For probing of microscopic objects down to the single chloroplast

The MICROSCOPY-PAM is an extremely sensitive non-imaging chlorophyll fluorometer specialized to measure smallest spots in microscopic specimen like tissue preparations or suspensions.

Essentially, the fluorometer consists of a modified epi-fluorescence microscope equipped with a modulated LED light source and a photomultiplier for detection of modulated chlorophyll fluorescence.

MICROSCOPY-PAM: Modified Zeiss microscope and PAM-CONTROL interface


Standard Components

The MICROSCOPY-PAM system uses a Zeiss AxioScope.A1 epifluorescence microscope. By default, the microscope is equipped with a wide-aperture Zeiss Fluar objective with 20-fold magnification. Standard light source for fluorescence excitation is the blue Zeiss LED-Modul 470 nm.

A special pulse modulation regime permits the use if the same LED module as source for measuring and actinic light as well as for saturation pulses. The use of other Zeiss LED modules emitting at different wavelengths in the UV-A and visible spectral range will be considered on customer request.

Zeiss AxioScope.A1

Chlorophyll fluorescence is detected by a photomultiplier mounted on a special detector-ocular of the microscope. The ocular is equipped with an iris diaphragm with which the field of view can be narrowed down. A special dichroic beamsplitter filterset serves for effective separation of broadband fluorescence emission (λ>650 nm)

Photomultiplier PM-MF mounted on microscope using adapter set MC-A

Fluorescence excitation and detection are controlled by the PAM-CONTROL unit which allows stand-alone operation of the MICROSCOPY-PAM but can also function as a physical interface for computer-controlled operation of the system.

The PAM-CONTROL unit is delivered with WinControl V.2-Software for operation by Windows computers, an RS 232 cable, a USB-RS 232 adapter (in case that an RS-232 port is not available), a charger MINI-PAM/L, a cable to connect a chart recorder and a transport box.


Universal Control Unit

The PAM-CONTROL unit can conduct independently PAM fluorescence measurements but it can also act as physical interface between fluorometer and computer using WinControl V. 2 software.

The PAM-CONTROL unit is specialized to operate various extremely sensitive setups for chlorophyll fluorescence measurements: the MICROSCOPY-PAM, the MICROFIBER-PAM and the WATER-PAM.

Universal control unit for ultrasensitive chlorophyll fluorescence measurements in a variety of specialized optical geometries

Common to these three setups is the use of the same light-emitting-diodes (LED) as sources of measuring and actinic light, as well as for saturation pulses. Also, all setups use ultrasensitive photomultipliers: as a consequence, they are not suited for operation in the presence of non-modulated background light which would interfere with chlorophyll yield determinations.

The capacity of data storage comprises 4000 data sets. An extensive menu provides full control of instrumental settings and a variety of measuring protocols.

Schematic representation of Universal Control Unit PAM-CONTROL

Micro Quantum Sensor MC-MQS

The MC-MQS is a pin-hole quantum sensor for assessment of quantum flux density of the blue excitation light in the object plane. This sensor has the dimensions of a specimen slide. It features a 0.2 mm pin-hole with a fluorescing diffuser and a blue-enhanced photodiode. A separate preamplifier is provided, from which the signal is transferred to the PAM-CONTROL unit. In this way, the effective PAR-values in the object plane at different settings of measuring light and actinic light intensities can be measured, stored and applied for calculation of relative electron transport rates (ETR).