HL6385DG 150mw 642nm laser diodes GB - new thread

[RedlumX]

[QUOTE=mixedgas;107169]

Could you run wavelength vs temperature for that diode at cw?

I belive the factory sheet is for pulsed.

Well I can't measure wavelength accurately in absolute terms, only relative. For absoulute measurements I got a simple Monolight/Rofin Sinar spectrometer and this is hardly more accurate than 1-2nm. Next time when I set it up, I will run the Opnext diode too, and see.

But at any rate, the wavelength dependence should be in the order of 0.3nm per degree centigrade (in average; there will also be jumps in discrete steps). So for 25->15 degrees, say, the shift should be in the order of 3nm, just noticeable by the eye. I found it difficult to go to go colder due to moisture condensation, this would require an air tight enclosed setup.

[tocket]

What if you measure the wavelength relative to a known wavelength? In this case a He-Ne laser seems very suitable.

Anyway, I think we'd be quite happy with 1-2 nm resolution, but many are probably interested in what happens at higher temperatures as not everyone uses TEC.

[RedlumX]

Sure, the HeNe is used to calibrate the RSO6105 spectrometer, but the resolution of that is not too great, being in the order of 1-2nm. As for the CCD spectrometer, I guess I could calibrate it but this would require some work incl computations and right now that's not a priority - absolute wavelength measurements are not that often important.

Well the first question was a wavelength vs temperature plot of the diode - if you don't want to cool it, then that's not necessary anyway... as there is much less reason to heat it ;-)

[drlava]

So far I'm liking this diode a lot. The beam is extremely bright and easy to collimate So far I've hit 130mW measured output at about 290mA. Be on the lookout for a few modules at SELEM!

[buffo]

Which lens are you using, Andrew?

Adam

[RedlumX]

Actually I used Lens-27 from Roithner which is quite expensive but gives 15% or so more power than other collimators. However, the beam pattern doesnt look nice, in particular there is a disturbing narrow stripe of light which extends pretty far below and above the main beam. It eats only 1-2% of the power but may be disturbing, in this case one would need an iris in order to suppress it. Is this pattern normal?

[p1t8ull]

Actually I used Lens-27 from Roithner which is quite expensive but gives 15% or so more power than other collimators. However, the beam pattern doesnt look nice, in particular there is a disturbing narrow stripe of light which extends pretty far below and above the main beam. It eats only 1-2% of the power but may be disturbing, in this case one would need an iris in order to suppress it. Is this pattern normal?

I don't think it's a fault of the LENS27, a lot of the higher power DVD diodes (and IIRC these have it too) have slight ghost curtains visible either side of the unfocussed oval spot on the slow axis and these focus into the faint line.

[RedlumX]

I should have added that the ghost pattern does not show for the Aixiz coated glass lens and for the Roithner GS 8019A. But I think the latter two lenses do not sample as much light from the diode and so cut off these reflections; I believe the reason why the Lens-27 yields more power is because it collects light from the diode from larger angles, thereby including some side lobes. Indeed the pattern rotates with the diode, and not when rotating the collimator.

Strangely, for the two cases I tested, the pattern has not the same strength, ie for one diode/collim combination it is much stronger than for the other combination (each case is a Lens-27 with a HL6385DG).

[tocket]

I have seen this with DVD diodes as well. While it may not be desirable in the final module, it is at least somewhat useful when building it, as it gives the polarization of the beam. It makes the rotational alignment for the PBS cube really easy without having to use a power meter.

[drlava]

In that test I used the CAY046 lens, and see the die stripe as well. It's not an issue in a projector, the stripes are clipped by the galvo mirrors. The LENS27 will probably yield a bit more light as it is AR coated.