Infrared LEDs are igniting the explosion in machine vision applications
All machine vision applications use CMOS or CCD cameras to “see.” They detect light that is reflected, or scattered, from an object. But, relying solely on variable ambient light for object illumination isn’t good enough; a better signal to noise ratio requires irradiating the object with many watts of light. In many cases that light needs to be totally invisible to the human eye. That is now possible, particularly with the invention of the 940 nm wavelength LED.
Such recently developed high-power infrared (IR) LEDs are enabling new machine-vision applications, particularly in surveillance (CCTV, biometric access control, automatic number plate recognition, night vision) but also in 3D cameras, 3DTV, automotive-vision systems and factory automation.
Besides being invisible, longer-wave radiation — in the so-called “near infrared” region of the electromagnetic spectrum — oscillates less frequently than shorter-wave radiation and thus generates less interaction with the illuminated object. It is therefore capable of penetrating deeper into the material and generates fewer surface reflections than short-wave light. When using IR radiation it is sometimes even possible to look through an object.
Thanks to high-power IR LEDs, machine vision technology is quickly becoming a mainstream engineering discipline, with applications in many end markets. IR LEDs aren’t only for remote controls and opto-couplers, any more.
But, it requires some engineering to implement: Choosing the right IR illumination for an application requires an understanding of the several parameters, among them object size, distance from the camera and desired resolution.Infrared LEDs Maintain The Night Watch is a good introduction to the brave new world of machine vision. Get a handle on it. Continue reading