General Information

This manual provides basic operating instructions for the LI-200R Pyranometer and its accessories. The LI-200R measures global solar radiation (solar irradiance received on a horizontal surface) with a silicon photodiode mounted under a cosine-corrected acrylic diffuser. The sensor output is a current (μA) signal that is directly proportional to hemispherical solar radiation. A multiplier is used to convert the current signal into units of radiation (W m-2).

Typical applications for the LI-200R include solar energy, meteorology, agriculture, and environmental research.

Important Note: The LI-200R should only be used to measure unobstructed daylight. Measurements under vegetation, cloud cover, artificial lights, in a greenhouse, or of reflected solar radiation may not be accurate. The spectral response of the LI-200R does not include the entire solar spectrum (Figure 5‑3). Therefore, it must be used under lighting conditions that are the same as those under which it was calibrated.

Comparing LI-COR Radiation Sensors

Each LI-COR radiation sensor is optimized for a particular application and measurement type (Table 1‑1). LI-192SA and LI-193SA sensors are submersible, but they can also be used in the atmosphere. The LI-191R Line Quantum Sensor is often used within plant canopies. LI-190R, LI-200R, and LI-210R sensors consist of a sensor head attached to a removable base and cable assembly.

Table 1‑1. LI-COR radiation sensors.
Sensor Measurement Units Waveband
LI-190R Quantum Sensor Photosynthetically active radiation (PAR) μmol s‑1 m‑2 400 to 700 nm
LI-191R Line Quantum Sensor
LI-192SA Underwater Quantum Sensor
LI-193SA Underwater Spherical Quantum Sensor
LI-200R Pyranometer Global solar radiation W m‑2 400 to 1100 nm
LI-210R Photometric Sensor Light as perceived by the human eye Lux or klux 450 to 650 nm
Figure 1‑1. LI-COR radiation sensors.

Cable Options

The detachable base and cable assembly provides benefits including:

  • Reduced cost of cable repairs
  • The ability to replace or recalibrate a light sensor without removing the cable from the mounting structure
  • Cable interchangeability with any LI-190R, LI-200R, or LI-210R sensor head
Figure 1‑2. Sensor base and cable assembly detached from the sensor head.

The shielded cable leading from the sensor base terminates with either bare wire leads or a weather-resistant, nickel-plated brass BNC connector (Figure 1‑3). For sensors with a BNC connector, the body of the connector carries a positive signal and is connected to the shield of the cable, while the center conductor is negative. This arrangement reduces electronic interference.

Figure 1‑3. Sensor terminals are either a BNC connector or bare leads.

BNC or bare leads (BL) terminal types are available with cable lengths of 2, 5, 15, or 50 meters.

Calibrated LI-190R, LI-200R, or LI-210R sensor heads (without cables) are available for purchase. Sensor heads can replace damaged heads, or be used as spares. Any cable assembly can be used interchangeably with any LI-190R, LI-200R, or LI-210R sensor head.

Accessories

These optional accessories are available for use with the LI-200R Pyranometer:

  • 2220 Millivolt Adapter, 147 Ω resistance (2220 Millivolt Adapter)
  • 2420 Light Sensor Amplifier (2420 Light Sensor Amplifier)
  • 2003S Mounting and Leveling Fixture. Anodized aluminum with stainless steel leveling screws and a weatherproof spirit level
  • 2001S Sensor Base Cover. Anodized aluminum

Configurations

The LI-200R Pyranometer connects directly to devices that read a current (µA) sensor signal (Table 1‑2). Table 1‑3 lists pyranometer configurations for producing a voltage signal.

Table 1‑2. Configurations for a current (µA) signal. Ultimate termination is BNC or bare leads.
Sensor Termination Type... ...connects to...
LI-200R-BNC
  • LI-1500 Light Sensor Logger
  • LI‑1400 Datalogger
  • LI-250A Light Meter
LI-200R-BL
  • Terminal block of the LI‑1400 Datalogger
  • Non-LI-COR devices that read a current (μA) signal
Table 1‑3. Configurations for a voltage signal. Ultimate termination is bare leads.
Sensor Termination... ...coupled with... ...connects to...
LI-200R-BNC 2220 mV Adapter
(0 to 10 mV output)		 Devices that read a voltage signal with good resolution (in the µV range)
LI-200R-SMV Includes a standard output mV adapter with 10 mV output at full scale (part number 2320)
LI-200R-BL Precision resistor
LI-200R-BNC 2420-BNC Amplifier
(-2.5 to 5.0 V output)
 Devices that read a voltage signal
LI-200R-BL 2420-BL Amplifier
(-2.5 to 5.0 V output)