Author Topic: Rectangular laser beam fix (At least for me). Updated with Pics.  (Read 355 times)

bnaivar

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Recently, I purchased a 5500mW laser module off of EBay.  As I was waiting on the slow boat from China I happened to mention it to a friend that also does laser engraving.  He told me that he had heard the 5 watt laser modules only project a rectangular beam.  Sadly, he was right.  The beam from this module was very large and rectangular even when focused as tightly as possible.  The only solutions I could find were to either tilt the module 45 degrees so that the kerf of the beam wasn't as wide, or to use tape to cover up part of the lens.  Neither of these solutions worked well. 

I took the lens off of the module and noticed that the laser diode was an open type diode with no metal can on the top of the emitter.  I wondered if this was why the beam was rectangular instead of circular like the diodes that have only a small opening at the top. 

I took a plastic washer and placed it over the diode, and then a metal washer on top of that.  EUREKA! I now have a laser module with a circular beam that I can focus to a tight point, with no loss of power that I can detect. 

The red circle is the size of the beam before the modifications.
« Last Edit: July 23, 2018, 05:08:11 PM by bnaivar »

Rebelturtle

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Re: Rectangular laser beam fix (At least for me). Updated with Pics.
« Reply #1 on: February 10, 2019, 01:30:56 PM »
Is the last pic with the Sharpie in it, the burn pattern before you put the washers in?  vs the gray scale image is after?
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ggallant571

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Re: Rectangular laser beam fix (At least for me). Updated with Pics.
« Reply #2 on: February 10, 2019, 01:53:23 PM »
If you are blocking the light at the source you must be loosing energy. Perhaps you are getting enough to accomplish the task. Getting the kerf small is very desirable. I replaced the lens on my 5.5W with G2. Has a shorter focal length and better beam pattern.

Have since replaced the 5.5W with a 15W which I don't care for as the kerf is very wide. Perhaps the washer will help. What are the diameters of the holes in the washers?

1.6W gives the BEST dot!!!
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Zax

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Re: Rectangular laser beam fix (At least for me). Updated with Pics.
« Reply #3 on: February 10, 2019, 03:04:09 PM »
It looks like you are getting good results, that grey scale test looks impressive. I would expect some power loss but perhaps not significant since most of the energy is centered.