Bandpass Filter: Center Wavelength Shift due to Temperature Changes
Interactive Playground
You can play around to see the temperature impact on bandpass ftiler with below interactive session:
https://syronoptics.github.io/WavelengthTemperatureShift/
Wavelength Shift
The center wavelength experiences a linear shift with temperature changes:
- Most filters show a red shift (shift to longer wavelengths) with increasing temperature
- The shift typically ranges between 2-5 picometers per °C in standard operating conditions
- Some specialized filters may exhibit a blue shift depending on their construction materials
Physical Changes
Temperature increase affects the filter's structure through:
- Expansion or contraction of thin-film layers
- Changes in the optical thickness of multilayer components
- Potential stress in the coating materials
Performance Limitations
Temperature effects have practical implications:
- Changes are fully reversible for temperatures below 125°C
- Maximum recommended operating temperature is typically 70°C
- Rapid temperature changes should be limited to 5°C per minute to prevent thermal shock
Critical Considerations
For optimal performance:
- Filters should be specified for their intended operating temperature
- Environmental stability becomes crucial when high humidity and temperature variations occur simultaneously
- Different material sets and deposition methods can lead to varying rates of temperature-induced changes
