What are high-speed cameras?
Digital imaging technology constantly evolves. Next to the resolution, the imaging speed of digital cameras is of great importance for many imaging applications. Typically, digital cameras are categorized as high-speed cameras if they provide imaging speeds of at least 1000 frames per second (fps). The maximum achievable imaging speed is constantly advancing. At the moment, cameras with maximum achievable frame rates of up to several millions of images per second are available.
Many high-speed cameras are equipped with imaging chips that allow cropping. Cropping enables the reduction of the image resolution to achieve higher imaging speeds. Some key factors for high-speed cameras are the imaging speed, specified in frames per second (fps), and the light sensitivity (ISO). The benefit of the imaging speed is obvious. The faster you can record images of dynamic processes of deformation or motion, the more accurately you can study the changes observed. The benefit of the light sensitivity of the imaging chip might not be as obvious in the first place, but it is an important factor as well. Capturing highly dynamic events requires a lot of light to ensure that there is enough contrast in the images later. If you don’t have enough light, your images might be just too dark to analyze them. Having this in mind, the light sensitivity of the imaging chip gets a practical meaning. The higher the light sensitivity, the less light you need to still get images with enough contrast. This is especially useful when it comes to measuring high-speed motion or deformation of material specimens which are typically very small in size. It can get difficult to arrange all the light sources and point them to the small specimen in the confined spaces of a materials laboratory. So, every lamp that you can spare, will make your life easier and the setup of the 3D measuring sensor more convenient.
Another advantage of an image sensor with higher light sensitivity is that exposure times can be kept shorter. Very short exposure times are required especially for high-speed tests in materials research but also for crash tests in the automotive industry. If the exposure times are too long, there is a risk that the rapid movements or deformations that are to be investigated can no longer be imaged sharply. In these cases, the term “motion blur” is used. Such motion-blurred image data is then not suitable for evaluation using the digital image correlation method.