The LED is RED so of course it is 2.0V, not 3.5V like a blue or white LED.
They take an ordinary LED and stick it in a tightly focussed case. Its beam is only 6 degrees or 12 degrees because both numbers are spec'd. The graph shows 10 degrees.
If it is not pointing directly at you then you might not see it. I like wide angle bright LEDs.
The LED is RED so of course it is 2.0V, not 3.5V like a blue or white LED.
They take an ordinary LED and stick it in a tightly focussed case. Its beam is only 6 degrees or 12 degrees because both numbers are spec'd. The graph shows 10 degrees.
If it is not pointing directly at you then you might not see it. I like wide angle bright LEDs.
A little laser pointer is extremely bright because all of its energy is focused into a very narrow beam. But it isn't focused, it is coherent.
The Chinese LED also concentrates all of its energy into a very narrow beam.
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function (a standardized model of the sensitivity of the human eye to different wavelengths, also known as the luminous efficiency function).
So, if one was to use a certain LED package shape, its more than possible, but not always practical for most 5mm/10mm LED applicaitons (panel indicators). Note the angle of those LED's (as audioguru pointed out). 6 degrees! treble that angle (as many high brightness LED's are 20 degree's), and at the same distance the area of illumination would be NINE times larger. So its intensity would be 9 times smaller, or 7-8000mcd. Thats a common figure for 20 degree LED's. Converting mcd to Lumens wouldn't be useful, because the emitted light isn't lambertian, more like a ring/halo of light, with artifacts, not so bright in the middle.
So at 20ma, yeah I would say might be possible, just not a very practical angle (except beam breakers or perhaps light communications). The 'mcd' of an LED is generally misleading, and can be a dreadful indication of brightness unless one checks the angle. If you epoxy a clear LED into acrylic, the lens-air interface pretty much disappears but the so called 'high brightness' ones still seem to kick out a fair bit of light.
Yes, as others have pointed out, if the light is focused it can be be much brighter. Some manufacturers provide data on the beam pattern so you can investigate how much is going in what direction in front of the LED by checking out the data sheet.
Tight (narrow) beams are good for longer distances but not very good for close up work unless the area to be viewed is small. The narrow beam can also be good for indicator lamps.
Cooling is no problem, they will be underwater. I have found some 10w 600 lumen leds, 10 of these should put me roughly where i need to be. just gotta figure out how to spread all that light around
That is the problem with my project right now. Not getting the brightness I need.
I am using 20K mcd LEDS. 5mm driven directly from 220V @ 20Ma.
24 of them driven with a very simple reliable circuit. The high power LED'S want a minimum of 350 Ma. My simple /cheap/reliable PSU can only accommodate around 30 Ma. So basically..I am (swearing removed). Damn.
A 100W LED that operates at 32V is simply made from ten 3.2V/10W LEDs in series or from forty 3.2V/2.5W LEDs in series-parallel.
Here is a cheap little 4W LED light bulb that makes a very narrow beam of light: