IMAGING-PAM

Imaging-PAM technology brings the power of the proven Pulse-Amplitude Modulation (PAM) principle into the realm of high-resolution, image-based chlorophyll fluorescence analysis. This cutting-edge approach delivers detailed, spatially precise insights into photosynthetic performance - non-invasive, highly sensitive, and ideal for capturing the dynamic responses of plants under real-world conditions. From fundamental plant physiology to advanced research on photosynthetic efficiency, stress resilience, and environmental toxicology, Imaging-PAM systems offer researchers an exceptional window into the function and health of photosynthetic organisms.

The IMAGING-PAM family - comprising the MAXI, MINI, and MICROSCOPY versions - stands out through its modular, forward-looking design. All systems operate with the same Multi Control Unit IMAG-CG, and the camera can be used interchangeably across versions. This versatility enables seamless adaptation to different experimental requirements, applications, and magnifications, making the IMAGING-PAM M-Series both cost-effective and exceptionally flexible. In addition, all systems can be fully programmed for automated measurement routines and operated remotely, supporting long-term experiments and high-throughput workflows with minimal manual intervention.

For even deeper physiological insights, the MAXI and MINI versions can be combined with the Gas-Exchange System GFS-3000. This powerful integration merges spatially resolved fluorescence imaging with precise analysis of photosynthetic carbon fixation—creating a comprehensive platform for understanding photosynthesis across multiple scales.

Chlorophyll fluorescence is a very sensitive indicator of photosynthesis. Quantitative information on the quantum yield of photosynthetic energy conversion is obtained by PAM fluorometry and the saturation pulse method (Schreiber U (2004) Pulse-Amplitude-Modulation (PAM) Fluorometry and Saturation Pulse Method: An Overview, pp. 279-319. Kluwer Academic Publishers, Dordrecht, The Netherlands).

A wide range of photosynthetic parameters can be derived from fluorescence measurements, giving insight into the physiological state of all photosynthetically active organisms, including higher plants, mosses and ferns as well as various types of algae, phytoplankton and biofilms.

With the advance of highly sensitive CCD cameras and extremely powerful light-emitting diodes (LEDs), the development of IMAGING-PAM fluorometers has become possible systems that not only record images of chlorophyll fluorescence but are also fully capable of delivering all relevant chlorophyll fluorescence parameters using the saturation pulse method. This enables researchers to obtain detailed images of photosynthetic activity and to track its spatio-temporal variations with high precision. The newest addition to this technology platform, the HEXAGON-IMAGING system, is equipped with far-red (FR) LEDs that open up advanced experimental capabilities, including state-shift experiments and accurate Fo′ determinations.

All IMAGING-PAM fluorometers provide images for 17 different parameters. The fluorescence parameter Ft is monitored continuously, while Fo and Fm are determined after dark adaptation and serve as key references for fluorescence quenching analysis using the saturation pulse method. In addition to Fv/Fm, the maximum quantum yield of PS II after dark acclimation, the systems also deliver images of the effective PS II quantum yield during illumination (Y(II)), the quantum yields of regulated and non-regulated energy dissipation (Y(NPQ) and Y(NO)), as well as the apparent electron transport rate (ETR and PS).

A dedicated routine for measuring a PAR-absorptivity image is available for both the MAXI and MINI versions of the IMAGING-PAM. This “Abs.-image,” based on NIR and red-light remission, allows for direct calculation of the apparent rate of photosynthesis for each pixel—eliminating the need to rely on the commonly used universal PAR-absorptivity mean value of 0.84 (ETR). In addition, the parameter PS/50 is displayed to visualize apparent photosynthesis using the same intuitive false-color coding employed for all other photosynthesis parameters.

The IMAGING-PAM M-Series offers a broad range of configurations tailored to different research applications. The MAXI, MINI, and MICROSCOPY versions are available with various optical geometries and excitation wavelengths, ensuring optimal performance across diverse sample types. While blue excitation light is typically used for fluorescence imaging in higher plants and algae, red–orange excitation is recommended for cyanobacteria to maximize signal quality.

All measuring heads can be equipped with specialized LEDs and dedicated filter sets for imaging fluorescence from reporter molecules such as GFP. The use of high-performance power LEDs enables actinic light intensities of up to 5000 μmol m⁻² s⁻¹ (depending on the specific M-Series model and configuration), allowing precise simulation of high-light stress and dynamic illumination conditions.

The systems also support measurements under continuous ambient light, making them suitable for field-like conditions or experiments where natural illumination is required. For PSII fluorescence measurements under such ambient light settings, IMAGING-PAM devices can communicate directly with the Universal Light Meter ULM-500, enabling real-time ambient light values to be automatically integrated into the IMAGING-PAM report file.

For measurements involving liquid suspensions, additional filter plates are available to improve image quality even when workingthrough reflective surfaces. To support combined measurement techniques, such as simultaneous PSII imaging and gas-exchange analysis, dedicated adapters are available. These accessories allow researchers to integrate PSII imaging within controlled environmental conditions or pair it with complementary methods like gas exchange, expanding experimental flexibility and enabling truly comprehensive photosynthesis research.