Measuring Principle - Konica Minolta JM-103 Instruction Manual

Measuring Principle

The Jaundice Meter JM-103 determines the yellowness of the subcuta-
neous tissue of a newborn infant by measuring the difference in optical
densities for light in the blue (450 nm) and green (550 nm) wavelength
regions. The measuring probe has two optical paths (see Fig. 1). The
use of this method allows measurement of yellowness of the skin and
subcutaneous of a newborn infant with the influences of melanin pig-
ment and skin maturity kept at a minimum, which was impossible with
conventional methods.
2-wavelength
photodiode
Long optical path
Light-emitting path
Short optical path
When the measuring probe is pressed against the forehead or sternum
of the infant, the built-in xenon lamp flashes, and the light from the xenon
lamp is guided to the skin surface through the glass fiber and illuminates
the skin. The light is then scattered and absorbed in the skin repeat-
edly, and finally returns to the glass fiber (sensor side). Of the light
that returns to the fiber, the part scattered from shallow areas of the
subcutaneous tissue passes through the inner core (short optical path)
of the fiber while the part scattered from deep areas of the subcutaneous
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2-wavelength
photodiode
Diffuser panel
Sensor for long
optical path
Diffuser panel
Sensor for short
optical path
Glass fiber
Fig. 1
Xenon lamp