Stray light in imaging systems is known by many terms—veiling glare, ghost image, lens flare, and image glare, just to name a few. In its most general sense, “stray light” refers to any unwanted light that ends up in the image formed by a lens. For most of us, our exposure to stray light probably comes from using our cell phone cameras, where the flares and ghost images that appear when taking a picture of a bright light is a cool photo effect at best and a minor annoyance at worst.
However, for manufacturers and end users of cameras intended for automotive and industrial applications, being able to consistently identify particular features or specific objects—such as a pedestrian who appears in your blind spot while driving—is critical to the function and safety of the system. For those applications, unexpected stray light that obscures details in the image can be a catastrophic problem if not identified and addressed early on.
When evaluating the performance of a new imaging system, most people immediately think that measurements like Modulation Transfer Function (MTF), distortion, or maybe even encircled energy will adequately identify any issues. Stray light is usually an afterthought that is only measured once it’s been identified as a problem, mainly because people aren’t aware that stray light is potentially a critical problem for their system.
If you have a lens for a high dynamic range system, particularly for an automotive application, Optikos offers several solutions to help you avoid encountering stray light issues down the road. Optikos standard metrology products like the LensCheck™ VIS can qualify the stray light present in your lens, as well as perform all of the other typical image quality measurements that are needed to ensure that your lens is performing correctly. For times when your budget is tight and time is of the essence, the metrology engineers in our IQ Lab™ testing services department can perform the testing for you, using Optikos standard products in our state-of-the-art metrology lab. And if you have a stray light problem but don’t know how to fix it, our experienced team of optical design engineers can assist with the necessary design changes to reduce stray light and build confidence in the performance of your system.
If you’re interested, we have even more to say on the subject! Learn more about stray light testing in our Stray Light Measurement article.
Written by Hillary Balonek, Optikos Corporation