Direct incident light can be any form of lighting in which LEDsshine directly onto the object. Ring lighting is often chosen for this purpose. Line lighting, bar lighting or surface lighting are also possible. Disturbing reflections can occur on reflective object surfaces. A distinction is made between bright field illumination and dark field illumination. Büchner […]
One problem with diffuse backlighting is the occurrence of side light. For high-precision measurements, even better results can be achieved by using a telecentric backlight. As with the telecentric lens, this form of illumination has a parallel beam path. This is achieved by a collimator lens between the light source and the light panel.
The best diffuse incident light is obtained with dome lighting. They provide homogeneous light from all directions and are therefore often referred to as “cloudy day illumination”. They are ideal for shiny and/or uneven test surfaces, as scratches and unevenness are softly illuminated. Surfaces appear quite homogeneous and therefore structureless. It is important to keep […]
The duty cycle describes the ratio of the pulse duration(LED on) to the period duration. The smaller the duty cycle (in %), the less the LEDs heat up and can therefore be operated with higher currents (more brightness) and have a longer service life. The duty cycle is controlled via a controller.
EMC (electromagnetic compatibility) is defined in the EMC Directive 2004/108/EC as the ability of a device to operate satisfactorily in an electromagnetic environment without itself causing electromagnetic disturbance that would be unacceptable to other devices in that environment. In EMC, a distinction is made between electromagnetic emissions (EME) and electromagnetic immunity (EMS). Electromagnetic interference emission […]
Hazards to the eye from LEDs, luminaires or other light sources are classified by DIN EN 62471, edition 2009-03 (Photobiological safety of lamps and lamp systems; German version EN 62471:2008; IEC 62471:2006). The hazard can be caused thermally or photochemically. The following possible damage is considered when evaluating a light source for resulting hazards: – […]
Light guides are transparent, flexible materials, such as fibers, tubes or rods, through which light is transported. The light is mostly transmitted by total reflection at the interface of the light guide. For this purpose, the medium surrounding the light guide must have a lower refractive index n or refractive index gradient. Another option is […]
The performance of LEDs and LED lighting is often limited by the self-heating of the components. One way to increase performance is to use flash controllers or flash control units. Since camera systems, with the exception of line scan cameras and high-speed cameras, usually only record short images at a certain frame rate, it can […]
High-speed or flash lighting only emits light for a very short time, usually < 1 ms. The flash duration is shorter than the exposure time of the camera and is within its exposure time. To ensure that the flash lights up at the right time when the picture is taken, the flash synchronization must be […]
