PCM-shielding of precision measuring equipment by means of latent heat

• Passive thermal shielding and cooling of sources of parasitic heat possible.
• Latent heat of phase change material (PCM) acts as heat sink.
• No vibrations are introduced to instrument by passive approach.
• Several hours of measuring time at thermally stable conditions.

Precision engineering and measuring instrumentation is always influenced by temperature or temperature changes. If these are caused by distinct heat sources, specific cooling approaches can be applied to optimise the thermal conditions. In this article a new passive cooling approach is presented, which enables a thermal shielding of a heat source and a homogenisation of a temperature distribution. The approach is based on the latent heat of melting of a Phase Change Material (PCM) which is used as a thermal buffer to the parasitic heat of a source. In the article, the approach is explained exemplary for of the Nanometer Comparator at Physikalisch Technische Bundesanstalt in Braunschweig. Here, the parasitic heat of a camera is absorbed by an Ga-Sn eutectic alloy during its solid-liquid phase transition. It is shown, that by means of this PCM-shielding a thermal stabilisation and homogenisation of a thermally and mechanically sensitive instrument can be achieved without adding any mechanical vibrations to it.