Frequently asked questions

You can look up the calibration data for most LI-COR instruments by selecting Calibration Certificates above the search bar and entering the serial number. You can also contact us to get the information.

The LI-190R and LI-191R current output typically ranges from 5 to 10 µA/1000 µmol/s/m2. The following table shows the reading you should expect in common lighting conditions.

  Current Units
(µA)		 Voltage Units
(mV)		 Photon Units
(µmol/s/m2)
Indoor/Office light 0.00 - (0.15 - 0.3) 0 - 0.15 0 - 30
Cloudy Day 0 - (2.5 - 5) 0 - 2.5 0 - 500??
Full Sun 10 - 20 10 2000

Light sensor factory calibration procedures are described in detail here.

Unreasonable readings can occur for a variety of reasons. With the LI-1500, readings of 0 are caused by reversed polarity of the cable or an incorrect calibration multiplier. With the LI-250A and LI-1400, readings with a negative value are caused by reversed polarity of the cable or an incorrect calibration multiplier. These are described in troubleshooting.

Light sensors output a voltage or current signal, which can be read by the LI-250A, LI-1500, or many dataloggers.

The following topics describe how to connect the sensor:

To fix a dataset, simply divide by the incorrect multiplier and multiply by the correct multiplier.

0 to 25 mV, or 16-bit 0 to 100 mV.

The light sensor amplifier can rescale the sensor output for different datalogger inputs.

The LI-191R gives you the integrated PAR over the 1-meter length. This is ideal for measuring light interceptance by a plant canopy. Under canopies, there are areas that are completely sunlit, completely shaded, and areas that have some transmission of partial light through the leaves. The LI-191R gives an average PAR over all these conditions. The LI-190R measures light at a single point.

Cleaning instructions are provided here.
You can connect LI-COR light sensors to a voltage logger, as described here.
Sensors that are deployed in their measurement environment are recommended to be calibrated every two years. However, if stored properly, the time-to-calibration could potentially be extended.
The only way to verify the performance is to have it recalibrated at LI-COR. But if only some rough estimate is needed, you can find another new or recent calibrated sensor and do some side-by-side comparisons.

This question is most often asked to determine whether the measurements being obtained are reliable and correct. In this case, one generally wants to know the “full-scale” response of their sensor, or what would be seen under the most ideal conditions. However, LI-COR light sensors can measure values far above the full-scale response, so the maximum value that can be obtained may not be a correct value to use when determining whether the measurements are reliable and correct.

The LI-190/R, LI-191/R, LI-192, and LI-193 are all quantum sensors. All of our quantum sensors have a linear response up to 10,000 μmol m-2 s-1, but the full-scale value on a clear sunny day is approximately 2000 μmol m-2 s-1. Again, spikes due to cloud-edge effects can be higher, but these readings should be transient.

If you have any questions about accuracy of LI-COR light sensors, please contact us for assistance.

No. Some companies incorporate LI-COR pyranometers in their sun tracker devices, but LI-COR no longer makes one.