OLYMPIC BILI-METER
Instruction Manual
3
Measuring Irradiance
The Bili-Meter is a spectroradiometer that measures the therapeutic irradiance
(radiant power) of neonatal phototherapy lights. It measures the irradiance of the
wavelengths from 425 to 475 nanometers (nm), the blue-green portion of the
spectrum, which includes the principal action spectrum of bilirubin.
Units of Measurement
The Bili-Meter measures irradiance in units of microwatts per square centimeter
per nanometer (µW/cm
2
/nm). A nanometer is a measure of wavelength equal to
one-billionth of a centimeter. The term “per nanometer” indicates the average
irradiance per nanometer across the spectral band being measured, which is 50 nm
wide. This makes it possible to compare average irradiance across spectral bands of
different widths.
Instrument Response Characteristics
Figure 4 represents the nominal response characteristics of the Bili-Meter, which
matches the action spectrum of bilirubin as closely as possible.
Figure 4
Nominal response of the Bili-Meter
Action spectrum of bilirubin
425–475 nm
400
450
500
