Leaf Area Meter, LI-3100C

Protocol

Author

Louis Santiago

Modified from: LI-3100C Area Meter, Instruction Manual, Publication No. 984-07704, LI-COR, Inc., 2004

Overview

Using a LI-COR 3100C to obtain leaf area measurements (in cm2).

Materials/Equipment

  • LI-3100C (leaf area meter)
  • Transparent Belts
  • Fluorescent Tubes (light bulbs)
  • Camera
  • 2- 10 cm2 Calibration Discs (1 round, 1 rectangular & perforated)
  • Spare 1 Amp and 1/2 Amp Time Delay fuses
  • 5/32″ (4mm) hexagonal key
  • RS-232 cable (for use with a computer)

Procedure

  1. Preparation for First Use
    a. Install the Fluorescent Tube (step 2).
    b. Adjust Transparent Belt Tension (step 3).
    c. Install Camera (step 4).
    d. Check Voltage Selector (step 5).
  2. Install Fluorescent Tube
    a. Remove rear housing by using 5/32″ (4mm) hexagonal key to remove the 4 retaining screws. Lift the housing from the instrument.
    b. Remove the rear tube connector housing by loosening the 2 recessed mounting screws
    c. Hold new tube vertically and gently tap it. This will cause any internal debris to collect at one end. Internal debris can create errors in the area calculations.
    d. Slide tube into exposed hole in the instrument rear plate. Rotate the tube as necessary until it seats in the front connector. Twist the tube (any either direction) slightly until it snaps into place.
    e. Mount the rear connector housing over the exposed tube end.
    f. Gently twist the connector while holding the tube at the back edge of the upper belt. The rotation should be about ¼ turn.
    g. Replace rear housing.
  3. Adjust Transparent Belt Tension
    a. Remove rear housing by using 5/32″ (4mm) hexagonal key to remove the 4 retaining screws. Lift the housing from the instrument.
    b. Loosen the large knobs located on each sliding pulley bearing block.
    c. Coarse adjustment is performed by simultaneously sliding both bearing blocks for one pulley. The knobs can be tightened sufficiently by rotating them with the thumb and index finger while holding tension on the bearing block with the remaining fingers of the same hand.
    d. Fine adjustments are performed by twisting the block adjustment screw to push the sliding bearing block. The knobs located on the pulley must be loosened to allow block movement.
    e. Replace rear housing
  4. Install Camera
    Loosen the outer camera pressure rail screws. Do not remove the black light shield tape adjoining the circuit board. Install the lens at the location appropriate to the resolution desired.
  5. Check Voltage Selector
    The voltage selector is located in the power connector module. The selector is inspected for proper voltage by sliding the clear plastic window to a position over the power connector. The visible number on the small printed circuit board located under the fuse indicates the selected voltage. The voltage selector is changed by sliding the circuit board outward from its mount and repositioning it so that a different number is visible as appropriate to the available voltage. If changing the voltage, an instrument calibration should be performed afterwards. If main current frequency fluctuates often, calibration should be checked often.
  6. Calibration
    Calibration is necessary after installing a new lamp (let it run for several hours first) or after replacing extremely worn or cloudy belts or when a large change in ambient temperature occurs or if there is an obvious maladjustment. Using the calibration discs (2 – 10cm2 round, rectangular, and perforated), run them through the leaf area meter in all positions on the transparent belts (front, back, and middle) ten times and average the readings, if the error exceeds 2% carefully turn the CAL screw a small amount, clockwise to increase or counterclockwise to decrease.
  7. Running Samples
    When you are ready to run samples through the leaf area meter, first be sure that the power is on and the transparent belts are clean (if not, wipe them with rubbing alcohol and a Kim wipe). Turn the lamps on by pressing the “Lamp Start” button. Next, put a sample on the transparent belt to the right of the silver bar in front of the display panel and press the “zero” button to obtain an accurate measurement of leaf area in square centimeters on the display panel, let the sample run through and then record leaf area. There is also a silver adjustable pressing roller located to the left of the silver bar in front of the display panel which when a small amount of pressure is applied is used to press curled leaves.
  8. Clean Up
    After all the samples are run through the leaf area meter, turn the lamp off, clean any debris off of the transparent belts, and then power off. Cover the machine with the black protective cover.

LI-3100C Area Meter, Instruction Manual, Publication No. 984-07704, LI-COR, Inc., 2004

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