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Quality Instrumentation for the Life Sciences

CIRAS-3: For high-level research, there is no substitute when it comes to technical specification, accuracy, reliability, and portability–the most mobile leaf gas exchange system available.

Check out our CIRAS-3 video below to learn more.

CO2 and H2O Gas Analyzers

The heart and soul of any photosynthesis system is the analyzer.  Accurate, reliable and stable measurement and control of CO2 and H2O is critical for high-level research.  The CIRAS-3 is a “true differential analyzer” featuring 4 independent, non-dispersive gas analyzers for accurate, simultaneous measurement and control of both CO2 and H2O.  This is a significant advantage over “gas switching” systems and a major requirement for most researchers.  For enhanced reliability, there are no moving parts such as chopper motors or filter wheels.  The gas analyzers include an infrared source, highly polished, gold plated sample cells and detectors that are optimized for CO2 (4.26 µm) and H2O (2.60 µm).  The analyzers act as absorptiometers measuring infrared absorption only.  The optical bench is temperature controlled and pressure compensated ensuring the most accurate measurement of CO2 and H2O under changing ambient conditions.

Measurement Ranges

  • CO2: 0-10000 µmol mol-1
  • H2O: 0-Dewpoint


The design of the CIRAS-3 ensures an inherent calibration stability that has been confirmed by over 35 years of experience in gas analysis technology.  The CIRAS-3 features an innovative Auto-Zero function that allows for fast warm-up, adaptation to changing ambient conditions and excellent stability.  In short, you can expect your calibration to be accurate, reliable and stable for many years without the need for time-consuming, expensive recalibration.  The Auto-Zero function minimizes effects on span (gas sensitivity) of sample, source aging, changes in detector sensitivity and changes in pre-amplifier gain.  Periodic system checks are simple and recommended to confirm system integrity and calibration.

Environmental Control

The level of environmental control in the field with the CIRAS-3 is unsurpassed.  The CIRAS-3 offers complete, independent and automatic control of CO2, H2O, temperature and light for response curves (i.e. A/Ci curves, light response, etc.) with fast time response.  Control over all environmental parameters can be dynamic or pre-programmed for automated response curve generation.  All power required for environmental control is provided by the internal rechargeable Li-ion battery (no external power supply is required).

CO2 Control – Unlike some systems, automatic CO2 control is standard with the CIRAS-3.  Our innovative, integral gas blender and regulator mixes pure CO2 provided by mini CO2 cartridges (8 g) with CO2 free air to provide a very accurate, stable, continuous and constant flow of CO2.  Each CO2 cartridge is capable of providing up to a minimum of 12 hours continuous use.  It is very easy to change out cartridges and there is little to no maintenance required for the CO2 gas blender or regulator.

  • CO2 Control Range: 0-2000 umol mol-1

H2O Control – On-board, self-indicating desiccants are used for conditioning the H2O concentrations per user selected intervals.

  • H2O Control Range: 0-Dewpoint

Measurements above ambient are also easily achieved.

Temperature Control – Automatic, accurate and stable temperature control is standard and integral with all leaf cuvettes.  Peltier elements are mounted to the head along with heat sink and fans for precise control of temperature over a wide range.  The user has the ability to disable temperature control, track ambient or to control at a set temperature.

  • Temperature Control Range: ~10 oC below ambient to 15 oC above ambient
  • Ambient Temperature Limits: 0-45 oC
Field measurement of leaf gas exchange with the CIRAS-3 Portable Photosynthesis System

Product Features

  • Small footprint and lightweight–truly mobile, the first of its kind
  • Internal, rechargeable Li-ion batteries providing up to 12 hours operation
  • 4 Independent, non-dispersive infrared gas analyzers for both CO2 and H2O
  • Large, full color, 7.0″ transflective LCD for field use and optimized viewing angle
  • Unlimited data storage (internal memory and thumb drives)
  • Flexible and versatile user interface
  • Powerful software
  • Range of accessories for soil respiration, canopy assimilation and chlorophyll fluorescence
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Back of Console

CIRAS-3 rear panel

CIRAS-3 back panel featuring CO2 cartridge holder, gas and electrical connections and desiccants for instrument zero and CO2/H2O control.

Light Control (Optional)

Automatically control both light intensity and proportion of light by wavelength.

LED Light Unit (RGBW) for CIRAS-3

All leaf cuvettes can be supplied with an optional, compact LED light unit for automatic control of light. Each light unit features a bank of red, green, blue and white LEDs (RGBW) allowing for control of both light intensity and proportion of light by wavelength.

  • Light Control Range: up to 2500 umol m-2 s-1 (Depends on Light Unit type)

Wavelength (RGBW)

  • Red Peak Wavelength: 625 nm +/- 5 nm, FWHM: 15 nm
  • Green Peak Wavelength: 528 nm +/- 8 nm, FWHM: 40 nm
  • Blue Peak Wavelength: 475 nm +/- 10 nm, FWHM: 28 nm
  • White Wavelength: 425-650 nm

CFM-3 Chlorophyll Fluorescence Module (Optional)

Measure photosynthesis and chlorophyll fluorescence simultaneously in one truly portable and integral system.

CFM-3 Chlorophyll Fluorescence Module for use with CIRAS-3 Portable Photosynthesis System

The CFM-3 Chlorophyll Fluorescence module is an optional accessory for use with the PLC3 Universal Leaf Cuvette only.  It is capable of both independent measurement of chlorophyll fluorescence and simultaneous measurement of photosynthesis and chlorophyll fluorescence.  The CFM-3 is compact and elegantly designed with all light sources and fluorescence detection capability built directly into the light unit.  The CFM-3 can be used as an actinic light source for leaf gas exchange and as a pulse-amplitude modulated (PAM) fluorometer for measurement of chlorophyll fluorescence on both dark and light adapted vegetation. The CFM-3 is capable of delivering saturating pulses up to 10000 µmol m-2 s-1 which is extremely useful in accommodating a wider range of ambient light conditions.  The system is also capable of producing a “Multiphase flash” allowing for estimation of apparent Fm‘.

Measured and Calculated Fluorescence Parameters

  • Fo, Fm, Fs, Fo’, Fm’, Fv/Fm, ϕPSII, J, Fv’/Fm’, qP, qNP, NPQ, qL, ϕNO, ϕNPQ-K, ϕfD and ϕNPQ-G

User Interface & Software

The CIRAS-3 main console incorporates a large, full color 7.0” WSVGA transflective display featuring superb readability under all ambient conditions including full sunshine.   The display is custom designed with a 30o viewing angle making it easier to read from different positions ensuring measurements can be performed and recorded by just one person.   A custom, 27 tactile feel keypad is available for all user inputs.

Data Presentation

Customize the information that you would like to be presented on the LCD under your system preferences. Many of the displays and presentation of data is user definable.

Data Collection and Transfer

With just a few key presses manual, automatic and response curves can be created, run and saved to internal memory or to a convenient USB thumb drive (memory stick).  Data storage is flexible and unlimited and can easily be transferred to your PC for further analysis in your favorite spreadsheet program.

Measured and Calculated Photosynthesis Parameters

CO2 reference, CO2 analysis, CO2 differential, H2O reference, H2O analysis, H2O differential, air temperature, leaf temperature, cuvette temperature, PAR internal, PAR external, relative humidity, atmospheric pressure, flow, Ci, gs, A, E, VPD and WUE.


Programming simple or complex experiments could not be any easier.  Users can create their own response curves using the popular XML programming language.  Once created, programs can be downloaded to the CIRAS-3 or even shared with other CIRAS-3 users.

CIRAS-3 graphical presentation of data

Configure graphical presentation of data the way you want it.

CIRAS-3 numerical data presentation of data

All measurements and calculations can be viewed on one screen

Leaf Cuvettes & Accessories

The CIRAS-3 can be supplied with 3 standard leaf cuvettes (universal, conifer and narrow) which are truly plug and play. Each cuvette can be connected directly to the CIRAS-3 main console without the need for time consuming, delicate re-assembly and adjustment of sensor heads and calibration. All leaf cuvette materials are carefully selected to minimize influences such as infrared radiation, water sorption, CO2 effects and leaks. The leaf cuvette gaskets provide a good seal without causing any damage to vegetation. Automatic temperature control and on-board LCD are standard with all leaf cuvettes.

On-Board LCD

Focus on what’s important, the leaf and measurement status.

LCD display on PLC3 Universal Leaf Cuvette

All PLC3 series leaf cuvettes include an on-board LCD allowing the user to display up to 8 user defined parameters.  Measurements can also be recorded remotely from the leaf cuvette for convenience and ease.

PLC3 Universal Leaf Cuvette

For measurement on flat, broad leaves.

PLC3 Universal Leaf Cuvette
  • Window: IR Filter
  • Dimensions: See windows below

Includes 2 miniature silicon photodiode sensors providing a reliable average of PAR inside the cuvette in addition to ambient PAR measured by an external sensor.  It also includes an infrared (IR) radiation sensor for accurate, non-contact measurement of leaf temperature.  Leaf temperature can also be determined by energy balance.

The PLC3 Universal includes 3 different windows allowing you to customize the head to for different size leaves.

PLC3 Universal 25 mm x 7 mm window

25 mm x 7 mm

Leaf Area 1.75 cm²

PLC3 Universal 18 mm diameter window

18 mm diameter

Leaf Area: 2.5 cm²

PLC3 Universal 25 mm x 18 mm window

25 x 18 mm

Leaf Area: 4.5 cm²

PLC3 Conifer Leaf Cuvette

For measurement on grasses, cereal crops and short needle conifers.  The window is hemispherical making it suitable for 3D structures.

  • Window: Glass
  • Window Area: 80 mm (L) x 40 mm (Diameter)

Includes 1 miniature silicon photodiode sensor providing measurement of PAR inside the cuvette in addition to ambient PAR measured by an external sensor.  Leaf temperature is calculated based on energy balance or precision thermistor for contact measurement.  An optional head plate can be supplied to easily convert from “conifer” to “narrow”.

PLC3 Narrow Leaf Cuvette

For measurement on grasses, cereal crops and long needle conifers.

PLC3 Narrow Leaf Cuvette
  • Window: IR Filter
  • Window Area: 80 mm (L) x 30 mm (W)

Includes 1 miniature silicon photodiode sensor providing measurement of PAR inside the cuvette in addition to ambient PAR measured by an external sensor.  Leaf temperature is calculated based on energy balance or precision thermistor for contact measurement.  An optional head plate can be supplied to easily convert from “narrow” to “conifer”.

PC Utility Software & Remote Display

Programming simple or complex experiments from a PC could not be any easier. Users can create their own response curve scripts using the popular XML programming language. Once created, programs can be downloaded to the CIRAS-3 console or shared with other researchers that might want to replicate measurements.

PC Utility software for remote programming of scripts
PC Utility software for remote display of CIRAS-3 data

View CIRAS-3 data remotely from your PC