Well, i had an idea for a cheap, easy to produce and efficent beamdump (uhm, maybe i have to patent it, before post it publicly .....
)
It can be produced also without access to machines, at least until 12mm diameter input aperture, and if someone have access to machines, it can also be produced more "professionally" in bigger sizes, with the same system and, basically, with the same efficence.
For "homemade" production, is enough a drill (a column drill, or also a drill that can be placed in a vice for "emulate" a lathe
p), and a file ..... get a piece of 12mm threaded bar, the ones with the bigger size threads you can find, and a corresponding 12mm "long joint" bolt (they are usually used for join two threaded bars and some shops have also 60 or 80 mm long ones) ..... place the threaded bar piece in the drill, and file one side in conic shape (always paying attention to safety !!) ..... if you have steady hands and a good rest point, you can obtain a decent regular and symmetrical shape (anyway the conical part must be long at least 20 or 25mm, longer it is, better it is), and refine it with a fine file or sandpaper ..... at this point, simply screw it in the long bolt (you can paint it and the inside of the bolt flat black before or after, as you prefer), et voila', high efficent homemade beamdump.
Let me post a draw, so it's more clear:
The cone diffuse the light on the threads inside the bolt, that also prevent the back reflections very well.
Those that have access to some machines can also made them more efficents and "professionals", using internal diameters bigger than 12mm ..... about this diameter, i choosed the 12mm dia threaded bar just cause here the 99% of the drills that you can find around don't take more than this diameter, and the "long bolts" can be found reasonably easily in hardware shops, but with a real lathe, this can be done on any diameter that the lathe can hold, and also the bolts can be substituted with tubes, threaded with the corresponding thread measure of the bar you made
The inside threaded surface have the same efficence of a "professional" waved surface (once you painted it flat black, ofcourse
), but the advantage is that it can be made much more easily with a lathe with threading function, or also just with a tap, if the lathe don't have that function ..... also, it don't need to be a precise threading long all the tube, cause once you are able to screw some millimeters of the bar in one of the sides of the bolt or tube, the rest can also be a wrong or defective thread, it only need to trap and scatter the light after all :na:
BTW, if someone start to produce them industrially, i want my part of the royalties, ok ? :eg: ..... (j/k
:crackup
