problem

[WN89]

just received a blue violet laser in the post today, its only a cheap ebay one claiming to be 1mw so i wasnt expecting anything great but other than producing a dot when i shine it its more of a messy blob of purple light, i mean theres a dot in the middle but its surrounded by squigly lines of light making like a like a giant blob of light on the wall, its not too bad close up but at around 6 foot or longer it looks really messy. i tried to get a picture but my camera will not show it. ive taken the silver cap off the end and tryed to clean the lens but this has not helped. i dont know if it would make a difference but compared to my 50mw green the lens is very far down the aperture, theres a big space between the lens and the end of the laser. any advice of how i could fix this "blob" would be much appreciated. this is my first 405nm so i dont know if this is a common problem with cheap ones of this wavelength and if anyone else has experienced this?. thanks in advance for any advice.

ps: before anyone tells me to use the search bar i already have done and have come back with no useful information.

 

[WN89]

ive tested the laser outside now its dark and it has become clear this laser has terrible divergance. at about 20ft or so the dot is HUGE so i guess the answer im looking for is; is there a way i can adjust the lens on this to make the dot smaller? its just a regular new wish style pen. it cost me peanuts so im not worried about the risk of breaking it really. cost me like £4.85 (around $10). thanks again.

 

[Sigurthr]

The end cap is pressed on with hydraulics, you can remove it with pliers or vice grips by wiggling it off. Then just carefully use a very wide and thin flat screwdriver or similar object to turn the lens (there are slots for a spanner wrench just a millimeter above the lens surface).

 

[WN89]

thanks Sigurthr i have already got the cap off, ive read a lot of things about the cap being near impossible to get off but mine just popped off. sweet im gonna give that a go right now. thanks for the reply.

 

[daguin]

Before you do anything, have someone else shine the laser at a wall about 20 feet away.

You be down at that wall to look at the dot.

450nm light is notoriously hard for our eyes to focus on

Beyond that, it is perfectly normal for the lens to be closer to the 405nm diode than it is to the crystal on a green DPSS module

Peace,
dave

 

[WN89]

just tryed your idea daguin and the light still looked a mess, i also tryed sigs idea and has made no difference to the divergance on the laser. i think i just gotta crap laser lol o well for the price i paid im not too fussed really. il just spend a little more money on my next 405nm. thanks guys.

 

[Sigurthr]

Are you sure the lens was moving? If you were able to rotate the lens it should have dramatic effects on divergence. Unless you mean to say that it did move and it made huge changes but you couldn't find a spot with better divergence than where it was when you got it - that is entirely possible.

 

[WN89]

hey sig, yeah i think it is already as bang on as its going to get, i turned it left and it made the dot even bigger, the same also happened when i turned it right. i think it must just be a poor lens which was kinda expected as it was so cheap, still fun to play with indoors as its my first 405nm so im enjoying the colour but it just has no distance on it really, still getting a lot more fun from my green 50. thanks for the advice man.

 

[Lase]

When you turn the lens are you trying to make the dot small at a close range? <6ft away?

To get better divergence you should try focusing it to a spot further away.

Lase

 

[Sigurthr]

I think what may have happened is they never press-fit the diode all the way into the module. If the diode is only flush, and not past flush, you'll never get the lens to focus it right, no matter what lens you use.

 

[WN89]

hey lase, yh thats what i have tryed to do also and has made no difference, i have tryed it close up and from distance. i think that it was already at its optimum point.
i think your right sig its just NOT going to focus any better. will just have to make do with how it is now until i get a better violet. still got my greenie to play with so alls good