Main Product: Lamp Ballasts

Light Control Considerations:



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Metal Halide


Advantages:
Metal Halide lamps are rugged and powerful, and emit white light; however, the spectrum is not continuous. It is composed of discrete color segments that combine to give the appearance of "white" light. Nevertheless, cameras can be adjusted to work well with these lamps as demonstrated by the successful televising of sporting events.


Metal Halide's Usefulness
Metal Halide light-sources are available in many package sizes that are especially useful in Machine Vision installations. Lamps are available from 250-watts to 1000-watts.


Metal Halide's Suitability
Even though Metal Halide light-sources come in a variety of shapes and sizes, only some can be actually used in Machine Vision lighting systems. Generally, the shorter the arc and the greater the ignition-voltage required, the less suitable the lamp is for Machine Vision applications.


Special Consideration: Spatial Distribution of Colors
It is important to remember that the colors in a Metal Halide lamp are spatially distributed. There is a central arc of blue (mercury) surrounded by a cylinder of green (thallium) and successive concentric cylinders of orange and red. This separation of colors means that focusing the light will result in a variation of color temperature across the projected light-field.

To counter this:
Diffusers should be used to mix the colors for a consistent color temperature,
and...
The lamp should be also operated horizontally to keep internal color at optimum.


The MERCRON Advantage...
MERCRON's light feedback system keeps the arc lamp operating at a steady output, and in doing so, fixes the color for the selected power level.


Rule of thumb:
If the arc length is short and the ignition voltage exceeds 5000-volts, the lamp cannot be used. Moreover, only HID and HQI greater than 250-watts can be driven to emit CONTINUOUS, RIPPLE FREE LIGHT to meet MERCRON's standards for precision illumination. The high-pressure HMI and HTI lamps cannot be operated to emit continuous light.


One Excellent Exception

The Osram HQI 400 and similar HQI lamps work well. It has a color Rendering Index (CRI) of 93. The HQI 400 is also unique in that MERCRONÂ’s Sodium Lamp Controller must be used to operate this particular light-source.