Ocean Optics RaySphere 1700 Install - Manual (Page 56)

9: Nonlinearity Correction, Stray Light Correction and Calibration
46 RAYSPHERE-1700-02-201304
Sources of Uncertainty
The following parameters have influence on the uncertainty of calibration. Each parameter is taken into
account when calculating for uncertainty.
Quantity Source of Uncertainty
1. I_DC Uncertainty of DC current
2.1 T and F Influence of temperature [T] and humidity in air [F] for wavelength
range 300 nm to 1100 nm
2.2 T and F Influence of temperature [T] and humidity in air [F] for wavelength
range 1100 nm to 1700 nm
3.1 d Misalignment: Horizontal distance [d] from calibrated light source to
entrance plane of aperture
3.2 alpha Misalignment: Tilting of the RaySphere to the light source
4. Dark Noise of dark-level [dark]
5. T_TEC Influence of sensor temperature [T_TEC]
6. Irr_Kal Uncertainty of calibration lamp
7. D_Lambda Uncertainty of wavelength calibration
8. StrayL Influence of spectrometer’s internal stray light
Uncertainty of DC Current
The lamp manufacturer has defined the current for operating the calibration lamp. The current is
monitored during calibration of RaySphere with calibrated equipment. The measurement has an
uncertainty which is given the in the device’s calibration documents of the power supply.
Influence of Temperature and Humidity
The ambient temperature during the calibration procedure may influence the uncertainty of the
calibration. It is recommended by NIST to monitor temperature and humidity. The influence of humidity
can be neglected for a wavelength range of 300 to 1100 nm since the atmosphere components do not a
significant influence on the result. For a higher wavelength, there is a significant influence on the
accuracy since water in the air has several absorption bands. The correlation of humidity and absorbance
is not taken into account for calculations of uncertainty.