Application Notes


Frequently Asked Questions

A PAR sensor and quantum sensor both measure photosynthetically active radiation (PAR). These terms are both used for sensors that measure light in the 400-700 nm waveband. The terms are interchangeable.

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.

You can connect up to three LI-COR light sensors, using the three BNC bulkhead connectors.

One sensor can be connected to the LI-250A light meter at a time but up to two multipliers can be saved.

The "BNC" sensors terminate with BNC connectors and are most commonly used with the LI-1500 datalogger or LI-250A light meter. The BL sensors have bare leads that deliver a microamp current output. The SMV sensors are connected to a Standard Millivolt Adapter and have bare leads with a variable resister with a standardized 10 mV output at full scale.

No. LI-COR sensors are based on a photodiode, which generates its own current. Power must be provided to the data reader, however.

The quantum sensors (LI-190R and LI-191R) measure light in the photosynthetically active radiation waveband. These sensors should be used to determine how much PAR a set of plants or canopy is receiving.

The LI-210R photometric sensor measures light as perceived by the average human eye. It should be used in any application that relies on human perceptions of light such as smart buildings or external lighting arrays.

The LI-200R pyranometer measures solar radiation from 400 to 1100 nm and will give you a good idea of how much sun your building receives.

Yes, we recommend that all our light sensors be recalibrated every two years. Recalibration can be done year-round for all sensors except the LI-200R. The LI-200R can only be calibrated between March 1 and September 30 each year.

This will depend on your data logger. If a microamp BNC connection is available, you can order the BNC termination option to provide this. If a two-wire connection is required, then use either the BL bare wire termination, SMV Standard Millivolt Adapter, or a millivolt adapter.

For the BL sensors, the brown wire is negative, the blue wire is positive, and the bare wire can be connected to ground to reduce signal noise. For the millivolt adapter, the green lead is positive and the blue lead is negative.

The provided wiring instructions are for use with the standard negative multiplier of the sensor. If you reverse the wiring, simply reverse the sign of the multiplier.

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

Yes, you probably can. Please call our support staff at 1-800-447-3576 and they will be happy to discuss connection options with you.