The Standard in

Plant Stress Measurement



Technology leadership - The iFL is a field portable integrated chlorophyll fluorometer - photosynthesis system

The iFL is the first instrument of its kind to provide leaf absorptance measurement, first to offer white LED lighting that allows chloroplast migration to occur, first to offer humidity control above ambient, first to offer "walk-away automation", first to offer automated post-processing for the Laisk protocol, the Kok protocol, the Yin protocol and the Flexas chamber leakage protocol.


  • Leaf absorptance and leaf transmittance are measured
  • Non-contact IR sensor for leaf temperature measurement prevents leaf doming that causes measuring errors
  • FM' correction option included, according to Loriaux 2013
  • Automated instrument zero calibration occurs as programmed
  • Stable light intensity - monitored and controlled for more reliable  measurements
  • Measures CO2 to  +/-1 μmol or +/- 1 ppm
  • Measures H2O to +/- 1 mmol
  • Fully programmable environmental chamber control
  • Miniaturized analyzer in chamber head for more reliable measurement
  • Battery charge life - at least 8 hours
  • Advanced data capture and output capabilities with USB port and removable SD data card.
  • Automated post-processing and calculation of Rd, Γ*, gm, CC, VCMAX, JMAX & AMAX
  • Up to date lake and puddle model quenching protocols
  • Full environmental control
  • Diurnal measuring capability with external PAR sensor to allow the chamber to match ambient values.
  • Chamber temperature may be raised or lowered by 14oC above or below ambient.
  • Measures and corrects for atmospheric pressure.
  • Graphic touch screen color display
  • Option for automated modulated light intensity set up
  • The iFL - LCpro-SD is a portable integrated photosynthesis - chlorophyll fluorescence measuring system with fully programmable microclimate control. This system is very easy to use, yet repeatable, accurate and reliable. Its abilities to measure leaf absorptance, and provide white actinic light to allow more reliable leaf chloroplast migration, and leaf xanthophyll cycle adjustment make the iFL a technology leader. Furthermore, advanced automation software allows direct readout of gm, Rd, Γ*, CC, VCMAX, JMAX, chamber leakage corrections, and the results of A/CC curves. Leaf temperature is measured with a large area IR sensor for more reliable measurement. Programmable PAR intensity is maintained using a feedback loop using and a PAR sensor inside the measuring chamber. Ambient PAR can also be tracked and reproduced in the chamber with an external PAR sensor.  Battery charge life is at least 8 hours.

  • Parameters Measured and Protocols included:


    Selectable readout in either μmols, mmols, and moles, or in ppm and mbars.


    Quantum Yield of PSII (or ΔF/Fm' or Y(II)).


    Electron transport rate also known as ETR.


    Photosynthetically Active Region value.


    Leaf absorptance of PAR spectrum using RGB sensors above the leaf and below the leaf. Corrected for leaf transmittance.

    Chamber temperature:


    Leaf T:

    Leaf temperature is measured with an infrared sensor.

    Laisk protocol for Rd and Γ*.

    Yin protocol for Rd.

    Kok protocol for Rd.

    gm Mesophyll conductance.

    Cc - CO2 at the site of carboxilation.

    Γ* Compensation point absent of day respiration.

    Rd Respiration in the light.

    Rd, Γ* and other parameters or constants may also be input manually.

    Light curves & A/Q light response curves A/Ci curves, A/Cc curves.


    Maximum Photochemical efficiency of PSII.


    A more sensitive detector of stress than FV/FM, but it does not measure plant efficiency.


    Minimum fluorescence.


    Maximal fluorescence.


    Variable fluorescence.


    Maximal fluorescence with actinic illumination.

    FS (or F):

    Fluorescence under steady state conditions (prior to saturation pulse).


    (ΦPSII or ΔF/Fm') Quantum Yield of PSII.

    Rapid light curves



    A measure of a leaf's photosynthetic capacity or maximum electron transport rate

    α is the initial slope of line at low PAR values created by relating ETR to PAR. It provides a measure of quantum efficiency.


    The light intensity where ETRMAX occurs.

    Ik = rETRmax /α:

    A measurement of the light intensity where light saturation dominates, or the minimum saturation level.

    Hendrickson Quenching with NPQ:

    Y(NPQ), Y(NO), Y(II), NPQ, FV/FM.

    Kramer Quenching:

    qL, Y(NPQ), Y(NO), Y(II), FV/FM.

    Puddle model parameters:

    NPQ, qN, qP, Y(II), FV/FM.

    Walk Away automation sequence builder. Build a sequence, build a protocol, or stitch multiple protocols together.

    Fluorometer Specifications


    Light Sources:

    Saturation pulse:

    White LED with 690nm short pass filter. 7,500 μmols.

    Modulated light:

    660nm LED with 690nm short pass filter.

    Automated routine to optimally set the modulated light intensity. The modulated light may also be set manually.

    Actinic light source:

    White LED to 2000 μmols.

    Far red light:

    Above 740nm.

    Blue sensors for absorptance measurement.

    Red sensors for absorptance measurement.

    Green sensors for absorptance measurement.

    PAR Sensors:

    Two silicon diodes.

    One is inside the fluorometer chamber to measure PAR at the leaf level. It maintains a constant actinic light irradiation level throughout measuring routines, to ensure constant and proper intensity for steady state measurements. It is also used to measure absorptance diode intensity.

    The second PAR sensor is on top of the fluorometer. It can be used to measure and track or set ambient light irradiation at the angle of the leaf. This sensor can be used to match ambient PAR intensity in the leaf chamber in an automatic fashion. When it is desired, this feature can be used set light level on partly cloudy days to either sunny conditions, or cloudy conditions to minimized the time required to reach steady state conditions for ambient light measurements.

    Detection method:

    Pulse modulation method.

    Detector & Filters:

    A PIN photodiode with a 700nm ~ 750nm bandpass filter.

    Sampling Rate:

    Auto-switching from 10 to 10,000 points per second, depending on phase of test.

    FM' correction for all light adapted protocols. (According to Loriaux 2013). It may be turned on or off.

    Test Duration:

    Adjustable from 20 seconds to 160 hours.

    Storage Capacity:

    2 Gigabytes of non-volitile internal flash memory.

    Digital Output:

    USB, SD/MMC 2 Gigabyte data cards .

    Video output:


    User Interface:

    Display: Graphic color touch screen.

    Menu driven software.

    Battery Life:

    8 hours of continuous combined operation.

    Specifications subject to change without notice.

  • Small tripod

    All day carrying harness

    Optional measuring chambers

  •     PDF document.

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Opti-Sciences, Inc.     8 Winn Avenue      Hudson NH 03051       USA      (603)883-4400

Opti-Sciences, Inc.

8 Winn Ave

Hudson, NH 03051, USA

Phone: (603) 883-4400

Fax: (603) 883-4410