Photometer Operating and Calibration Guide
Photometers measure light intensity, luminance, and related optical properties. They are used in display testing, lighting design, and material analysis.
I. Operating Principles
- Illuminance Measurement: Measures light falling on a surface, expressed in lux
- Luminance Measurement: Measures light emitted or reflected from a surface, expressed in candela per square meter
- Luminous Intensity: Measures light output from a source in a specific direction, expressed in candela
- Luminous Flux: Measures total light output from a source, measured using an integrating sphere
II. Operating Procedures
- Allow the photometer to warm up for the specified time before measurements
- Perform dark current measurement by covering the sensor to establish the zero reference
- Calibrate with a known light source or reference standard before measurements
- Take multiple readings and average for improved accuracy
- Record environmental conditions (temperature, humidity) as they may affect readings
III. Calibration
- Use a calibrated reference lamp with known luminous intensity or luminous flux
- Verify the photometer's spectral response matches the CIE photopic luminosity function
- Calibrate annually or per quality system requirements
- Maintain calibration chain traceability to national standards
IV. Maintenance
- Keep optical surfaces clean using appropriate cleaning materials
- Protect the detector from overload by using appropriate attenuation
- Store in a dust-free environment with desiccant
- Replace aging reference lamps on schedule
