Lens info?

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Honk
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Lens info?

Postby Honk » Wed May 06, 2015 12:48 pm

I would like to find out if there is a lens, for my laser, that will increase the amount of distance my lens is in focus. I have it burning in a focus space of about 1/4 of an inch and if possible would like to increase this to 3/8 inch, or more. I see there are lens that are more expensive but would they add to the space in focus?
Thanks Jerry :?:

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Picengravertoo
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Re: Lens info?

Postby Picengravertoo » Wed May 06, 2015 4:00 pm

Hi Jerry,

I'm not sure about a different lens, but you may try increasing your focal height from your material and re-focusing your lens. It's worth trying.

Jeff

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Honk
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Re: Lens info?

Postby Honk » Thu May 07, 2015 12:06 am

Thanks Jeff
I'll give it a try.
Jerry

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Re: Lens info?

Postby Picengravertoo » Mon May 11, 2015 9:37 am

Hi Jerry,

I was reading on the J-Tech web site that a closer focal distance may be better, but they use a single G2 glass lens instead of a 3 element glass so I'm not sure if this is would work better for you or not. I have always used a 3" focal distance with either lens, but have not tried to do what you are with them.

http://jtechphotonics.com/?p=2602

They do sell there lens on there web site.

http://jtechphotonics.com/?product=high ... oated-lens

Jeff

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Re: Lens info?

Postby Honk » Tue May 12, 2015 2:21 pm

Hi Jeff
Thanks for the info. I did what you suggested about raising the laser diode and refocused the laser. It did make a difference in the area in focus. I have it running on a job right now and it is doing a lot better ( I think ). I am doing that same mountain lion picture again but I am engraving it using the depth map. I'll let you know when it is finished. By the way, I have the new linear bearing in and it seems to be about 103.457% better. I am going to try another 45 deg. burn soon. Some day I'll be able to do that fancy 45 stuff.
Thanks for the help
Jerry

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Honk
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Re: Lens info?

Postby Honk » Thu May 14, 2015 8:50 pm

Hi Jeff
I did change the focus height again as it did increase the focus area but I lost some of the gray shades. I lowered it past the old set area I had before and refocused the laser. I now have over 1/2 inch and it is burning the lion right now. It seems to be doing good. I'll put the picture on if it comes out.
Jerry

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Re: Lens info?

Postby Doug » Sun Aug 23, 2015 9:45 am

Jeff,
Best lens for either 2W or 3.5W diode? What are your recommendations for the best lens - single, 3-element, or G-2? Is there any noticeable difference? My use is mostly analog with a little vector burning. Jtech claims theirs is best. Have you done any testing on their lens?
Doug

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Re: Lens info?

Postby Picengravertoo » Sun Aug 23, 2015 2:14 pm

Hi Doug,

We have done allot of photo engravings with the J-Tech lens in there 2.8W laser kit, but the focused beam is not exactly round. We had it set at the 3" focal height. We always had to engrave only in one direction using the narrowest side of the focused beam. It may not make any difference with Vector burning. J-Tech also recommends a shorter focal distance then what we use, but we never tried that to compare any. They promote Vector cutting more so with there laser kits then photo engraving, so that may be why they recommend such a short focal height.

We tried a different single element lens recently and it appears to focus a little smaller then the J-Tech lens with the 6W Laser Diode we are 3D engraving with. This is at a 2" focal height because we are using an air assist we developed. The focal point size is not as critical as photo engraving, but we did notice a small increase in the feedrate we were able to set PEP5 at to get the same depth of cut in Poplar. This is because we were able to set a smaller size Pixel Resolution.

http://www.ebay.com/itm/261445531997?_t ... EBIDX%3AIT

Jeff

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Re: Lens info?

Postby Doug » Mon Aug 24, 2015 8:46 am

Thanks for the info. I have couple of the lens you recommended from ebay and was able to get focal point size down to between 0.004 and 0.005 with mostly round point. The 2W works fine for vector engraving and cutting photo paper. Just have to slow down speed and with cutting paper do two passes. How does the 3-element and G-2 lens compare to the single? Know they cost more, but are there any benefits or negatives?

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Re: Lens info?

Postby Picengravertoo » Mon Aug 24, 2015 9:57 am

The beam shape is smaller with the 2-3W LD then the 3.5-6W. The single element glass lets more light through then the 3-element glass does, so you will get more burning power with it. We have not tested a G2 in a long time, but when we did, it would not focus good enough to engrave photos.

We also have not done any photo engraving tests with the 2-3W LD and the single element lens from ebay yet either.


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