Help! Something wrong with my aspheric lens

[WeatherB]

Hi - My aspheric lens is not creating a nice circular light pattern and produces two additional rings.

I am using the "JAEGERS 41MM DIAMETER ASPHERIC LENS, 35MM FL" from Surpluss Shed (http://www.surplusshed.com/pages/item/l3953.html).

Is this caused by a poor quality lens? The areas in question are highlighted in red on the picture below.

 

[Roland Gama]

Looks like the rings are caused from light reflected off the bezel if its a shiny one.
Try using black tape on the internal side of the bezel to ascertain the cause.

 

[WeatherB]

Looks like the rings are caused from light reflected off the bezel if its a shiny one.
Try using black tape on the internal side of the bezel to ascertain the cause.

That's a good guess. But my bezel is black and even the black tape trick didn't help.

 

[Nos]

the inner ring might come from the led, if you are using a xr-e it can be reflections from the ring of the emitter :candle:

not sure about the second ....

 

[AlexGT]

He he he! I noticed that before this is what is happening, check the aspheric while turned on from the side, you will see that the upper most part of the aspheric glass is reflecting the beam towards the side. I don't see any way of fixing it but the reflection is not too bright.

AlexGT

 

[Alan B]

Did you remove the reflector?

Can you focus the beam to see the LED die on the pattern?

I like the round pattern better, but greatest brightness occurs when the LED is visible in the projected beam.

 

[AlexGT]

Here, it is perfectly normal

Mag Aspheric



Lumapower M1 aspheric



Both have it!, it is just a reflection from the top of the glass projected towards the side.

AlexGT

 

[WeatherB]

Did you remove the reflector?

Can you focus the beam to see the LED die on the pattern?

I like the round pattern better, but greatest brightness occurs when the LED is visible in the projected beam.

The shots that I provided was with the lens fully focused so you can see the die. You just don't see them in the picture since I focused it on a wall about 2 meters away.

Here, it is perfectly normal

Mag Aspheric



Lumapower M1 aspheric



Both have it!, it is just a reflection from the top of the glass projected towards the side.

AlexGT

Interesting, looks like I was asking for too much. Good to know that my lens isn't defective or something.

 

[LukeA]

Did you remove the reflector?

Can you focus the beam to see the LED die on the pattern?

I like the round pattern better, but greatest brightness occurs when the LED is visible in the projected beam.

Not true. The LED dome collects more light from the die than the aspheric lens so focusing the aspheric on the dome gives higher brightness and puts more light downrange than focusing the lens on the die.

 

[collector]

My aspheric lights also produce 2 rings, I think that one of the lens characteristics...

 

[Gunner12]

Most 5mm LEDs, which also uses a built in lens, also have the ring, so it's normal. I think it's caused by internal reflection in the lens(only a guess).

An AR coated lens might make the rings much less visible.