My 473nm DPSS.

[CurtisOliver]

Hi everyone,
I just wanted to share with people my new 473nm DPSS lab.
It is quite surprising the difference between 465nm and 473nm unless you have one of those higher wavelength diodes. I am a useless photographer but I have shared some images of the laser, with an attempt to photograph the beam. The room wasn't dark enough for the camera. The laser operates at roughly 200mW at the moment, but before I brought it, it had been known to hit 300mW. I will LPM this laser when I get a adapter. It comes with a picodrive, with potentiometers to control TEC and Diode temperature etc. I need to play around with these in order to get the power back up. I believe that if I turn up the current of the TEC, it will cool the laser down more. As at the moment, it starts up more powerful and then loses power. The longer the laser runs, the hotter it gets, so this should counteract this. Due to somebody else's post, it has been said that 473's like it cool, in contrast to that of a 532. Any suggestions?

Thank you Styropyro :beer:

 

[diachi]

Re: My 475nm DPSS.

I will LPM this laser when I get a adapter. It comes with a picodrive, with potentiometers to control TEC and Diode temperature etc. I need to play around with these in order to get the power back up. I believe that if I turn up the current of the TEC, it will cool the laser down more.

Very nice - it'll look awesome next to some 488!

Are you sure the TEC pots control current and not set temperature? Keep in mind that TECs can both heat and cool. While some drivers may be set up to only control current and maintain one polarity (thus only ever cooling or heating, not both), some TEC drivers can switch polarities in order to do both.

I'd imagine that you'll have two TECs in there - one for the diode and one for the crystal set. Both temperatures are important for efficiency. Keep in mind that it takes some time for the temperature to actually reach the set point, you should wait several minutes between adjustments before making another.

Can't remember of LBO/BBO (The non-linear crystals commonly used in 473nm DPSS) like it hot or cold ...

 

[CurtisOliver]

Yes, you are right, one is crystal and one is diode. I was going to cool the crystal a little more. I believe that increasing the current on the TEC, it should work harder to cool the laser down. I am about to update, with 5 new images. I have literally only just taken them. As for it being next to my 488, I would more than happily pair them in a beam shot once I learn how to take better photographs with a iPhone. 473 has become on of my favourite wavelengths alongside 589.

 

[diachi]

Yes, you are right, one is crystal and one is diode. I was going to cool the crystal a little more. I believe that increasing the current on the TEC, it should work harder to cool the laser down. I am about to update, with 5 new images. I have literally only just taken them. As for it being next to my 488, I would more than happily pair them in a beam shot once I learn how to take better photographs with a iPhone. 473 has become on of my favourite wavelengths alongside 589.

Probably the same design as the other CNI heads in that sort of power range - the B&W Tek 473s also use a mostly similar design.

Remember to only change one at a time - and note where the pot was previously. Assuming it is just pure current control then yes, you are correct, upping the current will lower the temperature on the cool side of the TEC - more current means the heat gets moved from one side to the other "faster".

Don't be surprised if your phone captures 473 and 488 as the same colour - they'll look way different to your eyes, but cameras often have a hard time seeing the difference.

You should get a dichro for combining the 473 and 589s (dichro for red/blue or green/blue may work well enough...) - you should get a nice white if the proportions are correct - or an off-white if not. Both being DPSS will lead to a nice match too. Could always use a PBS cube if you can't find a dichro.

Looking forward to seeing more pictures!

 

[CurtisOliver]

Remember to only change one at a time - and note where the pot was previously. Assuming it is just pure current control then yes, you are correct, upping the current will lower the temperature on the cool side of the TEC - more current means the heat gets moved from one side to the other "faster".

Will do, I am a bit hesitant to modify the laser at the moment anyway.

Don't be surprised if your phone captures 473 and 488 as the same colour - they'll look way different to your eyes, but cameras often have a hard time seeing the difference.

I know, I found this out a little today. Some of the spot looks 490nm, and the other 450nm. No in between. Shame as that is exactly what I needed.

You should get a dichro for combining the 473 and 589s (dichro for red/blue or green/blue may work well enough...) - you should get a nice white if the proportions are correct - or an off-white if not. Both being DPSS will lead to a nice match too. Could always use a PBS cube if you can't find a dichro.

Looking forward to seeing more pictures!

Yes, I might try this. I will have to get a 50% filter for the 473 as it is over double the power of my 589. 200mW of clean DPSS white. Sounds nice!

 

[diachi]

Will do, I am a bit hesitant to modify the laser at the moment anyway.

Fair enough - enjoy it some before you mess around!

I know, I found this out a little today. Some of the spot looks 490nm, and the other 450nm. No in between. Shame as that is exactly what I needed.

It's very rare to see a picture that captures them both accurately - especially 488, most cameras really can't do it justice. At least cameras that are affordable for any regular person...

Yes, I might try this. I will have to get a 50% filter for the 473 as it is over double the power of my 589. 200mW of clean DPSS white. Sounds nice!

Is this the driver you have? If so - don't worry about the filter - that driver has analogue modulation - you can control the output with that. May not be linear because it's DPSS, but it'll be "good enough".

5 Characters ... I wish the count would include quotes.

 

[CurtisOliver]

Yes, I really do not want to mess this laser up. I enjoy it too much. Probably need a good DSLR.
Not going to affording one of them anytime soon. I didn't know I could do that with that driver. How do i run an analogue signal through? I haven't ever modulated my lasers.

 

[diachi]

Yes, I really do not want to mess this laser up. I enjoy it too much. Probably need a good DSLR.
Not going to affording one of them anytime soon. I didn't know I could do that with that driver. How do i run an analogue signal through? I haven't ever modulated my lasers.

I hear you on the DSLR - would love to get into some hobbyist level photography - especially astrophotography but that stuffs expensive...

Really all you need is a 0-5V adjustable voltage source of some kind. An LM7805 or other 5V regulated supply and a 10k pot works just fine. Some drivers have a 5V out that you can use too. MOD- goes to GND on your 5V supply, MOD+ goes to the wiper on the pot, 5V+ goes to one leg of the pot and the other goes to GND too - basic voltage divider.

 

[CurtisOliver]

Astrophotography would be excellent. But nothing like capturing the beauty of a laser beam Thank you for the help in analogue modulating.

 

[BowtieGuy]

Hi Curtis, that's a sweet little 473nm labby you got there, can't wait to see your other pics!
BTW, I agree with you and diachi, I'd love get involved in some higher quality laser photography.

 

[CurtisOliver]

Thank you BowtieGuy. I had three images earlier, but I posted 5 more. I am going to try and get some shots in a dark studio when I get a chance. Might bring my 589 and 532 along as well. I think it is important for our purposes to have good images as it shows of our lasers off better. Unless you own the wavelength yourself there isn't anyway of accurately demonstrating the true colours and beauty of what you see in real life.

 

[ultimatekaiser]

Each one has an optimal range. they're often able to achieve powers higher than offered by the factory, but the head is unable to displace the heat fast enough. Usually one tec for the diode and one for the crystals. The higher you turn it up the faster you will burn up the diode and possibly the mirror coatings if it becomes too extreme. It may be able to reach various powers briefly, but not permanently. I'd be willing to calibrate and work on it for you, but probably expensive to do since i live in the USA. Typically, 200mW-350mW ish at near TEM00 is the range those should be capable of when new, but only when everything is perfectly in balance. Its probably getting hot because you've set the TECs really high and so it's trying to cool the internals to very low temps, which puts stress on entire system and creates moisture in the head which will destroy it quickly. Through that line, if present and isn't glare in the pics, looks like a collision inside the head. put on gloves and carefully check your alignment. some of these have an aluminum shield that blocks back reflections and if they mounts migrate, then they clip the edge of the pinhole and have to be panned back into place. its best not to mess with the setup of these lasers. can you send pics of the cavity and the driver? I might be able to advise you on what to move and what not to. or if you catch me on skype I can walk you through some alignment. I'm on frequently if im not at work.

 

[CurtisOliver]

Each one has an optimal range. they're often able to achieve powers higher than offered by the factory, but the head is unable to displace the heat fast enough. Usually one tec for the diode and one for the crystals. The higher you turn it up the faster you will burn up the diode and possibly the mirror coatings if it becomes too extreme. It may be able to reach various powers briefly, but not permanently. I have not touched the potentiometers yet so it is how I recieved the laser. I'd be willing to calibrate and work on it for you, but probably expensive to do since i live in the USA. Thank you for the offer Typically, 200mW-350mW ish at near TEM00 is the range those should be capable of when new, but only when everything is perfectly in balance. Its probably getting hot because you've set the TECs really high and so it's trying to cool the internals to very low temps, which puts stress on entire system and creates moisture in the head which will destroy it quickly. The laser doesn't even feel warm after usage, so I believe the TEC's are doing a good job already. Through that line, if present and isn't glare in the pics, looks like a collision inside the head. put on gloves and carefully check your alignment. some of these have an aluminum shield that blocks back reflections and if they mounts migrate, then they clip the edge of the pinhole and have to be panned back into place. its best not to mess with the setup of these lasers. can you send pics of the cavity and the driver? I might be able to advise you on what to move and what not to. or if you catch me on skype I can walk you through some alignment. I'm on frequently if im not at work.

Thank you, I'll try and send you some pictures next week. The line is present, and I believe this might be responsible for some power loss. The line is on one side so it is likely that some of the beam is hitting the shield.

 

[ultimatekaiser]

Yeah I wouldn't mess with the settings...does look and sound like something has shifted inside. I just wanted to cover all my bases in one post although frankly it is kind of odd for those to move they usually glue them down.

 

[CurtisOliver]

I will have to check this out, and get back to you on your offer. The output and beam profile is still very good, just it has a line to one side. At least that should be rule out an issue with the crystals. Thank you for your help UK.