I am doing some imaging experiments for which I am using the cellphone camera and flash (LED). However, very little amount of light is produced to illuminate the object, which is place at a distance
Hi, Rubdra As you pointed out the distance x from the illuminator to the optical axis of the camera objective lens should be close enough to obtain high illuminance on the object, particularly when the object distance z is short, because the illuminance is proportional to cos(theta)^3/z^2, where tan(theta)=x/z and z=20mm in your case. Actually at x=z, relative illuminance E is 35% while E is rapidly reduced to 9% at x=2 z,. Since the inner diameter of Olympus Ring illuminator, Light Guide LG-1 is about 40mm, theta at z=20mm is approximately is the first case. The diameter of cell phone ring light looks like a bit larger because it is supposed to take self-portrait, implying the object distance is an arm’s reach. Shigeo
Hi Rudra
i believe you can use a High NA large core fiber as a LED light guide.
you can either pigtail it to the cellphone (not recommneded if you use it on a daily basis...) or try to use a collimator to collect as much light as possbile into the fiber
Arie
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