My powerful LED spotlight has a highly focused beam and I would like to make it more like a floodlight by changing the reflector (or however). Hopefully the light can be projected as a uniform spot at roughly 20° or 25°. Any experiences, ideas, or references would be appreciated.
The basic idea is to move the LED away from the focal point of the beam focussing device (whether lens or parabolic reflector). When the LED is at its focus, all rays from the LED are projected as parallel straight lines in front of it. You can spread out the beam by moving the LED off-focus.
You can also place a diffuser in front of the reflector, as is done with car headlights, to scatter the focussed beam.
If it's a small flashlight/torch stick some crumpled Al foil around the the reflector to de-focus it. A f/ight is hardly a precise scientific device. If the bulb cannot be relocated easily bend or deform the reflector to get a 'patchy' reflection of the light from it. It's rather ironic that an LED famed for its small brilliant (point source) of light is not doing the job since the OP needs a more 'floodlight' or broadly spread light!
Incandescent bulbs send light in all directions (well, except for the socket side), so a reflector helps to narrow that, and direct it in the direction you want.
An LED puts the light in a fairly concentrated area to begin with. A=20 reflector is less likely to be useful, because there's not much incidental= =20 light to redirect.
I'm assuming one reason for multiple LEDs is to make the beam of light wider.
I suspect the way to change things is to have the LEDs aimed at the=20 reflector and then the reflector can spread the light coming straight on from the LEDs (and the only light from the LEDs) into a wider angle.