Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers
Buy Site Supporter Role (remove some ads) | LPF Donations
Links below open in new window
PHR-803T - Coherence Length
- Thread starter goahead
- Start date
- Joined
- Oct 1, 2008
- Messages
- 132
- Points
- 18
I'm curious about this too
In the meantime i received my LD and made some reflection holograms on DCG plates. The deepest scene was 6cm. This would indicate a coherence length of at least 12cm for the diode tested.
Between 70mA and 90mA there is a broad stable operating region.
I was quite surprised that it was possible to get any hologram at all, because the broad spectrum published for eg. the Sharp Bluray- LD (GH04P21A2GE) had made me to expect nothing good from this LD.
Between 70mA and 90mA there is a broad stable operating region.
I was quite surprised that it was possible to get any hologram at all, because the broad spectrum published for eg. the Sharp Bluray- LD (GH04P21A2GE) had made me to expect nothing good from this LD.
Years ago I made a couple of holograms on the 8E75HD plates and I've always dreamt of using DCG one day. The arrival of the cheap 405nm's has also renewed my interest. Am I correct that you can use it without a sensitizer at 405nm? Or do you still use some kind of sensitzer dye, goahead?
About the coherence length, I once read an article where they used the backreflection from a simple microscope coverglass in the collimated beam to force the laser into single longitudinal mode operation. Might be worthwile to experiment with that.
About the coherence length, I once read an article where they used the backreflection from a simple microscope coverglass in the collimated beam to force the laser into single longitudinal mode operation. Might be worthwile to experiment with that.
Sorry i did not reply earlier. It's a DCG mixture without sensitizer because it's not needed at all with 405nm.
The components for the mixture were: 2g gelatine, 1.7ml 5% Ammoniumdichromate (85mg), 16.5ml H20.
The sensitivity was around 2mJ, so the exposure times were a few seconds.
You can read here about how it went:
http://holographyforum.org/phpBB2/viewtopic.php?f=20&t=6493&sid=d88c1f012b85504f5aeefbf1a93357cf
I'm using the reflections off a glass plate to see the fringes and to find the most stable current range, but never tried using a microscope coverglass as etalon. It might be worth a try.
Thanks for the tip.
The components for the mixture were: 2g gelatine, 1.7ml 5% Ammoniumdichromate (85mg), 16.5ml H20.
The sensitivity was around 2mJ, so the exposure times were a few seconds.
You can read here about how it went:
http://holographyforum.org/phpBB2/viewtopic.php?f=20&t=6493&sid=d88c1f012b85504f5aeefbf1a93357cf
I'm using the reflections off a glass plate to see the fringes and to find the most stable current range, but never tried using a microscope coverglass as etalon. It might be worth a try.
Thanks for the tip.