Light Sensor Considerations
Specifying the Source and Sensor
Using the LI-6400
8-3
There is a third type of light sensor that is used in the LI-6400. It is a silicon
diode that monitors and controls the optional 6400-02 or -02B LED Light
Source. The silicon diode light sensor has a wide response that covers the red
and blue LED emission range. It is also an unfiltered sensor, but calibration
is simplified because it only views radiation from the LED light source. A cal-
ibration coefficient is provided with each 6400-02 or -02B LED Light Source.
Specifying the Source and Sensor
One of the configuration parameters of OPEN involves specifying the light
source (and indirectly, the sensor). There are reasons this information needs
to be known
¥
LED Light Source Control
Is a light source installed? The answer to this question determines whether or
not the lamp control key in New Measurements mode is active. It also tells
the software what type of in-chamber light sensor is connected.
¥
Calibration Issues
Whatever the type of light sensor being used, it has a calibration factor which
converts raw mV to µmol m
-2
s
-1
photon flux. This conversion factor depends
on the spectral characteristics of the incident radiation. The software can ad-
just this factor depending on what the light source is.
¥
Energy Balance Issues
When leaf temperature is not directly measured, it is computed using a leaf
energy balance (described in Chapter 17). One of the inputs of this computa-
tion is the absorbed radiant energy by the leaf, and this again depends on the
spectral characteristics of the incident radiation.
Calibration Equations
The equations that OPEN uses for computing the readings of its light sensors
are (14-14) through (14-16), starting on page 14-8.
Summary of Contents for LI-6400
Page 1: ...Using the LI 6400 Portable Photosynthesis System ...
Page 15: ...Part I The Basics ...
Page 16: ......
Page 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Page 175: ...Part II Useful Details ...
Page 176: ......
Page 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Page 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Page 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Page 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Page 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Page 289: ...Part III Working With Files ...
Page 290: ......
Page 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Page 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Page 375: ...Part IV Configuration Issues ...
Page 376: ......
Page 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Page 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Page 455: ...Part V Maintenance Troubleshooting ...
Page 456: ......
Page 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Page 593: ...Part VI Programming ...
Page 594: ......
Page 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Page 846: ...Index I 16 Using the LI 6400 ...