Illumination Source
A high-intensity light source that emits a brief pulse of light matching the daylight spectrum provides the illumination for modern spectrophotometers. Using a xenon flash lamp in a textile laboratory allows for rapid and precise measurement of fabric color without heating the sample. This technology is standard in both benchtop and portable measuring instruments.
Flash Mechanism
The lamp consists of a sealed glass tube filled with xenon gas, which is excited by a high-voltage electrical discharge. This produces a microsecond pulse of light that covers the full range of visible and ultraviolet wavelengths. Because the flash is so short, it does not heat the fabric fibers, which is crucial for preventing thermal metamerism.
In older instruments with tungsten lamps, the continuous heat could dry out the fabric sample, causing its color to shift temporarily during measurement.
Dyehouse Maintenance
Operating life for such components is long, often exceeding millions of flashes before requiring replacement. However, their ultraviolet output can degrade over time, which requires regular fluorescence adjustments using a calibrated tile to maintain accuracy.
Thermal Boundary
While the short flash avoids heating the sample, the high peak power can still cause temporary photo-chromic shifts in certain sensitive dyes. Technicians must be aware of this behavior when measuring fabrics dyed with highly sensitive yellow or red dyes.
