Trends in CCD to CMOS image sensors, image processing, optics, and interfaces for OEM industrial cameras and vision systems, Part 2

Posted by Gretchen Alper on Tue, Aug 11, 2015

For part one with details on trends in image sensors and image processing, click here.


Changes with Optics

The state-of-the-art Complementary Metal Oxide Semiconductor (CMOS) sensors entering the market have low noise and high Dynamic Range (DR). This high Dynamic Range allows applying more gain maintaining the present day’s requested camera output resolution expressed in bits. As a result the aperture of the lens can be relaxed and selected to balance lens aberrations and lens diffraction. When needed the degree of freedom can even be extended by using a Neutral Density (ND) filter.

The recent developments in CMOS image sensor technology gives more freedom to select those lens parameters that enhancing its performance, e.g. the Modulation Transfer Function (MTF).

With some applications it might even be possible to capture the complete DR of the scene expressed in luminance without the need to control the light flux by means of iris diaphragm or variable ND filter. The latter has tremendous advantages, to mention:

  • A lower cost lens
  • A significantly more economic lens because of reduced Mean Time Between Failure (MTBF) due to increased reliability as there is no need for moving parts. The MTBF will be that typically encountered for electronic equipment.
  • A lens with on average improved image resolution because of the fixed lens aperture optimized for optimal contrast.
  • A lens with improved image uniformity, in a sense that the radial falloff in image intensity will be less because of the reduced lens aperture.
  • A lens with significantly improved repeatability, because all functions are implemented digitally.
  • Last but not least, a lens with a more compact outline, which is more power efficiency and easier to install.


The above is just an example how recent developments in sensor technology combined with image processing, although in this case limited to gain only, can help to optimize the electro-optical imaging chain. In the near future we expect further integration of optics, sensors and image processing with more optimal integral solutions as a result. In this sense, zoom lenses will become partly or completely digital as a tradeoff between amongst others performance, volume, reliability and cost. This trend is already common practice in consumer products, with its high degree of integration, but will also enter the industrial markets.


Future of Interfaces

While there will likely be no new systems designed around Camera Link, there are many legacy systems that will continue using Camera Link. Many system designers are trying to move towards USB3 Vision or GigE Vision to avoid a frame grabber when either the cable length or speed limitations, respectively, are not a problem. GigE Vision is becoming especially challenging as even HD resolutions require a higher data rate than 1 Gbps and 10 GigE is not taking off since it is not driven by the consumer market. USB3 Vision will likely continue to gain more market share, especially with planned speed increases. Important limitations however are the limited cable length and that systems with multiple USB3 Vision cameras running at high speed are complex to design so that the planned costs reduction may be less than anticipated.

CoaXPress has received wide acceptance in many high-end, high-speed applications because of the data rates and cable lengths enabled. But also other than industrial markets (like military and medical) show interest in CoaXPress. The defense market in particular appreciates the rugged cable and connectors, support of any video format one can think of, and the fact that only one coaxial cable is needed to interface the camera – power, video data, communication and triggering all share the same cable.

State-of-the-art CoaXPress implementations show that it is possible to make very compact and low power cameras.

Because of the versatility of the standard, we expect that CoaXPress will continue to gain more market share.


What are some of your thoughts on where the industrial vision market is going?

Topics: Interface Technology