Quote:
Originally Posted by Canis Vulpes
.......... I am thinking multimode light would quickly diminish leaving only a singlemode beam if the length is beyond a critical dimension for this to occur. Critical length depends on diameter of tube and with a party straw this length is achieved as their length must be 40 times their diameter( approx 5mm dia and 200mm length). If the critical length ratio is 40:1 then my 80mm diameter snoot would need to be 3.2m  to give the same result as one party straw. |
Educated under a flat top thorn tree on the plains of Africa, so that lot has gone right over my head.
Don