Is Higher Camera Resolution Better In A Digital Microscope?

How does the required camera resolution is related to the imaging? Is it true that the higher the resolution of the camera is, the better the image quality of the microscope? These questions occur to you when you choose a microscope. Today Shanghai Unity Instruments would like to make an introduction about the relationship between microscope camera and its resolution.

In the fiercely competitive digital camera industry, manufacturers are chasing each other, hoping to beat the competition by constantly improving, and currently, the world record for a professional medium format digital camera is over 60 megapixels.

Over the years, digital photography has been caught in a never-ending mad race for pixels with no end in sight, but in microscopy, the camera with the most pixels is not necessarily the best. The area of application and optical power of a microscope are key factors in determining which camera will provide the best image, and an important measure of microscope resolution is the numerical aperture (NA), or the ability of the optical system to concentrate light.

The larger the lens and the larger the diameter, the higher the light gathering capacity of the camera or telescope, a world record that is currently held by a brand new 10.4 meter diameter lens from Las Palmas Observatory in Spain. But a lens that large in diameter is not possible for a microscope. Inserting a medium with a high refractive index between the lens and the sample can effectively improve the light gathering ability, but generally speaking, a good dry lens is limited to a numerical aperture of about 1.0, while a good immersion lens is limited to about 1.45. Sometimes, depending on the zoom setting, the numerical aperture of a stereomicroscope is in the range of 0.01 to 0.2.

Constructing a stereo objective with a higher numerical aperture is very difficult because you must stay within the 24mm stereo baseline to avoid changing the geometry of the stereo microscope system.

At low magnifications, the microscope typically transmits more detail than the camera captures. At high magnifications, the optical system limits the amount of detail the camera can capture. At 1X magnification, the instrument is capable of transmitting 14.3 million pixels to the camera, while at 16X magnification, the aforementioned pixels are reduced to 2.6 million pixels.

How do you explain this apparent negative effect? The answer is: it is related to the field limitations, which are relatively small at high magnification or zoom settings. When using a coaxial illuminator, look at the bright circle on the specimen, it shows clearly, the higher the magnification, the smaller the spot becomes, and the more detail you can observe as you zoom in on the detail or switch to a lens with a higher numerical aperture.

If you need to use a high magnification in most cases, the optics will be limited to about 3-5 million pixels, which can be transferred to the camera's sensor, while setting the camera to a high magnification, such as 12 megapixels, will produce a larger image but no other information.

In fact, choosing a microscope does not mean that the higher the resolution is, the better, or the more expensive the microscope. The point is to choose the right microscope, although some microscopes are not expensive, but the cost performance is relatively higher.

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