DIY Beam Expander.

[steve001]

Re: dioptika beam expander?

Laser Beam expanders are designed to decrease the laser's beam spot size at large distances. There are two main types of beam expanders: Keplerian and Galilean. In its simplest form, the Galilean type consists of a positive and a negative focal length lens whereas the Keplerian type consists of two positive focal length lenses. Both designs provide a certain angular magnification, called the Expander Power. The beam diameter is first increased in size by this power and then the beam divergence is reduced by the same power. This combination yields a beam that is not only larger, but one that is also highly collimated. The result is a smaller beam at a large distance when compared to the laser alone (Equation 1.0).
Technical Support - Edmund Optics
Your first drawing is a Keperian beam expander. The drawing is mislabeled.
The above drawing is a Galilean type expander. It can use only two lenses and work work just fine.
.

 

[HIMNL9]

Re: dioptika beam expander?

Damn, i confused the names in the draw and then, referring to the draws, messed up also the rest, you're right ..... sorry for that.

The one i tried is the keplerian, with 2 identical positive lenses.

trying to clarify, basically, that what i want to say in the previous posts, is that with the configuration that use the identical lenses, you can not just expand the beam, but also shrink it, for a better (smaller) dot at long distance, with still the beam compact (low divergence)

True, not too much, considering that the beam is already small, but til a certain point, it works

 

[steve001]

Re: dioptika beam expander?

No you don't shrink the beam diameter for lower divergence. You must expand the beam make it wider that will give you lower divergence for a smaller spot size

 

[Glutton]

Re: dioptika beam expander?

I can't tell ya how long i've been sitting here looking at you avatar, trying to replicate it with my own two hands

Yeah a lot of people keep telling me that it is hypnotizing. I have been staring at it since I found it and I still cant do it.



Ok so I'm gonna try to build a Galilean type expander after I do some research. I'm new to optics so I'm gonna need to do sum lernin

Do I have to design the expander to compliment one specific laser diameter and divergence, or can one be universal for several laser beam specs.

From what the pictures appear to show of the Galilean type is that the FL of the two lenses don't need to be identical and I would just have to calculate the beams diameter after the diverging lens and get a large enough diameter PCX lens to catch the beam, correct? Can the PCX be alot larger than the beams diameter after it is spread (that way I can just change the PCV lenses the get different expansions ratios)?

Also, how does moving the two lenses closer and further change the focus of the beam?

If you don't want to spoon feed me answers I understand. I will do my own research before I attempt this anyway and will probably answer all these questions along the way.

 

[Shogoki]

Re: dioptika beam expander?

Yeah a lot of people keep telling me that it is hypnotizing. I have been staring at it since I found it and I still cant do it.

totally going more off-topic..

but here's a website dedicated to exercising and getting dexterity in your hands
Finger Fitness Warmup Video | HandHealth
check out the instructional video for the hand wave

yea.. i saw your avatar and pretty much was psshhh.. Greg Irwin (the guy who owns the site i linked...) can do some crazy stuff..

after the warmup videos.. check out the other ones.. not many people can separate movement between their pinky and ring finger..

 

[themandalorian]

Re: dioptika beam expander?

Just to let you guys know, CNI sells a 5x for 50 and a 10x for 100 for their PGL III series. Don't know if it will fit other lasers

 

[steve001]

Re: dioptika beam expander?

Yeah a lot of people keep telling me that it is hypnotizing. I have been staring at it since I found it and I still cant do it.



Ok so I'm gonna try to build a Galilean type expander after I do some research. I'm new to optics so I'm gonna need to do sum lernin

Do I have to design the expander to compliment one specific laser diameter and divergence, or can one be universal for several laser beam specs.
Just make sure the beam exiting the laser is smaller than the diverging lens by 1 mm to avoid internal reflection should a too wide beam hit the lens edge

From what the pictures appear to show of the Galilean type is that the FL of the two lenses don't need to be identical and I would just have to calculate the beams diameter after the diverging lens and get a large enough diameter PCX lens to catch the beam, correct? Can the PCX be alot larger than the beams diameter after it is spread (that way I can just change the PCV lenses the get different expansions ratios)?
Two lenses with the same FL will give you a beam diameter the same as it is originally. You need two lenses of different FL's. Yes you will need a PCX lens larger than the expanded beams diameter. A larger PCX diameter is a good idea. It's best to buy the minimum fl PCV lens you can find which appears to worldwide be -6mm. A very few sites carry off the shelf PCV and DCV lenses but they are foreign make usually not AR coated. I saw one list on the Melle Griot site -5 mm, but not AR coated . Since that is the case swapping the PCX for a longer focal length PCX is much easier. More to choose from. Try out the applet I linked to earlier. BTW, there's no reason you can't use two PCV lenses stacked or spaced apart to mimic a lower negative FL PCV lens.
Try the applet I linked to for determining beam divergence. One more thing divide the the positive len FL by the negative lens FL will tell you the expansion ratio. 36/6 will give you a 6x beam expander for example


Also, how does moving the two lenses closer and further change the focus of the beam?
Either focuses the beam or spreads the beam

If you don't want to spoon feed me answers I understand. I will do my own research before I attempt this anyway and will probably answer all these questions along the way.

P.S. Try out the applet I linked to earlier.

 

[Glutton]

Re: dioptika beam expander?

P.S. Try out the applet I linked to earlier.

In the applet what is separation length? Should the separation length for the first surface be 0?


The separation for the first surface is the distance of the lens from the laser source isnt it?

Then the second separation is the PCV from the PCX right? so then all I have to do is mess with the separation lengths to find the ideal mRad which will give me the beams diameter so that I know what diameter of PCX lens required which should be about a mm larger than the beams colimated diameter?

With a PCV lens of -6, I should input -6 into the first lens FL, correct?

 

[Glutton]

Re: dioptika beam expander?

If I am using the applet correct, I can use a PCV -6, with a PCX 125, and achieve a 20x expansion with a 2mm laser diameter (used a large diameter to overcompensate for other beam use) and have an exit diameter of about 42 mm and housing length of about 119-130mm.

So a 50mm diameter PCX will do fine. With the total lens cost about 70-85 USD (housing excluded) all the while have a transmission efficiency of 98.4% (425nm-675nm)

This is going to be a hella fun project!!!

Just one question...

What is the difference between "inked" vs "coating"?

 

[steve001]

Re: dioptika beam expander?

If I am using the applet correct, I can use a PCV -6, with a PCX 125, and achieve a 20x expansion with a 2mm laser diameter (used a large diameter to overcompensate for other beam use) and have an exit diameter of about 42 mm and housing length of about 119-130mm.

So a 50mm diameter PCX will do fine. With the total lens cost about 70-85 USD (housing excluded) all the while have a transmission efficiency of 98.4% (425nm-675nm)

This is going to be a hella fun project!!!

Just one question...

Correct. I played with the numbers too yes that will work. With a beam diameter of 2mm your Rayleigh Range (RR) is 2373.32 feet. That means the beam will expand 1.4 times it's exit diameter at that distance the beam diameter is 5.74 cm or 2.259 inches

What is the difference between "inked" vs "coating"?

Inked means the edges of the lens are blacken to minimize internal reflection. AR mean Anti Reflective coating an explanation can be found on the Edmund Optics site.
for the fun of it add a second -6 lens . First stacked. Then spaced apart. Notice how the RR increases.

 

[Krutz]

Re: dioptika beam expander?

i guess "inked" means they blackened the side of the lens, to keep internal reflections and artifacts even lower.. they do that (melles griot), but perhaps it means something totally different in your context.

manuel

 

[Glutton]

Re: dioptika beam expander?

If the lenses are designed for 0* angle, is the 0.4% reflectance still accurate for the PCX receiving the FL of the PCV, or will the reflectance increase, and my figure of 98.4% transmission become inaccurate?

 

[steve001]

Re: dioptika beam expander?

If the lenses are designed for 0* angle, is the 0.4% reflectance still accurate for the PCX receiving the FL of the PCV, or will the reflectance increase, and my figure of 98.4% transmission become inaccurate?

For product questions like this call then toll free and request their free catalog. This catalog contains a lot of technical info. Also you can click here to see the same info using interactive online catolog.
Optical Components Catalog Edmund Optics

P.S. When you used the applet did your browser show the graphical presentation below all the boxes with numbers ?

 

[Glutton]

Re: dioptika beam expander?

For product questions like this call then toll free and request their free catalog. This catalog contains a lot of technical info. Also you can click here to see the same info using interactive online catolog.
Optical Components Catalog Edmund Optics

P.S. When you used the applet did your browser show the graphical presentation below all the boxes with numbers ?

no it did not, flash player eh?

 

[steve001]

Re: dioptika beam expander?

no it did not, flash player eh?

It could be flash dunno. It works with Internet Explorer not with Firefox. It might work with other browsers. It will show graphically what the beam is doing as it passes through the lenses.

 

[HIMNL9]

Re: dioptika beam expander?

Oh, then is for that that for me is not working at all ..... no explorer here, only firefox with noscript and adblock plus (and some other tricks :eg