Hi people :) I want to build an interferometer. In the course of looking for a suitable light source for my instrument I have been advised to check the 'coherence distance' of the sources; it is clear to me that this distance places practical limits on the design of the machine. However 'coherence distance' is not mentioned on the company data sheets for the devices I have been looking at. I need to find a light source that I can afford, with as short a wavelngth as possible and a coherence distance of at least 5mm. Can anyone help me please?