Taking Measurements

This section describes precautions, techniques, and processes for taking measurements with the LI-600.

Measurement precautions and techniques

Observe these precautions and practice these techniques before and while taking measurements with the LI-600.

Precautions

To protect the LI-600 when not in use, turn it off and place it in the carrying case. Before using the LI-600, take the following precautions.

  • Charge the battery. A fully charged battery provides approximately 8 hours of active use. See Charging considerations for charging time.
  • Attach and use the wrist strap. To protect the LI-600, attach the wrist strap to the instrument and adjust it to your wrist size. Use the wrist strap at all times (or risk being "the person who dropped it").
  • Insert the USB port protector. To protect the USB port from debris, keep the protector inserted when the instrument is not connected to a computer.

Techniques

The LI-600 can measure the top or the bottom of a leaf. The following techniques help ensure the quality and accuracy of your measurements.

  • Maintain the original orientation of the leaf. Do not alter the angle or positioning of the leaf you are measuring.
  • Maintain the light conditions of the leaf. Do not alter the light on or shade the leaf you are measuring. If, while taking a measurement, you shade the leaf you plan to measure next, unshade the leaf and wait 60 seconds before measuring it.
  • Match the quantum sensor's light conditions to those of the leaf. If the leaf you measure is in the light, ensure that the quantum sensor is also in the light. If the leaf you measure is in shade, ensure that the quantum sensor is also in the shade.
  • Avoid measuring a leaf with water on it. If the leaf you plan to measure has water or condensation on it, gently and thoroughly dry the top and bottom of the leaf.
  • Avoid clamping onto the veins of the leaf. The uneven surface may prevent the aperture clamp from properly sealing. If in auto-mode, the instrument may not take the measurement. If in manual mode, the logged measurement may be inaccurate.
  • Fully fill the aperture with the leaf. To get reliable stomatal conductance readings, the chamber must be completely covered and sealed. When using an LI-600 equipped with a fluorometer, fluorescence readings can be taken without filling the aperture.
  • Maintain unblocked vents on the instrument. Do not cover any of the vents on the instrument when taking measurements.
  • Turn GPS off when not in use. Turning off GPS will save battery power, especially in buildings with poor satellite fix.

Caution: Do not apply pressure to the aperture clamp to achieve a seal on the leaf. This can warp the aperture clamp, interfere with the instrument’s optics, and produce measurement errors.

Taking a measurement

The workflow for taking a measurement on the LI-600 will vary depending on two settings in the active configuration: whether the measurements are taken in Auto mode or Manual mode, and whether Prompt on log is enabled for optional data labels.

Taking a measurement in Auto Mode

In Auto Mode, the LI-600 automatically logs a measurement when the stability criteria set in the configuration are met.

To take a measurement in Auto Mode:

  1. Power on the LI-600.
  2. Select a configuration with Auto mode enabled and press Enter. The instrument will match and go to the Measurement screen. If Prompt on log is not enabled and you want to add data labels or scan a barcode, press the right arrow (Prompt) to Data labels (Press enter to edit highlighted values). Select a data label, press the Enter button, and choose from the options. If you've enabled the barcode scanner with a data label, follow the steps below for using the barcode scanner. Select Done and press Enter to go back to the Measurement screen.
  3. At the prompt Clamp on leaf, open the aperture with the aperture clamp and close it onto the leaf. The instrument will Search for stability, and automatically log the measurement and beep when the stability criteria are met. The Log button is disabled in Auto Mode.
  4. Unclamp the leaf. If Prompt on log is enabled, the data labels screen will appear. Follow the instructions for data labels in Step 2.
  5. Add remark: after a measurement is taken, you can add an optional remark to the measurement by pressing the right arrow key (Mark). Remarks are set in the computer software when editing or creating a configuration.
  6. Press Enter to start a new measurement. Press the left arrow key (Home) to go back to the Select Configuration screen.

Taking a measurement in Manual Mode

In Manual Mode, the instrument does not search for stability or automatically log a measurement.

To take a measurement in manual mode:

  1. Power on the LI-600.
  2. Select a Configuration set to Manual mode. Press Enter. The instrument will match and go to the Measurement screen. If Prompt on Log is disabled: Press the right arrow (Prompt) to add optional data labels and scan a barcode. Select Done and press the Enter button to return to the measurement screen. (See Step 2 in "Taking a measurement in Auto Mode.")
  3. Clamp to leaf: Watch for stability in the gsw and F variables.
  4. Press the Enter buttonto log the measurement when your stability criteria are met.
  5. Unclamp the leaf. If Prompt on log is enabled, the Data labels screen will appear. See step 2 in "Taking a measurement in Auto mode."
  6. Add remark (optional): press the right arrow (Mark) to add a remark. Select the remark and press the Enter button. You will go back to the Measurement screen.
  7. Repeat from step 3 for subsequent measurements, or press the left arrow (Home) to go back to the Select Configuration screen.

When you're done taking measurements, go back to the Select Configuration screen, press the left arrow to Settings. Select Shut down and press the Enter button to safely turn off the instrument.

Using the barcode scanner

To enable the barcode scanner for a configuration, see Data Labels.

You will scan a barcode either before or after a measurement is logged, depending on whether Prompt on log is enabled in the configuration (see Data Labels). If it is enabled, you can scan a barcode after each measurement. If it is not enabled, you can scan the barcode before a measurement by pressing the right arrow (Prompt) from the Measurement screen, and then selecting the barcode label. If you scan the barcode before a measurement, that barcode will apply to subsequent measurements until you scan another barcode.

To scan a barcode:

  1. At the Data labels screen, navigate to the barcode label and press the Enter button. The barcode prompt will appear.
  2. At the Scan Barcode prompt, pass the red light from the barcode scanner on the bottom of the instrument over the barcode. When it reads the barcode the LI-600 will beep and return to the Measurement screen.

The barcode scanner will time out after a few seconds. If this happens, go back to Data labels and repeat the process.

Viewing measurement data on-screen

Data from the most recent measurement appear on the Measurement screen after taking a measurement, and before pressing the Enter button for a new measurement. For information on configuring the variables shown on the Measurement screen, see Display Layout.