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Enabling better global research outcomes in soil, plant & environmental monitoring.


The DUAL-KLAS-NIR represents a significant advancement over the well-established DUAL-PAM-100 system. The DUAL-PAM-100 employs one pair of wavelengths in the near infrared (NIR) to measure absorption changes related to redox alterations of the photosystem I reaction center. Using four wavelength pairs in the NIR, the DUAL-KLAS-NIR is capable of unequivocally discriminating redox changes of plastocyanin (PC), PS I reaction center (P700) and ferredoxin (Fd).

By applying an innovative analytical approach, the DUAL-KLAS-NIR acquires the in vivo spectral characteristics of pure PC, P700 and Fd. This spectral information allows to monitor online the redox changes of P700, PC and Fd, and to determine ratios of PC/P700 and Fd/P700.

Like the DUAL-PAM-100, the DUAL-KLAS-NIR is also a PAM chlorophyll fluorometer. The device can excite fluorescence by green or blue PAM measuring light. Green light penetrates deeper than blue light into the leaf. Thus, green-excited fluorescence includes information from deeper leaf layers and, thus, is well-suited for comparison with the NIR absorption measurements which always probe the entire leaf.

The software of the DUAL-KLAS-NIR shares many features with that of the DUAL-PAM-100. Hence, getting started with the DUAL-KLAS-NIR is particularly straightforward for users of the DUAL-PAM-100. Using automated measuring routines of DUAL-KLAS-NIR software, even complex measuring protocols can be easily performed.

DUAL-KLAS NIR instruments can measure in 1, 2 or 6 channel mode, with time resolutions of 35 µs, 150 µs and 1 ms, respectively.

The pulse modulation technique developed for the DUAL-PAM-100, in which the different channels are measured as blocks of 50 µs, has been extended for the DUAL-KLAS-NIR to accommodate 6 channel measurements (see Fig. 2).

The DUAL-KLAS-NIR uses green measuring light for the fluorescence measurements to get the best possible match between fluorescence and absorbance measurements. A second fluorescence channel detects the fluorescence induced by blue measuring light. The blue measuring light gives more specific information on the upper or lower side of the leaf and in addition gives a fluorescence signal that is one order of magnitude larger than the signal induced by the green measuring light.

Other Distinctive Features of the DUAL-KLAS-NIR

  • Integrated red, blue, far-red actinic LEDs, whereby the 635 nm red LED-array is used as the light source for continuous actinic light, multiple turnover pulses and single turnover flashes. The blue 460 nm LED in the detector unit allows a continuous illumination with 300 µmol m-2 s-1 from the detector side of the sample.
  • The measurement of four wavelength pairs in the near-infrared: 785-820, 820-870, 870-950, 840-950 nm.
  • Both sides of the leaf can be illuminated to achieve the most homogeneous illumination of the leaf possible.
  • An extremely wide range of measuring light frequencies (1 Hz to 400 kHz allows continuous assessment of the FO level as well as recording of fast kinetic transients at high time resolution (e.g. the polyphasic fluorescence rise or flash relaxation kinetics).
  • All light sources can be switched with 2.5 µs time resolution under software control. If single channel measurements are made, a script is available with which the different signals can be measured consecutively at high time resolution.
  • Other important technical features are: 1. Automated Slow Kinetics recordings; 2 pre-programmed Triggered Runs; 3. on-line and off-line averaging; 4. Operation of the instrument via automated measuring routines (script file programming).

Scheme showing how the different light sources and the photodiode are oriented relative to each other in the DUAL-KLAS-NIR. ML = measuring light, AL = actinic light, ST = single turnover flash, MT = multiple turnover pulse, FR = far-red light, COB = chip-on-board (LED-array).

Scheme showing how the wavelength pairs are measured sequentially in blocks of 50 µs after which the signals after a few more steps, with the help of the differential model plots, are deconvoluted and turned into PC, P700 and Fd signals.

Power-and-Control-Unit DKN-C
General design: Microcontroller: 4 x AVR-RISC (8 MHz) + 4 MB SRAM; 256 000 data points with 12 bit resolution can be stored
Communication: PC interface: USB 1.1, 2.0 and 3.0 compatible
User interface: Windows computer (Windows 8/10) with KLAS-100 software
Power supply: Windows computer (Windows 8/10) with KLAS-100 software
Power consumption: During basic operation 350 mA
Sockets: 6 ports for heads (power for single wavelength (2 channels) and double wavelength (4 channels) modulated measuring light, power for 2 actinic LED arrays (one in DKN-E and one in DKN-D) and 1 NIR measuring light LED array (in DKN-E), input for 2 detectors (the photodiode detector of DKN-D is connected to detector 1), socket for stirrer (plus speed controller and standby switch), AUX (for Spherical Micro Quantum Sensor US-SQS/WB or Cosine-Corrected Mini Quantum Sensor US-MQS/WB), USB (for USB cable), TRIGGER OUT (output of 5 V rectangular signals to trigger external devices), 2 EXT. SIGNALS (input for external DC signals. Range 0-1 V or 0-5 V), and CHARGE (for MINI-PAM/L charger).
Dimensions: 36 cm x 16 cm x 26.5 cm (W x H x D), with carrying handle
Weight: 5.8 kg
Emitter unit DKN-E
Measuring light: Chip-On-Board LED array for pulse-modulated 780, 820, 840, 870 and 965 nm NIR measuring light, pulse modulated green, fluorescence measuring light (540 nm).
Actinic light: Chip-On-Board LED array (635 nm) for continuous red actinic illumination (max. 2500 µmol photons m-2 s-1 PAR), which can also be used for single turn over flashes (max. 250000 µmol photons m-2 s-1 PAR, length 5-50 µs), and multiple turnover pulses (MT and SP) (max. 25000 µmol photons m-2 s-1 PAR, length 1-1000 ms).
Dimensions: 5.5 cm x 9 cm x 4 cm (W x H x D)
Weight: 560 g (incl. cables, 1.4 m long)
Detector unit DKN-D
Measuring light: Pulse modulated blue fluorescence measuring light (460 nm).
Actinic light: Blue light (460 nm) for continuous blue illumination (max. 300 µmol m-2 s-1 PAR), Chip-On-Board LED array (635 nm) for continuous red illumination (max. 2500 µmol m-2 s-1 PAR), which can also be used for saturating single turnover flashes (max. 250000 µmol m-2 s-1 PAR, length 5-50 µs), and multiple turnover pulses (MT and SP) (max. 25000 µmol photons m-2 s-1 PAR, length 1-1000 ms), far-red light (740 nm) for continuous far-red illumination (max. 400 µmol photons m-2 s-1).
Signal detection: Photodiode and pulse preamplifier to measure four dual wavelength NIR-transmission difference signals (780-820, 820-870, 870-965 and 840-965 nm) and two fluorescence signals. Time resolution of a single channel measurement is 35 µs, of a two channel measurement is 150 µs and of a 6 channel measurement is 1 ms. The same detector (protected by the same set of filters) is used for fluorescence and NIR transmission measurements. The filter set passes wavelengths > 750 nm.
Dimensions: 5.5 cm x 9 cm x 4 cm (W x H x D)
Weight: 540 g (including cables, 1.4 m long)
Transport Box DKN-T
Design: Aluminium box with custom foam packing for DUAL-KLAS-NIR and accessories
Dimensions: 60 cm x 40 cm x 34 cm (L x W x H)
Weight: 5 kg
Linear Positioning System 3010-DUAL/B
Design: Consisting of black anodised aluminium baseplate with gear rack on which one measuring head holder is mounted on a movable stage which can be precisely positioned along the gear rack by a lateral adjustment knob. Includes a 13 cm lab stand rod which can be screwed onto the bottom of the baseplate, and a 3 mm Allen wrench
Dimensions: 18.5 cm x 11.5 cm x 12 cm (L x W x H, max. without lab stand rod)
Weight: 1050 g
DUAL-PAM-100 Gas-Exchange Cuvette 3010-DUAL
Design: Cuvette consisting of a sandwich of two 2 x 2 cm aluminium frames, each holding the end part of a Walz standard Perspex rod to connect various measuring heads of the DUAL-KLAS-NIR. Sealing material between frames and leaf: silicon foam gasket. Distance between Perspex rod and leaf: ca. 1 mm on each leaf side. Pneumatically separated upper and lower cuvette halves, controlled by a regulator unit with sockets for cable connections to the 3000 C control unit of the GFS-3000. Leaf area examined: 1.3 cm2. Leaf temperature measurement: thermocouple, range -10 to +50°C, accuracy ±0.2°C. External cosine-corrected Micro Quantum Sensor MQS/A for PAR measurements ranging from 0 to 2500 µmol m-2 s-1, accuracy ±5%
Operating temperature: -5 to +45°C
Dimensions: Assembled cuvette: 10 cm x 4 cm x 12 cm (L x W x H), electronic box: 7 cm x 7 cm x 15 cm (L x W x H)
Weight: Cuvette, regulator unit, cables, and mounting frame: 1.7 kg; mounting stand ST-101: 2 kg
Optical Unit for Suspensions ED-101US/MD
Design: Black anodized aluminium body with central 10 x 10 mm standard glass cuvette; for attachment of Emitter Unit DKN-E, Detector Unit DKN-D and Miniature Magnetic Stirrer PHYTO-MS; additional ports for attachment of two additional Emitter or Detector Units.
Weight: 750 g
Accessories for ED-101US/MD
Temperature Control Block ED-101US/T: Sectioned block with central 10 x 10 mm opening to be mounted on top of the ED-101US/MD unit; to be connected to external flow-through water bath (not included), weight 250 g
Miniature Magnetic Stirrer PHYTO-MS: Based on device manufactured by h+p (type Variomag-Mini); featuring adapter to be mounted in bottom port of the Optical Unit ED-101US/MD; powered and controlled by the Power-and-Control-Unit DKN-C
Spherical Micro Quantum Sensor US-SQS/WB: 3.7 mm ø diffusing sphere coupled to integrated PAR sensor via 2 mm diameter fiber; compact amplifier unit and special holder for mounting on Optical Unit ED-101US/MD; to be connected to the Power-and-Control Unit DKN-C
Temperature Control Unit US-T
Power-and-Control Unit US-T/DR
Display: Three line LCD display
Control range: 0°C to 50°C at 0.1 K steps
Operating voltage: 11 V – 14 V DC
Maximum Peltier current: 1 A
Size: 105 mm x 90 mm x 130 mm (W x H x D)
Weight: 0.57 kg
Peltier Heat-Transfer Head US-T/DS
Achievable temperatures: 12 K below ambient temperature, 15 K above ambient temperature (Quartz cuvette placed in Optical Unit for Suspensions ED-101US/MD with 1.5 mL water and stirrer PHYTO-MS on)
Size: ø 55 mm, 110 mm height
Cable length: 130 cm
Weight: 0.29 kg (including cable)
AC Adapter
Input: 100 V – 240 V AC, 1.5 A 50-60 Hz
Output: 12 V DC, 5.5 A
Size: 130 mm x 56 mm x 30 mm (L x W x H)
Weight: 0.50 kg (including cable)
Cuvette for Low-Drift Absorbance Measurements DUAL-K25
Design: Quartz glass cuvette, cross section: 10 mm x 10 mm, external dimensions: 12.5 mm x 12.5 mm x 26 mm (L x W x H). Special cuvette holder to position the cuvette between the Detector and Emitter Units DKN-D and DKN-E of the DUAL-KLAS-NIR. U-shaped black anodised aluminium shields to screen out external light. Three sealing gaskets to protect lower measuring head from spills.