Using the LI-210R Photometric Sensor

Mounting

The LI-210R Photometric Sensor may be hand-held or mounted to an instrument platform. For best results, install your sensor in the 2003S Mounting and Leveling Fixture. Secure the sensor in the fixture by tightening the mounting screws against the sensor base. Level the fixture with the bubble by adjusting the three leveling screws. The 2003S Mounting and Leveling Fixture can be secured to a structure with bolts or screws placed through the three holes in the fixture.

Figure 2‑1. LI-210R Photometric Sensor mounted in the 2003S Mounting and Leveling Fixture.

Secure cables to the instrument platform using cable ties. Be sure there is no strain on the junction where the cable enters the sensor housing, and use a cable tie at any sharp bends in the cable.

Calibration Constants and Multipliers

Each LI-COR radiation sensor is shipped with a certificate of calibration. The certificate is also available at www.licor.com/env/support/. Enter the sensor's serial number in the calibration search box. The calibration constant and multipliers are listed on the certificate in the following order:

Calibration constant

The current signal produced by a photometric sensor is related to radiation intensity with a calibration constant unique to each sensor, expressed in units of µA per 100 klux. The calibration constant is used to compute calibration multipliers.

Multiplier for use with LI-COR handheld meters and loggers

LI-COR handheld meters and loggers convert the current (μA) signal into units of radiation (klux) by applying this multiplier, expressed in radiation units per current (klux µA-1). This multiplier is a negative number.

Multiplier for use with LI-210R-BL (3-wire bare leads)

This multiplier is expressed in radiation units per current (klux µA-1) and is a positive number.

Multiplier for use with LI-COR 2290 (604 Ω) Millivolt Adapter

This multiplier is expressed in radiation units per voltage (klux mV-1) and is a negative number.

Multiplier for use with the SMV Photometric Sensor

The final multiplier listed is ‑10.0 klux mV-1. The multiplier is the same for any LI-210R-SMV Photometric Sensor because the resistance of the included standard output millivolt adapter (part number 2321) is adjusted to each sensor's current output (Voltage Signal Options). The LI-210R-SMV replaces the LI-210SL and uses the same millivolt adapter and multiplier.

Using the LI-210R-BNC Photometric Sensor

Connect the BNC-type cable directly to a BNC input port on an LI-250A Light Meter, LI‑1400 Datalogger, or LI-1500 Light Sensor Logger. These devices directly measure the current (μA) signal from the sensor. Enter the sensor's multiplier (see Multiplier for use with LI-COR handheld meters and loggers) into the device to determine visible light expressed in units of klux.

Figure 2‑2. LI-210R-BNC Photometric Sensor.

Using the LI-210R-BL Photometric Sensor

Figure 2‑3. LI-210R-BL Photometric Sensor featuring 3-wire bare leads.

A BL-type sensor cable terminates with bare wire leads. Connect the bare leads to the input terminal block of a device that directly measures a current (μA) signal. The blue wire carries a positive signal and the brown wire is negative. Connecting the bare (shield) wire to ground will reduce noise in the sensor signal.

To log radiation units (klux), configure the recording device to multiply the μA signal by the sensor's multiplier (see Multiplier for use with LI-210R-BL (3-wire bare leads)) prior to logging the values. If logging the μA sensor signal, apply the multiplier after logging.

The LI-210R-BL can be used with recording devices that require a voltage (mV) signal by adding a precision resistor (see Voltage Signal Options).

Voltage Signal Options

If the meter or logging device requires a voltage signal, options include:

  • LI-210R-BNC coupled with a 2290 Millivolt Adapter. The 2290 Millivolt Adapter converts the current (µA) signal from the sensor into a millivolt-level voltage (Multiplier for use with LI-COR 2290 (604 Ω) Millivolt Adapter).
  • LI-210R-SMV Photometric Sensor. The LI-210R-SMV includes a Standardized Millivolt Adapter (part number 2321) matched to a particular sensor. The serial numbers on the adapter and the sensor must match! The advantage over the 2290 Millivolt Adapter is that the multiplier in your device does not need to be changed for different sensors (Millivolt Adapters).
  • LI-210R coupled with a 2420 Light Sensor Amplifier. The 2420 Amplifier converts the current (µA) signal from the sensor into a voltage (2420 Light Sensor Amplifier).
  • LI-210R-BL coupled with a precision resistor. Connect the resistor across the positive and negative leads of the cable. The recommended resistance is 604 Ω, with a maximum output of approximately 10 mV per 100 klux. See Multiplier for use with LI-COR 2290 (604 Ω) Millivolt Adapter for instructions on calculating the multiplier, but use the absolute value of the multiplier.

With a Millivolt Adapter or other resistor, the signal to noise ratio (sensitivity) is lower than with the 2420 Light Sensor Amplifier, but the cost is less and there is no need for a power supply to the adapter.

Caution: Do not attach the sensor to a power source. The sensor is self-powered.