Freeze drying apparatus

A freeze drying or lyophilisation device comprises a chamber 1 having a temperature shelf 11 upon which one or more vials 7 containing a sample 8 may be located. A cold trap 13 and a means 19 to control the chamber pressure and control the shelf temperature FIG 2 43, 45 are provided. The chamber is fitted with a side window 3 to provide optical images of the chamber contents. The images may be obtained using microscopes 23, 51 employing darkfield illumination. Focussing 27 and translation movement means 29 may be provided for the microscopes, image sensors 30 may be supplied A second window 33 may be fitted to allow images in a vertical axis 9 to be seen. A manipulator 31 may be provided to move vials in the chamber. The device is intended for use in small batch research and development and may be bench or table top mounted. The microscope may be used to view movement of the sublimation front as the chamber cools.