Do you have questions about digital imaging? Since digital imaging is a popular tool for capturing specimens under a microscope and preserving slides, we’re often asked questions about it.
Here, we’ll answer some of the top questions about this in-demand technology.
What is digital imaging?
Digital imaging is a broad term used to describe the electronic recording of images. You can capture just about anything digitally—from a sunset scene, to a microscope specimen, to a scanned document.
What is a digital image?
A digital image is made of a series of pixels, or picture elements. The computer reads the image file and displays the pixels to form an image on your monitor.
What are the advantages of digital imaging?
There are four core benefits of digital imaging for microscopy:
- Permanent record: You can make infinite copies of the same digital image without losing image quality. As a result, digital imaging helps you preserve research slides and avoid issues with samples degrading.
- Image sharing: Digital images can be sent electronically to remote colleagues, helping you save on the shipment fee of mailing a slide for a collaborative project.
- Image adjustment: Using editing programs like our cellSens imaging software for microscopes, you can easily manipulate original digital images to fix issues like poor contrast and excessive noise in just a few clicks.
- Analyze quantitatively: Digital imaging provides data for quantitative image analysis, which can help you glean new insights. For instance, you can compare data points to previous imaging results in your database.
How can you improve digital imaging quality for microscopy?
To improve the quality of your microscopy images, choose appropriate optics and cameras with capabilities that match your application.
We offer online resources to help you find microscope objectives and cameras for your experiment. A great place to start is right here on the blog. Be sure to check out these blog posts for guidance: How to Choose the Right Microscope Objective: 10 Questions to Ask and 4 Tools to Choose the Right Microscope Camera.
Which microscope digital camera capabilities are most important?
There are numerous factors that contribute to image quality. In general, you can start with camera resolution and sensitivity. Sensitivity is how well the camera sensor detects light from the sample. Resolution is the amount of detail a camera can capture. But as we mentioned before, these capabilities must align with your optics, system, and application.
Consider this example: a high-resolution camera is a poor match for a low NA objective since it cannot recover the sample structure information lost through the optics. The reason is, the light spreads wider than the camera’s pixel pitch. In this case, a lower resolution camera will work with a lower NA objective.
Or, say you need to observe in the 700–900 wavelength (nm) range. It is important to select a camera that can sense these longer wavelengths.
There are many other factors to consider, so be sure to check out our white paper: What to Consider When Choosing a Microscope Camera.
Which type of microscope camera sensor should we choose?
There are several types of sensors with their own pros and cons:
CCD is an acronym for charge-coupled device. In simple terms, a CCD is a semiconductor chip with light-sensitive areas used as a sensor in digital cameras. CCD sensors work by capturing light and converting it into an electrical charge, which provides the digital pixel data that forms an image. Historically, CCD sensors were the best choice for scientific applications. But as new sensor technology emerges, this older technology is slowly becoming less common.
EMCCD stands for electron multiplying charge-coupled devices. EMCCD is a type of CCD sensor that amplifies the low-light signals above the CCD read noise. In conventional CCD, very low signal levels typically fall below the sensor read noise, which limits their imaging capabilities in applications that demand rapid frame-rate capture at extremely low light levels.
EMCCD cameras are known for their ability to detect weak light—so you may hear them referred to as low-light cameras. Since they feature high sensitivity, they are useful tools for capturing fast biological phenomena at very low lights.
CMOS stands for complementary metal-oxide semiconductor and is the successor to CCD technology. The first and most important difference between CMOS and CCD is the readout architecture of the signal electron.
Thanks to the multi-readout amplifier for an individual photo-sensing diode, CMOS has a significantly faster readout speed than CCD. The tradeoff of fast readout is rolling shutter distortion. Since CMOS scans across the image rapidly to collect data rather than capturing every pixel at once, the exposure time difference can sometimes result in distortion.
In contrast, CCD sensors can avoid this distortion by collecting incoming photons while storing the charge, enabling it to read out every pixel at the same time.
While CMOS historically provided a lower signal-to-noise ratio compared to CCD, today you can find many high-quality CMOS cameras. In addition, the introduction of global shutter CMOS overcame the distortion caused by rolling shutter.
sCMOS is an acronym for scientific complementary metal-oxide semiconductor—often shortened to scientific CMOS. sCMOS is a type of CMOS sensor with a large pixel size and quiet noise performance. It offers more sensitivity than conventional CMOS. Usually we cool sCMOS to minimize the dark current to achieve higher signal-to-noise ratio, just like we did for cooled CCD sensors.
The most important difference between sCMOS and EMCCD cameras is that sCMOS cameras lack the capability for long exposure. EMCCD cameras are preferred for long exposure or bioluminescence imaging applications with weak fluorescence signals, while sCMOS cameras are popular for their ability to work with a variety of imaging techniques.
The most suitable digital camera ultimately depends on your specific application, so don’t hesitate to contact us if you have any questions.
Related Content
What to Consider When Choosing a Microscope Camera
