Vaisala CARBOCAP GMP231, User Manual, Page: 15 / 92

1 2
3 4
5
6
7 8
9 10
Figure 4 CO
2
measurement inside the incubator
1 Chamber wall
2 Chamber interior
3 Light source
4 Band pass filter
5 Ambient air (400 … 1000 ppm CO
2
)
6 Light absorbed by CO
2
in the incubator gas
7 Thermopile detector
8 Fabry-Perot interferometer
9 Sapphire window. Separates the sensor’s active components from the
measured environment.
10 Gold-plated mirror
2.5 Environmental compensation
GMP231 improves the CO
2
measurement accuracy by applying various environmental
compensations. GMP231 compensates for the effects of:
• Pressure
• Temperature
• Background gas oxygen (O
2
) content
• Background gas relative humidity (%RH)
Compensation parameters are configured on the order form when ordering the probe, and can
later be updated using serial commands, MI70 Indicator, or I
2
C protocol. If the probe is
integrated in a system that measures one or more of the compensation parameters, they can
be updated to the probe continuously.
Chapter 2 – Product overview
13