A secondary standard refers to a stable light source that is calibrated either directly or indirectly by comparison with a primary standard. The primary standard is a recognized and well-defined light source that serves as the ultimate reference point for calibration. The secondary standard, in contrast, is calibrated based on its relationship with the primary standard.
Purpose and Importance
Secondary standards are crucial in the field of lighting technology as they provide a reliable benchmark for accurate calibration and measurement. These standards enable professionals to ensure consistency and uniformity in lighting systems, which is essential for effective lighting design, energy efficiency, and visual comfort.
Due to the inherent limitations of primary standards (such as availability and practicality), secondary standards are employed to extend the reference point for calibration. This allows for broader access, wider application, and convenient comparability to the primary standard.
Types of Secondary Standards
Secondary standards can take various forms depending on their specific application and calibration method. Some common types include:
1. Transfer Standards: These secondary standards are calibrated using a direct comparison with a primary standard. The transfer process involves carefully matching characteristics such as spectral power distribution, color temperature, and luminous flux.
2. Working Standards: Working standards are secondary sources that are periodically recalibrated against the primary standard to maintain their accuracy. These standards are typically used in laboratory settings and require regular verification.
3. Reference Standards: Reference standards are secondary sources that serve as a reference point within a specific range of applications. They are often designed to mimic the characteristics of the primary standard and are regularly revalidated against it.
In summary, a secondary standard in lighting technology is a stable light source calibrated directly or indirectly by comparison with a primary standard. It serves as a reliable benchmark for calibration and ensures consistency and uniformity in lighting systems. By extending the reference point provided by primary standards, secondary standards play a crucial role in maintaining accurate and reliable lighting measurements. Proper understanding and utilization of secondary standards contribute to effective lighting design, energy efficiency, and improved visual comfort.