Spectron Engineering SE590 - Radiance Calibration

Introduction

Measurements from an SE590 are reported in counts for each channel.  If the intended results from a research question is reflectance factors and the same instrument is used to measure the reflected and incoming radiant energy components the units of counts would be acceptable.  However, if different instruments are used or the research question is to find the actual amount of energy that is being measured, the SE590 must be calibrated and data converted to units such as Watts per square meter per nanometer (per steradian).

To accomplish this calibration, data is collected from a light source with a known energy output. A brief description  of the calibration procedure and the current calibration follows:

• Radiance Calibration - The SE590 with a 15^o FOV lens measures the light in an integrating sphere with four xxxx lamps.  The factory energy output  values for the lamp are divided by the counts for each channel to develop conversion coefficients with units of Watts per square meter per nanometer per sterradian per count.
• Irradiance Calibration - The SE590 with hemispherical lens measures a Oriel  Corporation Model 63355 lamp.  The factory energy output values are divided by counts for each channel to develop a conversion coefficient with units of Watts per square meter per nanometer per count.

Current Conversion Coefficients for Radiance and Irradiance

Calibration conducted on February 20, 1998 and wavelengths are from the characterization on February 23, 1998.