transmission and saving. In most cases, the magnification of the eyepiece determines the level of magnification of the final image. There are also camera kits available that connect to a separate stereo microscope, turning it into a digital one.
Digital enlargement
Both stereo and digital microscopes depend on the objective lens optics for much of their magnification. While stereo microscopes rely on the optics in the eyepiece to make the image visible, camera resolution and monitor size determine the amount of magnification possible with a digital microscope. This type of microscope does not necessarily include an eyepiece, it may be possible to capture images at much higher optical magnification. In addition, the image can be further digitally enlarged, especially with a high resolution camera.
Digital magnification, or zoom, manipulates the image to make it larger. When the image size is increased, the small dots of color that make up the image, called pixels, increase in size. Since this can make the image blocky, special algorithms are used to add new pixels and interpolate their value. While this can in theory reduce image quality, most digital microscopes have high-resolution cameras, so the images they produce can be as good or better than stereo light microscopes.
While it is possible to magnify a digital image more than when viewed through an eyepiece, that magnification is limited by the size of the sample that can be reproduced on a monitor. Most all-in-one microscopes have relatively small viewing screens, sometimes as small as 3.5 inches (8.89 cm) or smaller. Even larger units often include a 15-inch (38.1 cm) monitor, which still limits image size. In most cases, this means that digital microscopes provide just over half the magnification of comparable stereo microscopes.
Stereo versus digital
Both stereo and digital microscopes come in a range of magnifications and qualities, and each has its pros and cons. Despite the disadvantages of image magnification, digital models have the added benefit of being able to capture and display images. Specimen images can often be printed easily, and some digital microscopes provide resolutions up to 54 megapixels. For people who have to use the microscope regularly, being able to see the image on a screen can also create less eye strain.
Compared to stereo microscopes, even basic computer-connected digital microscopes are often more affordable and can be used for more purposes. The ability to manipulate the image digitally means that more can be done than just viewing and printing; some scientific models are characterized by a high dynamic range, which provides more contrast in the images, and functions of rotation and 3D display. Some models also provide overhead LED illumination similar to that of tissue culture microscopes.
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