CIRAS-4 - Portable Photosynthesis Measurement System

CO₂ & H₂O Gas Analyzers

The heart & soul of any leaf gas exchange system

The backbone and most critical part of any leaf gas exchange system is the gas analysis system.  The CIRAS-4 is a true differential analyzer featuring four independent, non-dispersive infrared gas analyzers (IRGAs) ensuring the most accurate and reliable measurement and control of CO₂ and H₂O available.  For high-level research, this is a critical requirement and a major advantage over gas-switching systems.  For enhanced reliability, there are no moving parts and the optical bench is temperature-controlled and pressure compensated for the most accurate and reliable measurement of CO₂ and H₂O under changing ambient conditions.  Each gas analyzer includes an IR source, highly polished gold-plated sample cells, and detectors optimized for CO₂ (4.26 µm) and H₂O (2.60 µm).

Located in the console, the CIRAS-4's optical bench is safely protected and filtered from even the harshest of environmental conditions, eliminating the need for any user maintenance or cleaning. The IRGAs are located close to the internal gas mixing system, providing tight control of gas flow and ultra-fast response to changes in the reference CO₂ and H₂O gas supply. 

Our Unique Auto-Zero Technique

No factory recalibration required 

Expect nothing less than the most accurate, reliable, and stable calibration of CO₂ and H₂O for many years without the need for inconvenient, time-consuming, and costly return-to-factory calibration.  Our innovative, proprietary Auto-Zero measurement technique ensures inherent calibration stability that has been confirmed by more than 35 years of experience in gas analysis technology.  It allows for very fast warm-up, quick adaptation to changing ambient conditions, and excellent long-term stability.   Auto-Zero also minimizes effects on span gas sensitivity, IR source aging, as well as changes in detector sensitivity and electronics.  Simple, periodic system checks are recommended to confirm system integrity and calibration.  

CO₂ Measurement & Control

Automatic and programmable CO₂ control is standard with the CIRAS-4. PP Systems pioneered the method of controlling CO₂ back in 1992 (CIRAS-1) using mini CO₂ cartridges that are commercially available and easily sourced worldwide. Our proprietary gas mixing technology and CO₂ regulator provide accurate, stable, and constant flow of CO₂.   Each CO₂ cartridge provides at least 12 hours of continuous use in the field and our CO₂ regulator and cartridge holder are maintenance-free.

• Measurement Range: 0 – 10000 µmol mol^-1
• Control Range: 0 – 2000 µmol mol^-1

If required, the CIRAS-4 can easily be connected to an external CO₂ source as well as programmed and configured for ambient CO₂ measurements. 

H₂O Measurement & Control

PP Systems also pioneered the method of controlling H₂O automatically.  Programmable H₂O control is standard with the CIRAS-4.  Onboard, self-conditioning desiccants are used for controlling H₂O via user-defined settings.  The CIRAS-4 can control H₂O based on a percentage of ambient, VPD (Vapor Pressure Deficit), or to a specific H₂O concentration.  

• Measurement Range: 0 – 75 mmol m^-1
• Control Range: 0 – Dewpoint

The CIRAS-4 can easily be programmed for H₂O measurements above and below ambient, and can also be configured for ambient H2O measurements.

Temperature Measurement & Control

The CIRAS-4 features the widest range, as well as the fastest and most reliable temperature control in the industry.  Each leaf cuvette’s integral automatic temperature control is highly accurate and stable. Peltier coolers with heat sink and fan are mounted on all cuvette heads for precise control over a wide range of temperatures.  The CIRAS-4 can be programmed to control to a specific leaf temperature, a specific cuvette air temperature or to track leaf to ambient.  Temperature control can also be disabled.

• Control Limits: 0 – 45 °C
• Control Range: 12 °C below ambient to 15 °C above ambient

Light Measurement & Control

Automatic control of light intensity is achieved with our compact, low-power lightweight LED (RGBW-FR) light units available for each of our PLC4 Leaf Cuvettes.

• Measurement Range: 0 – 3000 µmol m^-2 s^-1
• Control Range: 0 – 2500 µmol m^-2 s^-1 

Each light unit features a bank of red, green, blue, and white LEDs as well as far-red LEDs to allow users control of up to 30% of PAR light intensity. In addition to controlling light intensity, you can also control the proportion of light by wavelength, which can be especially useful for research on plant responses to different wavelengths.

CFM-4 Chlorophyll Fluorescence Module

If your research includes chlorophyll fluorescence, the CFM-4 Chlorophyll Fluorescence Module can measure chlorophyll fluorescence and photosynthesis simultaneously.

MultiPulse™ Technology for Accurate Estimation of Fm’
The CFM-4 is capable of delivering high-saturating pulses up to 10000 µmol m^-2 s^-1. The CIRAS-4 is the only system available that features our innovative MultiPulse™ technology. MultiPulse™ produces a sequence of user-defined, lower-saturating pulse light levels, avoiding the risk of photodamage to the leaf while accurately estimating apparent Fm‘.
A pulse-amplitude-modulated (PAM) fluorometer, the CFM-4 provides both dark- and light-adapted chlorophyll fluorescence measurement parameters including photochemical vs. non-photochemical quenching and electron transport rate.

Three Instruments in One!

The CFM-4 is elegantly designed with all light sources and fluorescence detection capability built directly into one lightweight, compact unit.  The CFM-4 can also act as an actinic light source for leaf gas exchange as well as a stand-alone fluorometer when leaf gas exchange data is not required.

OJIP Fast-Induction Kinetics

The CFM-4 provides OJIP fast-induction kinetics. OJIP-related data are easily stored and exported for further analysis providing additional fluorescence-related calculations.

Multiple Leaf Apertures

The compact module is lightweight (0.3 kg), truly plug and play, and allows the user to measure chlorophyll fluorescence over the entire leaf area using any of the three leaf head plates that come standard with the PLC4 Universal Leaf Cuvette.

Automatic Control

Users can automatically control temperature and light intensity as well as proportion of red, blue, green, white, and far-red LEDs.

• Temperature Control Range: 12 °C below ambient to 15 °C above ambient
• Light Control Range: 0 – 2500 µmol m^-2 s^-1
• Far-Red Control Range: 0 - 30% of PAR  

PLC4 Universal Leaf Cuvette

The PLC4 Universal Leaf Cuvette measures most flat, broad leaf plants and comes standard with three interchangeable window head plates that are easy to swap out, allowing you to accommodate a wide range of different leaf sizes. A technologically advanced infrared (IR) sensor provides accurate, non-contact measurement of leaf temperature. Leaf temperature can also be determined by energy balance.

PLC4 Broad/Narrow/Conifer Leaf Cuvette

The PLC4 Broad/Narrow/Conifer Leaf Cuvette comes with three interchangeable heads for measurement on large, flat broad leaves, narrow leaves, grasses, and conifers. Leaf temperature is measured via the non-contact infrared (IR) sensor, directly using a precision thermistor or calculated using energy balance.

• Fast equilibration & response time: Overall small system volume means almost immediate response times and fast equilibration.
• Head plates secured by magnets: All head plates are secured in place by magnets for quick and easy change out in the lab or field.
• Rulers on apertures: Rulers are available on larger head plates to assist with better leaf area approximation.
• Minimal boundary layer resistance: Advanced air mixing inside the chamber reduces boundary layer resistance.
• Temperature control: All PLC4 Leaf Cuvettes offer a temperature control range of approximately 12°C below ambient up to 15°C above ambient with 0.1°C precision.
• PAR: Two miniature PAR sensors provide a highly reliable average of PAR inside the cuvette. Ambient PAR is measured by an external sensor with industry-standard calibration and cosine correction.  
• Easy & accurate leak diagnosis: Direct pressure measurement inside the cuvette allows for easy and accurate leak diagnosis.

Optional LED light units are available for automatic control of light for all PLC4 leaf cuvettes. Each light unit features a bank of red, green, blue, white, and far-red LEDs (RGBW-FR) allowing for automatic control of both light intensity up to 2500 µmol m-2 s-1 and proportion of light by wavelength.  All light units are designed to ensure uniform light distribution over the entire leaf area for accurate results.Far-redOur PLC4 leaf cuvettes also include 4 far-red LEDs. CIRAS-4 users can control far-red up to 30% of PAR, allowing users to more accurately recreate the natural light environment. 

Wavelength (RGBW)      Color Peak Full      Width at Half Max      Light Control Range

Red                                  625 nm ± 5 nm       15 nm                         0 – 2500 µmol m^-2 s^-1

Green                               528 nm ± 8 nm       40 nm

Blue                                 475 nm ± 10 nm     28 nm

White                               425 – 700 nm

Far-red                             730 nm ± 5 nm      31 nm