Ageing of s-10 photocathodes

Area of Science:

• Photodetector technology
• Optical metrology

Background:

• Vacuum photodiodes with S-10 (Ag-Bi-O-Cs) photocathodes are widely used in optical measurements.
• Understanding photocathode stability is crucial for accurate and reproducible results.

Purpose of the Study:

• To investigate the long-term spectral sensitivity stability of S-10 photocathodes.
• To quantify changes in spectral sensitivity over a 3-year period.
• To assess the implications of these changes on photometric and colorimetric measurements.

Main Methods:

• Repeated measurements of relative spectral sensitivity distributions.
• Monitoring ten vacuum photodiodes equipped with S-10 photocathodes.
• Data analysis over a duration of up to 3 years.

Main Results:

• Significant changes in spectral sensitivity distributions were observed in S-10 photocathodes within the first three years of their operational life.
• The rate and extent of these changes varied among individual photocathodes.
• The observed spectral variations can lead to inaccuracies in photometric and colorimetric data.

Conclusions:

• S-10 photocathode spectral sensitivity is not stable over the initial three years.
• These temporal changes necessitate recalibration or correction factors for precise photometric and colorimetric applications.
• Further research into the mechanisms of photocathode degradation may improve device longevity and measurement accuracy.