Good green laser diode?

[Voldy356]

I'm looking for a 1W green laser diode with an actually circular beam and good divergence?
If there even is such a thing.
Sorry in advance for the stupid question.

 

[paul1598419]

There really isn't. At best, the NDG7475 has a rectangular beam profile as do all of the 1 watt diodes or the ones close to 1 watt. You will never get a Gaussian beam out of any direct diode laser.

 

[Encap]

What Paul said above^^^

There are no diodes of any wavelength the output a round/Gaussian beam w. excellent low divergence.

IF you want a better beam quality green laser you should go with a 532nm DPSS green .
Jetlasers makes some excellent quality 532nm DPSS laser see: https://www.jetlasers.org/index.php...pander-no/49-goggles-no/29-power_levels-400mw

You can read more about green laser and other wavelength pointers here: https://en.wikipedia.org/wiki/Laser_pointer
See description of DPSS and Diode types here: https://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser
Will help to give you some minimal knowledge of lasers and not have to ask so many basic questions here.
Also use the LPF Search function.

 

[steve001]

I'm looking for a 1W green laser diode with an actually circular beam and good divergence?
If there even is such a thing.
Sorry in advance for the stupid question.

What others said is true, but they did not mention that the beam can be circularize by using beam shaping optics. If you can put up with a square beam profile then an optic that slows the fast axis is what needed and easier than two optics.

 

[RedCowboy]

What others said is true, but they did not mention that the beam can be circularize by using beam shaping optics. If you can put up with a square beam profile then an optic that slows the fast axis is what needed and easier than two optics.

Do you own a laser with it's beam circularized like that ? With a single lens used to slow the fast axis that is, if so I would like to know how well a single lens improved the divergence and did you employ this lens before or after your collimating lens ?

I understand how this works of course, just like to see an example and know how it compares, also if using say a nugm03/ndg7475 and employing said single lens before your collimating lens I assume you couldn't use a standard M9 barreled collimating lens, also where did you buy the lens, how much was it and do they have any more ?

 

[steve001]

Do you own a laser with it's beam circularized like that ? With a single lens used to slow the fast axis that is, if so I would like to know how well a single lens improved the divergence and did you employ this lens before or after your collimating lens ?

I understand how this works of course, just like to see an example and know how it compares, also if using say a nugm03/ndg7475 and employing said single lens before your collimating lens I assume you couldn't use a standard M9 barreled collimating lens, also where did you buy the lens, how much was it and do they have any more ?

I've no practical experience because finding experimental grade cylindrical lenses for experimentation appear not to exist. But like you I know there are articles on Fast Axis Collimation (FAC) of laser beams. What I don't know is if the FAC lens is placed before or after the collimating lens (if a collimating lens is needed at all). Intuition suggests the FAC lens is place first close to the diode do to the high native divergence raw diodes have.
All parts, lens mounts, would probably and should be custom machined.

 

[RedCowboy]

I've no practical experience because finding experimental grade cylindrical lenses for experimentation appear not to exist. But like you I know there are articles on Fast Axis Collimation (FAC) of laser beams. What I don't know is if the FAC lens is placed before or after the collimating lens (if a collimating lens is needed at all). Intuition suggests the FAC lens is place first close to the diode do to the high native divergence raw diodes have.
All parts, lens mounts, would probably and should be custom machined.

A single lens that slows the fast axis won't do anything for the slow axis which is still much too divergent coming straight out of a 7475/03 diode, I would expect a G2 or other short FL collimating lens would be used ( focused to infinity ) then the single optic to slow the fast axis which would in effect freeze the uneven divergence of the fast/slow axis yielding a rectangle shaped beam that would look better in the far field than with just the G2 as the beam will become ever wider proportionally as it propagates with just a G2 or 2 element, however with a c-lens pair or a single fast axis shaping lens used after the G2 the beam will propagate more evenly as the fast axis has been slowed to match the slow axis.

You could use a single fast axis slowing lens before your collimating lens in order to match as close as possible the fast axis to the slow axis, but because of how fast the slow axis diverges straight out of the facet the beam would be wider by the time ( distance from the facet ) needed to mechanically mount the lens, so a collimating lens wider than our typical M9 barreled G2/2E lens would be needed........The point of using a G2 ( just like when employing a c-lens pair ) is to grab the beam near the facet before it has diverged so much, otherwise your beam will be quite wide......yes you could use more glass after that but it defeats the point.

However using a G2 then the fast axis slowing lens would produce a more square beam than the c-lens pair and produce a narrower beam.........but come far field the c-lens pair will prove to have held a lower divergence if both c-lens pair and single fast axis slowing lens were optimized.

As for availability I expect Thorlabs and Newport will have them but the price will likely be quite high compared to available c-lens pairs.

 

[steve001]

A single lens that slows the fast axis won't do anything for the slow axis which is still much too divergent coming straight out of a 7475/03 diode, I would expect a G2 or other short FL collimating lens would be used ( focused to infinity ) then the single optic to slow the fast axis which would in effect freeze the uneven divergence of the fast/slow axis yielding a rectangle shaped beam that would look better in the far field than with just the G2 as the beam will become ever wider proportionally as it propagates with just a G2 or 2 element, however with a c-lens pair or a single fast axis shaping lens used after the G2 the beam will propagate more evenly as the fast axis has been slowed to match the slow axis.

You could use a single fast axis slowing lens before your collimating lens in order to match as close as possible the fast axis to the slow axis, but because of how fast the slow axis diverges straight out of the facet the beam would be wider by the time ( distance from the facet ) needed to mechanically mount the lens, so a collimating lens wider than our typical M9 barreled G2/2E lens would be needed........The point of using a G2 ( just like when employing a c-lens pair ) is to grab the beam near the facet before it has diverged so much, otherwise your beam will be quite wide......yes you could use more glass after that but it defeats the point.

However using a G2 then the fast axis slowing lens would produce a more square beam than the c-lens pair and produce a narrower beam.........but come far field the c-lens pair will prove to have held a lower divergence if both c-lens pair and single fast axis slowing lens were optimized.

As for availability I expect Thorlabs and Newport will have them but the price will likely be quite high compared to available c-lens pairs.

I've searched for video tutorials on using beam shaping optics and to date I've found none. Experimentation is certainly needed.

 

[barthchris]

I'm actually quite impressed with the NUB 03 after removing the gball lens and using a two or three-element lens. The far-field profile is still a line but MUCH less than the gball or a g2 lens. Other than some kind of corrective optics that will take patience and skill to install and make portable your best bet would be an expensive DPSS.

 

[WizardG]

FAC lenses, in my limited experience, are usually glued directly to the laser diode die itself, right on the emitting surface.