DataLight illuminators for lighting in dark field

Main page▹Products▹DataCam Cameras and DataLight Lighting Units	10.8.2010 \|

The choice of the right way of scene lighting decides about successfulness of solution of machine vision tasks and visual inspection. DataLight DF15 lighting units can help us solve surprisingly many problems with illuminating transparent, shiny and embossed plain objects. These illuminators can e.g. highlight unclear prints of integrated circuits and even a dust on a mirror. Let's see what the principle of lighting in dark field is and how can these illuminators be useful for us.

When illuminating shiny objects, we often must solve problems with unwanted reflections, in which the design of the image completely fades. We usually follow our intuition and after a moment of experimentation place and direct the illuminating unit so the biggest reflections aim outside the camera's field of view. This is how to place the illuminator into dark field.

The illuminator in dark field lightens the scene from almost orthogonal direction to the axis of the lens

The usage of common illuminators has its own limits, for visualizing very slight embossments, it is needed an illuminator, which directs light only with small diffusion around the chosen area. It is also necessary to illuminate an object in one plane from all sides at the same time. When illuminating only from one side, important parts of relief can disappear in the image. The best service here does the circular illuminator in dark field. The option of choosing color is useful too - by using a colored filter of the same color in camera, we can significantly suppress the influence of unwanted surrounding lighting a gain very detailed and contrast image of watched relief. This kind of illuminator type DataLight DF15 is in following pictures. The ring's inner diameter of this illuminator is 15 cm, so we can illuminate relatively big objects.

DF15 has the same connection and control options as the other DataLight illuminators
The location of four mounting holes in aluminous body corresponds with the other illuminators as well

A small demonstration of this illuminator's possibilities is displaying a mintage relief on the reversed side of a shiny coin.

The coin illuminated by the DataLight DF15 illuminator with red light and an attempt to illuminate this coin with a common flat illuminator

Gained image has high purity and quality of expressing details. By camera's virtual device in the environment of Control Web system, this image can be further processed very easily. Several examples of results of inbuilt filters is introduced here.

The visualization of the mintage on a coin's surface after edge detection
$The fracture frame in mintage$
The fracture frame in mintage

An example of detection of contrast differences
An example of picture dilatation into enveloping regions

The illuminator is powered by 12 VDC power source. From one power source is possible to power several steadily shining and flashing illuminators at the same time. Attaching coils are on the illuminator's body placed identically with the other illuminating units. The illuminator's power consumption at maximum brightness setting reaches about 4W.

DataLight DF15 illuminator with red light
Dimensional drawing of DataLight DF15 illuminating unit

The lighting in dark field is a perfect solution for object's edge and border visualization and slight textures on object's surfaces. As all other DataLight illuminators, the DF15 is fully controlled through DataCam cameras. So it is easy to create combined lighting with switching over lights or scene lighting from single illuminators according to demands and solve very complicated tasks of visual inspection at minimal expenses.

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