Hi, In studying about lasers, it was mentioned that lasers are highly focusable, and this was because of the high spatial coherence of lasers. Just want to ask: 1. Why and how does spatial coherence affect focusability? 2. How is a laser typically focused (using a lens?) 3. Why do lasers have a high spatial coherence? I know that lasers have high temporal coherence because stimulated emission produces identical photons (thus they all have the same wavelength). But I'm not too sure why that results in spatial coherence. Thanks in advance.