Solar Physics

, Volume 230, Issue 1–2, pp 91–109 | Cite as

The Total Irradiance Monitor (TIM): Instrument Design

  • Greg KoppEmail author
  • George Lawrence


The Total Irradiance Monitor (TIM) instrument is designed to measure total solar irradiance with an absolute accuracy of 100 parts per million. Four electrical substitution radiometers behind precision apertures measure input radiant power while providing redundancy. Duty cycling the use of the radiometers tracks degradation of the nickel-phosphorous absorptive black radiometer interiors caused by solar exposure. Phase sensitive detection at the shutter frequency reduces noise and simplifies the estimate of the radiometer's equivalence ratio. An as-designed uncertainty budget estimates the instrument's accuracy goal. The TIM measurement equation defines the conversion from measured signal to solar irradiance.


Measured Signal Radiant Power Equivalence Ratio Solar Irradiance Measurement Equation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science + Business Media, Inc. 2005

Authors and Affiliations

  1. 1.Laboratory for Atmospheric and Space PhysicsUniversity of ColoradoBoulder

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