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As the leading innovator in the field of precise illumination for machine vision, Siemens has mastered the highly complex nature of machine vision illumination. Cameras see light as it is reflected from an object. Light is reflected differently from a metal ball than from a flat white label or a printed circuit board. The purpose of machine vision illumination is to control how the object appears to the camera. With these differences in mind, we study the geometric patterns of the light reflected from the part and designs lighting systems to control glare and reflection. Developed with a sophisticated knowledge of ray tracing and uniform lighting, NERLITEs enable vision engineers to work with clearer and crisper images. To meet the varied needs of machine vision applications, Siemens has created three distinct lines, with increasing levels of sophistication: DOAL, SCDI, and CDI.
| Diffuse On Axis Light—DOAL |
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 With the DOAL, light rays reflect off the beam splitter directly on to the object at nearly 90°. With this approach, specular surfaces perpendicular to the camera appear illuminated, while surfaces at an angle to the camera appear dark. Non-specular surfaces absorb light and appear dark.
 
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| Square Continuous Diffuse Illuminator—SCDI |
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 The SCDI works on the same principles as the DOAL, but with added uniformity for non-planar surfaces. With the SCDI, light rays reflect off the beamsplitter and the lower chamber, increasing the solid angle of illumination. The light source is tilted parallel to the beamsplitter increasing uniformity.
 
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| Cloudy Day Illuminator—CDI |
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 The CDI is ideal for the most complicated uneven and specular surfaces, because it offers the greatest degree of light coverage--nearly 170°. With the CDI, light rays come from two different sources, reflecting the light in as wide a hemispheric pattern as possible.
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| Which NERLITE is Right for You? |
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There are essentially three questions to ask when you are determining which NERLITE is appropriate for your machine vision application:
1. What geometry of light is required to illuminate the features?
2. What type of light source (e.g., halogen, LED) best illuminates the features?
3. How large is the field of view?
How you answer these questions determines which NERLITE product is best suited to your needs.
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