LFA 467 HyperFlash

ZoomOptics for more Precise Measurement Results without Measurement Errors

Generally, the area on the sample’s upper surface being scanned by the detector is customized to fit to the maximum sample size up to 25.4 mm. Samples with a smaller diameter are most often covered with a mask or a cap to hide peripheral zones to the greatest extent possible. Since all bodies, however, emit infrared radiation – i.e., even the masking or capping material – the resulting detector signal is inevitably influenced. The extent to which this influence is noticeable depends on the difference in thermal diffusivity between the sample and the mask/cap material. The result – in the final segment of the main temperature rise – can be either a further continuous increase or a premature leveling of the detector signal. In either case, a shift of the evaluated half time occurs, thus falsifying the calculated thermal diffusivity.   

ZoomOptics (patent no.: DE 10 2012 106 955 B4  2014.04.03) allows the detector’s field of view to be adjusted until the only temperature increase registered is that of the sample and no influences by the surroundings or mask can have any effect. The pre-set focus value – which covers most applications – is 70%; however, this value can also be individually adjusted by the operator to the given sample geometry. 

The advantage of ZoomOptics is clearly illustrated by the following example measurement on Pyroceram:

for round and square specimens, liquids, pastes, polymer melts, resins and for measurements on liquid and powdery metallic samples