The study of the influence of various reflectors and diffusers on the shape of the light beam

I am a cyclist. When you drive on public roads, you realize that there is not a lot of light, and once again I sat down to read forums and articles in order to buy something else good for myself on the steering wheel and on the helmet. Among other things, I caught sight of an article by a comrade known in cycling circles, in which he recommended simple and cheap Chinese lanterns as a universal remedy - they can be used both independently and as a bicycle lamp, and also in a bunch of different situations. One thing is bad - for different purposes a different shape of the light beam is necessary.

This model of flashlights is a kind of designer, to which the manufacturer supplies various types of reflectors and diffusers, so I ordered everything that was in stock, waited for delivery, and started testing.

So, I had:
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• 4 identical flashlights. The package included smooth parabolic reflectors and plain flat glass as a diffuser.
• Orange peel reflectors are parabolic, but not smooth, but provided with small, 0.5-1 mm, irregularities across the entire inner surface.
  
  
  
• Diffusers in stock:
  
  
  
  
  • Smooth (no photo)
  • Small (0.5 mm) hexagonal cells
  • Parallel edges of a triangular profile
  • Large (1 mm) hexagonal cells
  • Also large cells, as the previous paragraph. At first I decided that I put two identical ones - but it turned out that they give completely different light spots. after careful consideration it became clear that they have different forms of internal recesses at the radiator:
    
    
    

So, it turned out 12 options for combinations of reflectors and diffusers. I photographed the light beam that forms from each combination, and formed a pivot table:



Based on these images, we can draw the following conclusions:

1. The best point source (as a search lamp) is formed with a combination of a smooth parabolic reflector and without a diffuser.
2. Paradoxically, the use of an orange peel reflector has almost no effect on the light beam. Compared with the type of diffuser, its influence is minimal.
3. The use of an orange peel reflector without a diffuser increases the angular size of the central beam by about 1.5 times.
4. The most smoothly growing beam (with intensity increasing towards the center, approximately according to the Gaussian law) is obtained by combining an orange-peel reflector and a large-mesh diffuser. Reflector makes the distribution a little smoother. Such a bundle is suitable, for example, for attaching to a helmet for night skiing in the forest.
5. A wide beam of uniform intensity did not turn out for any combination, but closest to it was a smooth diffuser with a smooth reflector. In the center, with such a combination, artifacts similar to the form of a radiating crystal are observed.
6. And, finally, the most interesting result is obtained when combining the orange peel reflector and the ribbed diffuser. Such a combination allows one to obtain a beam expanded in one plane. Such light is ideally suited as a bicycle headlight, as it will allow to illuminate a fairly wide angle and not dazzle oncoming pedestrians and drivers of other vehicles, which, given the very serious power of this flashlight, is an actual problem.