Celebrating our 35th year.
Quality Instrumentation for the Life Sciences

CIRAS-3 Redefining “portability” for high-level field research


The first truly mobile system for simultaneous measurement of photosynthesis and chlorophyll fluorescence. For field work, size and weight matter. At a weight of approximately 5 kg for both the console and cuvette, benefits include:

• Less site disturbance
• Easy access to hard-to-reach areas
• No need for a tripod or assistance
• Reduced fatigue
• An entirely new research experience

Powerful, Customizable & Intuitive

Our system is easy to use and highly intuitive. That means minimal training is needed, allowing you to begin collecting data shortly after your system arrives. Built-in system help dialogs are there to guide even the most inexperienced user every step of the way. Rely on the defaults or customize your own settings to monitor and display numerical and graphical data.

Environmental Control & Stability

The CIRAS-3 offers fully-automatic, complete and independent control of CO2, H2O temperature and light for response curves (i.e. fast A/Ci curves, light response, etc.). Control of all environmental parameters can be dynamic or preprogrammed. The CIRAS-3’s temperature stability and control is the most reliable in the industry. We also offer one of the widest temperature control ranges available with an extensive variety of different controlling options.

Measure Photosynthesis & Chlorophyll Fluorescence Simultaneously

Our CFM-3 Chlorophyll Fluorescence Module has a built-in light source. It can be used as both a fluorometer (PAM) and as an independent light source making it not only versatile but time and cost-efficient. Our unique “MultiPulse technology allows for the popular estimation of apparent Fm‘.

Rapid A/Ci Curves

Generate ultra-fast A/Ci curves in a fraction of the time using our innovative and programmable high-speed CO2 ramping technique.

Fast & Accurate

The CIRAS-3 is a true differential analyzer featuring four independent gas analyzers for CO2 and H2O. It’s compact size and small total system volume ensures the most rapid, accurate equilibration and leaf gas exchange measurement.

Plug & Play Accessories for Added Versatility

The CIRAS-3 can be used with a number of different leaf cuvettes for measurement of leaf gas exchange and chlorophyll fluorescence. It can also be used as a stand-alone CO2 and H2O differential gas analyzer. Measure insect respiration as well as soil CO2 efflux and net canopy flux using our chambers or yours. 

Auto Control of Light Intensity & Wavelength

Our PLC3 LED Light Units feature red, green, blue and white light enabling users to control both light intensity up to 2500 µmol m-2s-1 and proportion of light by wavelength.

No Calibration Required

Our Auto-Zero measurement principle ensures an inherent calibration stability confirmed by more than 35 years of experience in gas technology. It allows for fast warm-up, adaptation to changing ambient conditions and unsurpassed stability for many years. 

Highly Referenced

The CIRAS-3 is highly referenced in peer-reviewed published papers and journals, many of which are available on-line. 

Eliminating the obstacles while elevating the experience

Minimal Size. Maximum Performance.

The CIRAS-3 is designed with the high-level field researcher in mind. Its small size makes it the most mobile photosynthesis system of its kind, alleviating the need for assistance or tripods.

The innovative design of the CIRAS-3 utilizes its small system volume to ensure faster equilibration as well as the most rapid and accurate measurements available. Faster measurements allow the user to expand the parameters of their research and use their time and resources efficiently. Check out the size and weight of the CIRAS-3 console and leaf cuvettes and you will quickly discover why smaller and lighter is better.

Perform measurements in seconds with the CIRAS-3 Portable Photosynthesis System!

This measurement was performed on a Geranium outside our office in Amesbury, MA at a temperature of 19 0C and PAR of 1195 umol m-2 s-1.

Fast Response. Fully Mobile.

The location of the CIRAS-3’s IRGAs (Infrared Gas Analyzers) in the main console — right next to the internal gas mixing system and flow control — allows the CIRAS-3 to provide an ultra-fast response to changes in “reference” gas, and the fastest and most accurate mobile photosynthesis measurement available. IRGAs in the console makes the entire system highly portable, not to mention the added protection from dirt, dust, and debris commonly found in and around a leaf cuvette.

Packed with Power

Sound system electronics coupled with powerful Li-ion battery packs allows operation of the CIRAS-3 system for up to 12 hours. An important element of field work, you will find our batteries allow for a much longer duration of time in the field as well as eliminating the need to swap out batteries.

Create rapid A/Ci curves in minutes.

High-Speed CO2 Ramping Technique to Generate Rapid A/Ci Curves

For many years researchers have been regularly performing steady-state A/Ci curves on a wide variety of vegetation providing very useful information on plant status. The CIRAS-3 generates non-steady-state A/Ci curves in just a fraction of the time it takes to perform steady-state measurements based on our innovative High-Speed CO2 Ramping Technique. It is possible to generate A/Ci curves in less than 5 minutes with the CIRAS-3! However, the actual length of time to perform these measurements is highly dependent on user settings and parameters of interest.

Why are Researchers Interested in Rapid A/Ci Curves?

The purpose of performing non-steady-state A (Assimilation) vs. Ci (Intercellular CO2) curves is to provide two or sometimes three parameters for photosynthetic characteristics of leaves beyond those derived from any single A and Ci measurement. These parameters include:

  1. Maximum capacity of the ribulose bis-phosphate carboxylase enzyme
  2. Maximum rate of photosynthetic electron transport
  3. Maximum rate of triose phosphate utilization

Whether the third parameter can be quantified with this method depends on the metabolic properties of the leaf. The above three parameters, which are all temperature dependent, combined with stomatal conductance values, permit estimation of leaf photosynthesis under any combination of light, temperature, CO2, and humidity via the Farquhar, von Caemmerer, and Berry photosynthesis model.

One could obtain the same two or three parameters by doing slower, steady-state measurements of A at a range of Ci values, but that is quite time-consuming (generally at least 30 minutes, but sometimes up to one hour, as compared with possibly as little as 5 minutes per leaf with our ultra-fast A vs. Ci method).

How Does the CIRAS-3 Generate Ultra-Fast, Highly Accurate A/Ci Curve Data?

The CIRAS-3 features a highly accurate, true differential gas analysis system for both CO2 and H2O. It can easily, quickly and accurately linearly ramp the CO2 concentration in the leaf cuvette, producing a complete A vs. Ci curve in just minutes. Our unique Stored Differential Balance feature allows simplified data recordings and straightforward post-processing in Excel. Our response script editor allows users to easily generate and edit linear response scripts to meet their specific requirements.

Comparing Steady-State vs. Non-Steady-State A/Ci Curves.

CIRAS-3 rapid A/Ci curves

Comparison of a Non-Steady-State High-Speed A/Ci Ramping (black points) to traditional point-by-point Steady-State (red points) for a typical C4 Giant Foxtail leaf with PAR of 1500 µmol m-2 s-1 and Cuvette Flow of 300 ml/min. Reference CO2 ramped from 50 to 500 in 7 minutes. Each Steady-State point had an approximate 2 minute acclimation time for total data recording time of 18 minutes.

ciras3 rapid a-ci curves

Comparison of a Non-Steady-State High-Speed A/Ci Ramping (black points) to traditional point-by-point Steady-State (red points) for a typical C3 Soybean leaf with PAR of 1500 µmol m-2 s-1 and Cuvette Flow of 300 ml/min. Reference CO2 ramped from 100 to 1000 in 10 minutes. Each Steady-State point had an approximate 2 minute acclimation time for total data recording time of 22 minutes.

Our High-Speed CO2 Ramping Technique is featured in Plants

Our High-Speed CO2 Ramping Technique is featured in Plants as part of two separate scientific papers. One paper compares three independent methods of estimating mesophyll conductance. The second paper is related to soybean photosynthetic temperature responses. Our unique High-Speed CO2 Ramping Technique, coupled with our innovative Stored Differential Balance feature, is proven to be the fastest, easiest and most accurate way to generate non-steady-state A/Ci curve data to date.

See How Easy and Streamlined the Process is for Creating Rapid A/Ci Curves Using Our High-Speed CO2 Ramping Technique With Our CIRAS-3 Portable Photosynthesis System

A true differential analyzer for accuracy and reliability

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 are 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, expect accurate, reliable and stable calibration 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.

“The people working in my lab and I have been extremely satisfied with the CIRAS-3. We have found all of the CIRAS systems (my first was the CIRAS-1) to be easy to use and highly reliable.  In addition, the technical support and service at PP Systems is impeccable.”

— Bruce Schaffer, Ph.D.
University of Florida

Partial list of U.S. customers who count on the ultra-fast, highly accurate CIRAS-3:

  • Driscoll’s
  • Michigan State University
  • North Carolina State University
  • Ohio State University
  • Penn State University
  • Pioneer
  • Plenty
  • Purdue University
  • Texas A & M University
  • U.S. Department of Agriculture-ARS
  • U.S.D.A. Forest Service
  • University of Arkansas
  • University of California-Davis
  • University of Central Florida
  • University of Florida
  • University of Georgia
  • University of Massachusetts
  • University of Minnesota
  • Utah State University

Full environmental control:
Automated. Programmable. Standard.

CO2 and H2O Gas Analyzers

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 batteries (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 µmol 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 heatsink 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

Desiccants for Zero and CO2/H2O Control

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.

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 µmol 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

Meeting the demands of the serious researcher driving the future of science

Slide background
CIRAS-3 PLC Leaf Cuvettes
Lightweight. Fast. Precise.
• Truly plug and play
• Automatic temperature control
• Airtight seal without damage to vegetation
• Fastest response to CO2 and H20 changes
• Optional LED Light Unit (RGBW) available
• Field-customizable options
PLC3 Universal Leaf Cuvette shown.
PLC3 Conifer Leaf CuvettePLC3 Narrow Leaf CuvettePLC3 Universal Leaf CuvetteCiras3 cuvette options

Revolutionizing the Research Experience

Our PLC3 leaf cuvettes work seamlessly with the CIRAS-3. The innovative design makes for fast and efficient measurements just about anywhere!

No need for assistance or a tripod! Their small size and fast response further enhance the CIRAS-3’s capabilities. The CIRAS-3 supports three standard leaf cuvettes (Universal, Narrow, and Conifer) which are truly plug and play. Each cuvette connects directly to the CIRAS-3. No time-consuming, delicate reassembly or adjustment of different heads and sensors.

The leaf cuvette gaskets provide an air-tight seal without causing any damage to vegetation. Automatic temperature control is standard with all leaf cuvettes.

Onboard LCD Display

All PLC3 series leaf cuvettes include an onboard 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 flat, broad leaves

Our PLC3 Universal Leaf Cuvette is our most popular leaf cuvette by far. The PLC3 Universal is designed for measurement on most flat, broad leaf plants. It features 3 different windows allowing you to customize the head to accommodate different sized leaves.

Window: IR Filter
Dimensions: See head plates 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.

25 mm x 7 mm
Area: 1.75 cm2

18 mm Diameter
Area: 2.50 cm2

25 mm x 18 mm
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.

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”.

Measure photosynthesis & chlorophyll fluorescence simultaneously

The CFM-3 Chlorophyll Fluorescence Module

The CFM-3 Chlorophyll Fluorescence Module is capable of both independent measurement of chlorophyll fluorescence as well as 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 CIRAS-3’s MultiPulse technology produces a sequence of saturating light levels for estimation of apparent Fm‘.

The CFM-3 Chlorophyll Fluorescence Module is an optional accessory designed exclusively for use with the PLC3 Universal Leaf Cuvette.

simultaneous measurement

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

Powerful & Intuitive 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 input

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.

Highly customizable measurements

Configure graphical presentation of data the way you want it.

Streamlined navigation

All measurements & calculations can be viewed on one screen

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.

Fast and easy rapid A/Ci post processing
Highly customizable measurements

View CIRAS-3 data remotely from your PC

Powerful & Intuitive Software

CIRAS-3 Elevating the high-level field research experience

Product Features

  • Small footprint and lightweight–truly mobile, the first of its kind

  • Internal, rechargeable Li-ion batteries for up to 12 hours operation

  • 4 independent, non-dispersive infrared gas analyzers (IRGAs) for both CO2 and H2O

  • Automatic and programmable control of CO2, H2O, temperature, and light

  • 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 chlorophyll fluorescence, soil respiration, canopy assimilation and insect respiration