Patent ID: 9549695
Date: 2017-01-24
CPC Classifications: A61B

Claim:
1. A method for measuring at least one physiological parameter of tissue by means of a semiconductor light source and of a light detector, wherein said parameter affects concentration of blood constituents, in particular different forms of hemoglobin, said method comprising the steps of a) placing said light source and said light detector such that said light detector measures an amount of light transmitted from said light source through said tissue, b) operating said light source under a first condition where it has a first temperature, and determining a first light attenuation signal by means of said light detector, c) operating said light source under a second condition where it has a second temperature different from the first temperature, and determining a second light attenuation signal by means of said light detector, d) determining said parameter using said first light attenuation signal and said second light attenuation signal, wherein said method further comprises the step of varying a current through said light source in order to create said different operating conditions by switching said current from a first level to a second, different level and determining at least part of said attenuation signals at different times after switching said current while said light source has not yet reached thermal equilibrium.