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TechTalk_2

Cuvette Rotation and Translation Unit

This unit allows the measurement of non ergodic samples such as gels, which, due to their non ergodic behaviour, can not be measured using a standard goniometric setup. The idea is, that by using truning and up/down movement different specles of the sample can be measured and, provided enough such independent specles were measured, am ensemble average of the sample’s scattering behaviour is reassembled. To do so, two independent movements of the cuvette are featured, either a stepwise or continuous rotation at variable speed and/or an stepwise or continuous up/down movement of the cuvette at variable speed. Both movements can of course be coupled.

The use of special, high precision, ball bearings ensures high reproducablity in both, rotation and up/down movement. Two DC-motors with gear allow variable speeds over a wide range, without the unavoidable “distortions” a stepper motor would introduce.

The ALV-Correlator Software for WINDOWS has full in-built support for this unit.

Depolarized Light Scattering

Allows the measurement of the depolarized component of the light scattered by the sample. Consists of two special prism,

  • A Glan prism to enhance the polarization ratio of the primary laser beam to better 1:105, interferometric quality and ML-coated.
  • A Glan-Thomson prism as analyzor in front of the optical detection system, interferometric quality and ML-coated. Angular offset < 2 seconds of arc.

Both prism are supplied with appropriately adjustable stand, the Glan prism stand allows X/Y and tilt/turn adjustment, the Glan-Thomson prism is mounted in a special rotation holder which allows analyzor plane rotation whithout loosing the adjustment of the optical detection.

High Temperature Cell Housing Model 2000 (-12°C ... +140°C)

 Extents the temperature range of the ALV-Compact Goniometer Systems to   -12°C ... +140°C. Instead of using aluminum as cell housing material, the material is replaced by a special epoxy / glass fiber compound at all such locations either being exposed to the user or require high thermal stability. The advantages of this special material are manyfold, the most important are

  • it offers high insulation coupled with extremely low heat conduction (touch-safe up to very high temperatures)
  • it offers near to zero heat expansion

As a result, the High Temperature Cell Housing does not require any additional adjustments with the temperature changes - not only would such adjustments be very complicated due to the high temperature - they are simply not required. In addition, a special heat exchanger design ensures almost gradient free temperature distribution within the sample, even at the max. temperature. As heat exchanger fluid, water can be used. For temperature well above 90°C, either special water-glycol mixtures or special heat exchanger fluids must be used instead. Sillicon oil as heat exchanger fluid should never be used, due to the potential contamination problem on  the glassware (e.g. the index matching vat and the cuvettes)
 

Glassware and Cuvette Holders

Special cuvette holders are available as option. Cuvette holders for cylindrical cuvettes can be manufactured with a max.  inner diameter of 27,2 mm. A cuvette holder for square cuvettes with the industry standard 12,5 x 12,5 mm outer dimension is available as option.

A wide range of 10 mm and 20 mm glass and quartz glass cuvettes is available as option.