To digitally take a photo, a modern camera needs to capture light and convert it to digital information.
To do this, a camera would require a sensor that accurately and speedily records photons from the environment.
You are probably already aware of the CMOS sensor used in smartphones and consumer digital cameras.
Image Credit: John Carney/Wikimedia Commons
These camera sensors are known as CCDs.
So, what exactly are CCDs?
How does it work, and how is it used?
Let’s talk about it.
What Is a CCD (Charge-Coupled machine)?
CCDs were the gold standard for camera sensors from the early 80s till the late 2000s.
However, CCD sensors aren’t exactly obsolete.
Despite all these disadvantages, CCDs are still thriving in various industrial and scientific applications that need machine vision.
This is because CCDs still provide higher quality low-noise images that these areas of specialized photography require.
So, what exactly are these specialized areas of photography that still use CCD?
Space Photography
Taking photos of space is best done on CCD cameras.
Near-Infrared Imaging
CCDs are used in various industrial imaging applications, one of which is near-infrared imaging.
But how exactly do CCD sensors provide such qualities?
You’ll first need to learn how CCD sensors work to understand this better.
How Does a CCD System Work?
CCD is just one of the varioustypes of camera sensors.
A tiny positively charged capacitor then acts as a bucket that collects and stores the released electrons.
A unit of this thin silicon wafer on top of a tiny capacitor is known as a photosite.
All the stored electrons from the capacitor are what make the charge.
When the camera shutter closes, all the charge from the photosites is transferred to a sense capacitor circuit.
In contrast, a CCD only uses one amplifier circuit to amplify signals.
Another disadvantage of using local amplification at high speeds is that it causes unevenness to the imagery.
CCD sensors don’t have such problems because of their linear process when processing charges in each photosite.
After the charge-to-voltage conversion, the digital signals are still too low for a processor to use.
To boost the digital signals, a signal amplifier is used.
This amplified signal is then sent to an image processor which then assembles the image.
