The present invention relates to devices and method for melting solid polarised sample while retaining a high level of polarisation. In an embodiment of the present invention a sample is polarised in a sample-retaining cup 9 in a strong magnetic field in a polarising means 3a, 3b, 3c in a cryostat 2 and then melted inside the cryostat 2 by melting means such as a laser 8 connected by an optical fibre 4 to the interior of the cryostat.