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Best lens for Collimation ?

Ved

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Which lens should i buy for normal collimation of light ? Will biconvex aspherical lens do it ?
 



steve001

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Which lens should i buy for normal collimation of light ? Will biconvex aspherical lens do it ?
Yes. But what is your goal? A biconvex aspherical is know as a Best form lens.
 
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paul1598419

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Most aspheric lenses we use are plano-convex. There are many different lenses used to collimate laser light and which one(s) you use depends on the diode, if it is a direct diode laser. Some have such aggressive divergence in one axis that cylindrical lenses are used in conjunction with an aspheric lens. Other times we use compound lenses or multi-element lenses to collimate a diverging beam.
 
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Ved

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Most aspheric lenses we use are plano-convex. There are many different lenses used to collimate laser light and which one(s) you use depends on the diode, if it is a direct diode laser. Some have such aggressive divergence in one axis that cylindrical lenses are used in conjunction with an asspheric lens. Other times we use compound lenses or multi-element lenses to collimate a diverging beam.

I get that ,one question guys does the wavelength of light affects the collimation ? Cause i found a site saying Lens for 532 nm what if use higher or lower wavelength light?
 
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paul1598419

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Mostly because of the anti-reflective coating on the lenses, also known as AR. If the laser is truly monochromatic.... and not all are, it makes little difference in the lens itself.
 

Ved

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So if want to collimate a led shoud i buy 532nm lens?
 

paul1598419

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You aren't going to collimate an LED with any lens. They aren't coherent. They are generally across a wider band too. A 532nm lens might be AR coated for that wavelength.
 

Ved

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You aren't going to collimate an LED with any lens. They aren't coherent. They are generally across a wider band too. A 532nm lens might be AR coated for that wavelength.
Which light source should i'll be using?
 

Alaskan

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Steve, your mention of biconvex aspherical caught my attention, a ~6 mm G2 lens is a slightly biconvex aspherical, I am sure for a good reason. However, for larger diameter lenses I keep finding plano convex aspherical lenses being shown as an ideal, do you know why biconvex aspherical is sometimes a good choice, if so?

Edit: Went googling: Here's an example of a plano convex aspherical lens being mentioned https://www.thorlabs.com/tutorials.cfm?tabID=f7ed0dd5-3f31-4f84-9843-e0f7ac33f413

More: https://integratedoptics.com/laser-beam-collimation
 
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steve001

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I get that ,one question guys does the wavelength of light affects the collimation ? Cause i found a site saying Lens for 532 nm what if use higher or lower wavelength light?
You have a lot of questions and the best site to answer them is Sam's Laser FAQ.

Outside of that site google "laser beam collimation"
 

steve001

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Which light source should i'll be using?
To learn about laser beam collimation you have to use a laser diode. A green dpss 532 nm would be the better choice because a round beam profile is produced. Other diodes produce rectangular, oval and require additional optics generally.

Steve, your mention of biconvex aspherical caught my attention, a ~6 mm G2 lens is a slightly biconvex aspherical, I am sure for a good reason. However, for larger diameter lenses I keep finding plano convex aspherical lenses being shown as an ideal, do you know why biconvex aspherical is sometimes a good choice, if so?

Edit: Went googling: Here's an example of a plano convex aspherical lens being mentioned https://www.thorlabs.com/tutorials.cfm?tabID=f7ed0dd5-3f31-4f84-9843-e0f7ac33f413

More: https://integratedoptics.com/laser-beam-collimation
I think Edmund Optics gives an explanation.
 

Alaskan

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They do a good job, agreed. Here's a link to a good page: https://www.edmundoptics.com/resources/application-notes/optics/all-about-aspheric-lenses/

Which is best depends on what you want to do and how much you want to spend, as everything in life. i like low divergence, DPSS lasers usually have low enough divergence for what I want, but with direct to wavelength laser diodes, unless single mode, I usually want a larger diameter collimation lens with a longer focal length than the common "G2" ~6 mm diameter lenses used on many of our laser pointers. Single element aspheric lenses such as the G2 have lower loss than multi-element lenses, but the divergence is a bit higher and in the end, if you want to put more power within a small diameter at distance, or have a tighter beam as the light travels away, the higher loss 3 element lenses are my choice when using a small diameter lens. Having made that statement, some of the newer high power laser diodes being made now don't work well with a 3 element lens due to their slightly longer focal lengths, some of the beam can be cut off, or blocked within the lens holder barrel. I'm wondering if some of the light isn't truncated when using the NUBM44 diode with a G2 lens, if not, it's probably fairly close!
 
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steve001

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Steve, your mention of biconvex aspherical caught my attention, a ~6 mm G2 lens is a slightly biconvex aspherical, I am sure for a good reason. However, for larger diameter lenses I keep finding plano convex aspherical lenses being shown as an ideal, do you know why biconvex aspherical is sometimes a good choice, if so?

Edit: Went googling: Here's an example of a plano convex aspherical lens being mentioned https://www.thorlabs.com/tutorials.cfm?tabID=f7ed0dd5-3f31-4f84-9843-e0f7ac33f413

More: https://integratedoptics.com/laser-beam-collimation
Don't know.
Where do you see bi-cvx aspherics being used? There can't be a pcx asphere. It's either a pcx lens or a bi-cx asphere lens.
 
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