Referenzlampen

Referenzlampen are specialised light sources that serve as stable, well‑characterised references for optical measurements, calibration, and quality control in scientific, industrial and consumer applications. Their principal purpose is to provide a reproducible spectral output that can be compared against unknown samples or measurement instruments, thereby enabling accurate determination of quantities such as irradiance, spectral power distribution, colour temperature or photometric performance.

The use of reference lamps dates back to the early 20th century, when the introduction of incandescent and later halogen sources allowed for the first calibrated photometric measurements. Over time the technology evolved, driving the development of spectrally flat quartz‑tungsten halogen lamps, stabilized xenon arc lamps, and, more recently, high‑pressure sodium lamps and LED‑based references. Modern devices are manufactured to stringent tolerances and are often characterised by national metrology institutes, with traceability to national and international standards such as ISO 17025.

Typical applications include spectrophotometer calibration, colour measurement in printing and manufacturing, illumination level control in photographic studios, and the calibration of dosimetric equipment for dental or medical imaging. In spectroscopy, a reference lamp provides a baseline spectrum against which sample spectra are compared to remove instrument response. In lighting design, a reference lamp assists in verifying the colour rendering index (CRI) of new fixtures against a known standard.

Reference lamps are classified by their emission characteristics, stability, and maintenance requirements. Tungsten‑halogen lamps offer a continuous spectrum but require frequent filament replacement, whereas high‑pressure sodium lamps deliver a narrow spectral feature useful for absolute wavelength calibration. LED‑based references are increasingly used in compact, low‑power systems owing to their long lifetime and minimal visual heat emission.

Standardised reference lamps are listed in national inventories and are essential for maintaining measurement consistency across laboratories and industries. Their continued development remains a focus of photometry, metrology and optical engineering communities worldwide.