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4. Light Sources

4. Light Sources

Owned by Wilhelm Scheermann
Jan 30, 2023
2 min read

A variety of illumination sources are available for use in machine vision applications: fluorescent, quartz halogen, metal halide, xenon, OLEDs and LEDs.

Each light source has different characteristics in spectral distribution, radiation output, response speed, lifetime, heat generation, and degree of design freedom for different inspection requirements. Table 1 summarizes their properties.

Light Source

Benefits

Limitations

Light Source

Benefits

Limitations

LED

Long service life (30,000 to 100,000 hours)
Low power consumption, heat generation
Stable output
Flexible design (wavelength, form factor) and operation (continuous and strobing)
High shock and vibration resistance

 

Risk of LED deterioration and decrease in brightness caused by heat
White LEDs appear blue
Single color source can make features hard to see
Higher short-term cost

OLED

Thin housing (3mm)
Long service life (20,00p to 50,000 hours)
Low heat generation
High uniformity
Continuous and strobing
Flexible design in color and shape

Primarily backlighting applications
New technology still in-development
Limited wavelengths (white and red)

Fluorescent Lamps

Suitable for illuminating large areas

Strong heat generation
Short service life (several thousand hours) with significant loss of brightness after several months
Emission peaks in specific wavelength ranges
Limited design (rod shape, color possible but rare)
Continuous only (no strobing)
White fluorescent lights appear green, shifts to blue over time

Quartz Halogen Lamps

Suitable for illuminating large areas
Suitable for microscopy
High infrared emission
Continuous and strobing (but long switching times)

Strong heat generation
Short service life (1,000 to several thousand hours)
High power consumption
Limited design (mainly spotlight, no color)
Highly sensitive to vibration
White halogen lights appear yellow, shifts to red over time
Potential environmental risks

Metal Halide Lamps

Suitable for illuminating large areas
Suitable for microscopy

Short service life (10,000 hours)
Emission peaks in specific wavelength ranges
Shift in color temperature over time
Long warm-up period

Xenon Lamps

High intensity
Suitable for illuminating large areas
Suitable for microscopy

Strobe only (no continuous)

 

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