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Last season, use of the camera flashlight was explicitly allowed: https://ftcforum.usfirst.org/forum/i...system-answers. It was very helpful for illuminating the jewels for evaluation with CV. This season, until now, we had been using the flashlight to illuminate the minerals.
Use of the flashlight this season has now been disallowed, on grounds that the beam is focused and directed. In searching for a substitute light source, I've learned (https://www.ledsupply.com/blog/led-optics-explained/) that essentially all LEDs have a clear (or colored) plastic encasement (also referred to as the primary optic) that serves not only to protect the semiconductor, but also to "shape" the beam. For many of them, available specs include a viewing angle (angle from the center to edge of useful beam). Datasheets are available for some, demonstrating the actual distribution of illumination. Several examples are as follows:
https://www.jameco.com/z/LWK3333-Whi...-4_334502.html (white LED with viewing angle of 16 degrees);
https://www.jameco.com/z/UT5HW3-4D-U...s_2115493.html (white LED with viewing angle of 30 degrees);
https://www.amazon.com/DiCUNO-1000pc...18&ref=sr_1_18 (kit of LEDs with viewing angle of 30 degrees).
The above are all innocuous-looking little LEDs which, before today, I would never have suspected were focused.
I'm not equipped to do quantitative testing but I did do a subjective evaluation of the beam angle of the flashlight on my Moto G5. This involved placing the camera on a piece of paper on a table with flashlight on, beam centered on a point on the wall, then rotating around the light source to the left, then the right, until the beam edge was almost to that point. At each position, the camera was used as a straight edge to draw a line on the paper. The angle between the two lines was 60 degrees, so the approximate viewing angle is 30 degrees. That makes sense, as the camera FOV is about 60 degrees. So it doesn't appear that the camera flashlight is any more focused than many LEDs that one might expect to find on an FTC robot.
It would be helpful to have more specific guidance on what constitutes an illegally focused beam; is there some minimum allowed viewing angle?
Use of the flashlight this season has now been disallowed, on grounds that the beam is focused and directed. In searching for a substitute light source, I've learned (https://www.ledsupply.com/blog/led-optics-explained/) that essentially all LEDs have a clear (or colored) plastic encasement (also referred to as the primary optic) that serves not only to protect the semiconductor, but also to "shape" the beam. For many of them, available specs include a viewing angle (angle from the center to edge of useful beam). Datasheets are available for some, demonstrating the actual distribution of illumination. Several examples are as follows:
https://www.jameco.com/z/LWK3333-Whi...-4_334502.html (white LED with viewing angle of 16 degrees);
https://www.jameco.com/z/UT5HW3-4D-U...s_2115493.html (white LED with viewing angle of 30 degrees);
https://www.amazon.com/DiCUNO-1000pc...18&ref=sr_1_18 (kit of LEDs with viewing angle of 30 degrees).
The above are all innocuous-looking little LEDs which, before today, I would never have suspected were focused.
I'm not equipped to do quantitative testing but I did do a subjective evaluation of the beam angle of the flashlight on my Moto G5. This involved placing the camera on a piece of paper on a table with flashlight on, beam centered on a point on the wall, then rotating around the light source to the left, then the right, until the beam edge was almost to that point. At each position, the camera was used as a straight edge to draw a line on the paper. The angle between the two lines was 60 degrees, so the approximate viewing angle is 30 degrees. That makes sense, as the camera FOV is about 60 degrees. So it doesn't appear that the camera flashlight is any more focused than many LEDs that one might expect to find on an FTC robot.
It would be helpful to have more specific guidance on what constitutes an illegally focused beam; is there some minimum allowed viewing angle?
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