What is the difference between line scan and area scan cameras?


Line scan cameras for efficient print inspection processes

In imaging there are many different types of cameras, imaging sensors, and data interfaces. There is a basic difference between line scan and area scan cameras.

Line scan cameras record an endless image one line at a time. This is done at frequencies of ten thousand pictures per second, which are put together by software. Thanks to line lengths of well in excess of 10,000 pixels, high spatial resolution is guaranteed and only a thin strip has to be illuminated. The full advantage of line scan cameras can be experienced in processes with very high belt speeds. In the visible wavelength range, they work mainly with CCD or active CMOS sensors (active because each pixel has its own amplifier and A/D converter). At the transition from visible to near-infrared wavelengths (VIS-SWIR) and in the infrared range, mainly indium gallium arsenide (InGaAs) sensors are used, but recently also colloidal quantum dot (CQD) sensors appeared on the market. Line scan cameras are also available for 3D applications.

Area scan cameras are based on rectangular sensors. Their pixels are all exposed at the same time and convert photons into electric signals. They are evaluated image by image. The latest CMOS sensors (Sony IMX411ALR) with resolutions to 14,192 x 10,656 pixels (151 megapixels) allow inspection of large wafers, solar panels, and displays. Data interfaces like Camera Link (6.8 Gbit/s), GigE Vision (10 Gbit/s), USB 3.1 (10 Gbit/s), and CoaXPress (CPX – to 4 x 6.25 Gbit/s) and CXP-12 (to 4 x 12.5 Gbit/s) ensure the corresponding broadband transfer of the image data.

Imaging professionals can also obtain more detailed information and white papers, extensive learning material, glossaries, and fascinating user reports from other exhibitors at LASER World of PHOTONICS 2019.

 
 
 
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