Generalized Electrical Substitution Methods and Detectors for Absolute Optical Power Measurements

Area of Science:

• Metrology
• Optical Physics
• Materials Science

Background:

• Electrical substitution radiometers (ESRs) are primary standards for optical power calibration.
• Traditional cryogenic ESRs have slow response times and are difficult to operate, limiting their direct use.
• Accurate calibration of spectral and dynamic optical power is crucial for various scientific applications.

Purpose of the Study:

• To develop generalized methods for electrical substitution optical measurements.
• To create fast-response cryogenic detectors for implementing these methods.
• To enhance the accuracy and efficiency of optical power calibrations.

Main Methods:

• Developed generalized electrical substitution methods for measuring arbitrary periodic waveforms.
• Engineered fast-response cryogenic bolometers with carbon nanotube absorbers using microfabrication.
• Integrated new detectors with generalized electrical substitution for optical calibrations.

Main Results:

• Achieved detector response uncertainty of 0.13% (k=1) and total measurement uncertainty of 1.1% (k=1) in mid-infrared spectral detector responsivity calibrations.
• Demonstrated response times near 10 ms for the new cryogenic detectors.
• Verified the capability of the generalized method for absolute calibration of spectral and dynamic optical power.

Conclusions:

• The generalized electrical substitution method combined with fast cryogenic detectors significantly expands the scope of primary standard optical power calibrations.
• These advancements can shorten calibration chains and improve measurement uncertainties.
• The developed detectors are manufacturable and suitable for a wide spectral range (UV to far-infrared).