A Dichro to combine 520 and 532nm?

[Light superglue]

Recently I was looking for dichros to combine 532nm DPSS and 520nm LD lasers but found nothing in ebay.

However, on chroma.com they have a dichro filter 59012m for 350usd which acc. to graphs has transparency 95% for 520-525nm and only 0.14% for 532nm.

The question here is I am not sure if Dichro FILTER is meant to be the same thing as Dichro MIRROR or not? Does "dichro" mean that not (EDIT: passing) light is always reflected (EDIT: with exactly the same divergence) or can it be dissipated in other ways?

EDIT: This is the link
https://www.chroma.com/products/parts/59012m

 

[Alaskan]

You can get dichro mirrors which pass longer wavelengths and reflect higher or shorter. So much to them, some only work well at specific angles others straight on. Diachi, where are you? Encap? There are a bunch here who know a lot about them, but thought I'd offer that much. Regarding the filter question, they can band-pass, or reject specific wavelengths too. If a narrow or wide band-pass, then that can work as a filter, reflecting what it won't pass.

 

[Light superglue]

Hi Alaskan,

The question is mostly if the words Dichro FILTER and Dichro MIRROR mean the same thing or not.
If the item is called Dichro FILTER does it mean that the reflected part of a collimated beam is rejected as a collimated beam (what could work in opposite way, too) of dissipated around like by a diffuser?
By "Dichro" I understand something that does not absorb as an "ordinary" filter would do but reflects the energy or sends it somewhere else...

Yes, this is a question to a specialist (Diachi maybe?)

 

[Alaskan]

A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. In other words they are narrow pass, wide reflect, in the instance I believe you are asking, but always reflect the unwanted wavelengths, only passing the desired range of wavelengths.

 

[Light superglue]

Thank you for help, Alaskan, but at the moment I would like to have a confirmation that the unwanted colours beam is reflected with no bigger divergence than the incoming colours laser beam.
So it is more terminological question - are the terms Dichro MIRROR and Dichro FILTER strictly interchangeable or can they mean a (small) difference in properties of the two so called items?

 

[Alaskan]

As far as divergence, that shouldn't change for either the pass or the reflected, although if at an angle, I suppose, depending upon the thickness of the glass, there could be some effect for a beam passing through it as far as beam path, but not any appreciable change to divergence.

 

[CynicalBrad]

What project do you have in mind that involves combining 520 and 532? The beam specs are very different and without a lot of correction on both beams, I don't think the result would be fantastic. If more power is desired, look into the class 4 diodes (never thought I would get to say that)

As for your question, consider a dichroic filter/mirror to be a selective mirror that passes the lower wavelengths while reflecting the higher ones.

 

[Alaskan]

Not exactly what you are doing, but I've been considering PBS cube combining two different divergence lasers myself, if combing these two, the 520nm would expand so much faster than the DPSS laser, it would need some expansion, I think. Might defeat the whole idea of why you want to combine them. Although a fat beam with a brighter center section would be more impressive than a fat beam without one. Would be worthwhile, but that is what you would get. I do believe beam correction for the 520nm would be important, otherwise that output would be a rectangle while the 532nm DPSS remain a round beam.

 

[Light superglue]

Hi guys,

Thank you for comments and help.

Please let aside the PBS and correction issues - these have been discussed in many other threads... I started this thread to only ask if Dichro combining of different moderately priced green lasers is possible and the main WLs in the market are 532 DPSS and 520 LD. I found this item which could be a part needed but maybe someone can suggest a better alternative?

https://www.chroma.com/products/parts/59012m

What concerns project... the tasks can only be set after all theoretical issues resolved and needed parts sourced, otherwise it would be just talks and speculations.

 

[Alaskan]

Let us know how it works out.

 

[Benm]

On thing to realize is that there is a difference in application here:

Dichroic filters can be used to reflect specfic wavelenghts while letting others pass, but this also depends on the angle of the incoming light.

A dichroic filter that blocks a specific wavelength usually does so for light coming in at a normal angle (i.e. straight on, 90 degrees from its plane).

A dichroic beam combiner is another thing: that is designed to reflect and block specific wavelenghts at 45 degree angles, allowing you to combine beams from two laser sources sitting at 90 degree angles from eachother.

Both share the same operating principle, but a dichroic mirror for 633 nm at a 90 degree angle (which you could use in a HeNe laser) is NOT a dichroic mirror for 633 nm when hit at a 45 degree angle (in case you wanted to combine that HeNe with some other laser).

 

[Light superglue]

Thank you Benm,

Finally an answer showing how stupid I am.
I looked at the Graph for 0° angle of incidence and that´s why it is called filter - because it is working as a filter at such AOI.

To combine beams I need to check the Graph at 45° AOI.

And this is it - among so called "dichroic beamsplitters"... but at 475usd.

Too expensive for a try.