Illumination Methods Using Dome Lights
Dome Illumination
Dome lights distribute light homogeneously over the whole diameter. The modular ring light is directed upwards illuminating the inside of the dome surface. The light is then reflected and diffused from the surface down to the target.
LMDX Dome Light
LMDX dome lights are based on the LMRX modular ring light platform. The reflective dome accessories ZMRG001 and ZMRG002 turn the light source into a traditional “cloudy day illumination” where the light is homogeneously distributed over the whole diameter. This is an excellent tool for reading inkjet or laser markings on shiny, curved and/or uneven surfaces and inspecting areas inside of holes from a close working distance. The Machine Vision dome lights are bi-color available in white-infrared and red-cyan.
Multi-UV Dome Light
LMDX Dome Light
The multi-UV dome light is a lighting solution for the detection of fluorescent materials. Their special dome shape ensures even light distribution over the entire field of vision. The integration of a long-pass filter enables seamless connection to various cameras, from simple code scanners to high-end smart cameras. It also offers the option of attaching optical filters directly to the housing to detect specific fluorescent colors.
The dome light supports both flash mode and continuous light mode. UV illumination is only available in flash mode, while white light can be used in both flash and continuous mode. Thanks to these features, both UV and white light illumination can be realized with one product. Several UV wavelengths are available, including UV365, UV395 + UV405 and UV365 + UV395 + UV405 to optimize the detection of fluorescent materials.
The special shape of the dome light in combination with the integrated long-pass filter makes the product user-friendly and safe as it shields direct UV radiation. It provides a comprehensive solution for illumination applications in the UV range and is compatible with all cameras in the visible spectrum.
Comparison of Different Brightfield Illuminations
What is the advantage when using dome illumination instead of ring illumination?
A dome light is usually mounted very close to the inspected part so that the full potential of illumination intensity is used. Due to the highly diffuse light output, the illumination intensity decreases rapidly with a bigger working distance.
Illumination Method
Illuminated Object
A ring light can be mounted at a bigger working distance to the inspected part.
Due to very diffuse LEDs, the optimal working distance is between 100 and 600 mm.
Due to very diffuse LEDs, the optimal working distance is between 100 and 600 mm.
Illuminated Object
Illumination Method
Working Distance
When increasing the working distance, the dark spot perceived by the camera is reduced in size and the illumination emitted from the dome light becomes linear along the camera axis. The effect on an engraved marking can be observed in the video.
Hole Aperture Adapter
The need of a camera hole at the top of the dome leads to a reduced illumination intensity in the center of the captured image (dark spot effect). If the industrial environment does not allow a bigger working distance to eliminate this effect, hole aperture adapters (HAA) enable the reduction of the camera hole diameter. Camera hole sizes start from 30 mm (LMDX1xx) or 35 mm (LMDX2xx) as a standard going down to 20, 15, 10 or even 5 mm as required for the machine vision system.
All hole aperture adapters are included in the scope of delivery of the dome light (LMD) and the dome accessories (ZMRG001 and ZMRG002). The 20 mm hole aperture adapter also serves as a platform for the smaller adapter diameters.
All hole aperture adapters are included in the scope of delivery of the dome light (LMD) and the dome accessories (ZMRG001 and ZMRG002). The 20 mm hole aperture adapter also serves as a platform for the smaller adapter diameters.
Dome Light without HAA
Clearly visible dark spot
Dome Light with HAA 15 mm
Reduced dark spot
Dome Light with HAA 10 mm
Faint dark spot
Dome Light with HAA 5 mm
No dark spot
Illumination Alternative – Creating the Dome Effect Using Bar Lights
Besides using the LMD dome lights, a Machine Vision dome effect can also be created using LBA bar lights inside a box. The bar light illuminates the ceiling of the box which should be made of a white, matte surface, thus creating a homogeneous field of view which is perfect for illuminating complex surfaces.
