Seriously thinking of going pulse

[MichaelH]

I'm tired of dealing with movement causing problems in my 25mW CW table.

At the moment I'm working on putting the stake in a long-term problem I've had with my table creeping. It's not air currents and I'm 99% sure it's not components settling but instead appears to be small temperature shifts causing the inner tubes to expand and contract. At least that's my theory which is supported by the fact that if I very very gently press on one corner of the table I see the same kind of movement as I describe with the word "creep.".

At any rate, I'm tired of battling that sort of thing and am most interested in being able to make the images I have in my head (or making copies of existing images) without the hassle of movement biting me on the behind.

So, I can either greatly increase my power levels (tempting, but it looks like I'd have to go green to get 100mW+) or I can get really serious and go pulse. People are always asking me if I can do people or animals and with CW the only way is if they're dead. so...

I'm interested in feedback from you guys. I know I'd be trading the hassle of dealing with movement for the potential to blind or burn myself so that's a whole different ball game there. There's also the cost (one laser I'm interested in is $40K) but if I can find a way to make it pay, I'll go there.

What think you? For someone who really wants to get serious about this endeavor is pulse worth it, or am I just another person who's going to lose his shirt (and maybe an eye) chasing the holographic dream?

[eric343]

You may want to try one of the 100mW or 200mW MaXYZ red modules that one of the PhotonLexicon members puts together:
http://www.photonlexicon.com/forums/viewforum.php?f=10

I don't know just how decent the beam quality is, but the price is a lot better.

Though, what's wrong with the 315M? There's a reason it's the de-facto standard.

Of course, if you get a pulsed laser, all sorts of holographers will come a-kockin'. Betsy Connors (who's teaching MAS.858) was telling us how a pulsed laser was once opened to curious holonuts on the East Coast and everyone came out of the woodwork to make holograms of balls in flight and everything else.

Don't plan to make the $40k back. If you can afford to drop $40k on your hobby, do it, but display holography seems like a dead market now and for the next few years.

[BobH]

is pulse worth it

To address "creep" in your table? No!

To make copies of existing images? No!

To make imagery you see in your head? Yes, if you have the money!

Keeping a pulsed laser clean, stable and safe in a home environment will be difficult (in my opinion). Manipulation of pulsed laser light do do truely creative holography (beyond simplistic portraits floating in black space) will be a challenge. Don't go there to get away from stability issues, go there to realize your vision. And don't forget to buy a great set of laser goggles!

[Tom B.]

It's not air currents and I'm 99% sure it's not components settling but instead appears to be small temperature shifts causing the inner tubes to expand and contract.

I wonder if changes in barometric pressure could be involved? Might be helpful to set up a very high resolution barometer (an interesting problem in itself) and see if observations of rising & falling air pressure correlate with the creep. Of course small changes of temperature could be warping the table in other complicated ways as they propagate from the skin to the core of the table...

[MichaelH]

You may want to try one of the 100mW or 200mW MaXYZ red modules that one of the PhotonLexicon members puts together:
http://www.photonlexicon.com/forums/viewforum.php?f=10

Thanks for the link. Seems to be a good source of info for high power.

Though, what's wrong with the 315M? There's a reason it's the de-facto standard.

Nothing's "wrong" with it, it's in the list for consideration if I don't go pulse. Unfortunately I just bought a bunch of red film so I've got some natural resistance going. Nothing I can't overcome.

Don't plan to make the $40k back. If you can afford to drop $40k on your hobby, do it, but display holography seems like a dead market now and for the next few years.

I still wonder. I've been working to determine if that business can be viable again (not just images of "things" but portraits and "art"). I haven't convinced myself either way yet but one thing I do know is that my equipment must be ultra-reliable as far as being able to leave the lab with with a good hologram 99% of the time. Right now it's not, too much tweaking is involved to keep it 60% reliable. For me that may mean lots of power and short exposures.

To address "creep" in your table? No!

Not to address it, but that issue is just the latest that's killing my ability to leave the lab with a good hologram. The idea of going pulse is being raised mostly by my desire to do living subjects. Not having to worry about movement is a big plus for static subjects as well though.

To make copies of existing images? No!

Not just that either, but it's one data point.

Keeping a pulsed laser clean, stable and safe in a home environment will be difficult (in my opinion)

Why do you think it would be more difficult to keep clean or stable than in an office or warehouse environment, where I know some practitioners are using them? My working area is now dedicated to holography and I run a hepa fan most of the time. I can easily change that to all the time.
Safe I see if you're just referring to the dangers of working with really high power.

I wonder if changes in barometric pressure could be involved? Might be helpful to set up a very high resolution barometer

Hmmm, wonder where I could borrow one locally.

[Tony]

I kind of refuse to believe that getting a good table setup is an 'unsolvable' problem. ('Unsolvable' being defined by the amount of time and $ you're willing to put into it).

Here are my thoughts-

-If your table is being affected by the inner tubes, then it's not nearly stiff enough. Can you test this by eliminating the inner tubes and then testing again? It won't be any good for making holograms, but you might learn if it is or is not a thermal issue.

-Would it be possible to improve the stiffness of your table by adding a structural element underneath it, on top of the inner tubes? Like some steel rails/beams?

-The table stiffness is related to the size of the table (maybe even raised to a power - forgot all my ME classes). So maybe you should consider a smaller table. For example, I do everything in 4x5" format on a 2'x2' table. My laser and spatial filter are off the table. I use a 35mW Hene and have exposures up to 1 minute or more with no problems. My table is a hexcan table with 16 gauge steel skins.

I can't objectively comment on the challenges of pulsed work, never having done any myself. But they are known and described in the various texts. It seems you might be trading one challenge for another (or many others). Unless you find some specific advantage to pulse work (such as the portrait thing), I don't expect it would be worth the transition.

Finally, as for the market for display holography, I'm often wondering if there might not be a market for custom-order 'boutique' work. Like a 21st century version of bronzing baby shoes...

[MichaelH]

I kind of refuse to believe that getting a good table setup is an 'unsolvable' problem. ('Unsolvable' being defined by the amount of time and $ you're willing to put into it).

That last detail is the kicker. I'm getting weary of dorking with my tools all the time. I like playing with holography but more and more I just want my imagery to come out right.

Add that to the fact that I want to branch out as well and that leaves me wondering if it's time to take a real plunge. I've been looking at the financial side of several options but haven't seen a clear path yet.

-If your table is being affected by the inner tubes, then it's not nearly stiff enough. Can you test this by eliminating the inner tubes and then testing again? It won't be any good for making holograms, but you might learn if it is or is not a thermal issue.

I'll try that but don't expect good results. Since I'm on the second floor of a house, every little tiny movement in the house shows up on the table if it isn't damped. Can't hurt to run the experiment though.

Would it be possible to improve the stiffness of your table by adding a structural element underneath it, on top of the inner tubes? Like some steel rails/beams?

Maybe. I could also bond the two halves of my hexcel sheets together and see what happens. That should considerably increase the stiffness.

Finally, as for the market for display holography, I'm often wondering if there might not be a market for custom-order 'boutique' work. Like a 21st century version of bronzing baby shoes...

I think there is just based on the regular orders I get. It's not enough yet to cover expenses but that's one reason I'm looking at taking things to a higher level.

[JohnFP]

Nothing's "wrong" with it, it's in the list for consideration if I don't go pulse. Unfortunately I just bought a bunch of red film so I've got some natural resistance going. Nothing I can't overcome.

Michael, step back and take a deep breath and try to look at your question objectively. You are willing to drop $40K to achive your goal but don't want to give up a box or two of plates? Sell the darn things and go green with increased power.

I've been working to determine if that business can be viable again (not just images of "things" but portraits and "art").

FInd the niche first then invest high dollars if it helps the niche. I once worked for a very brilliant business man that always wanted research into new areas to overlap the business making money. That is, do the quantity and in that you may find the technique or niche that works for you and your targeted market.


Concering pulsed. One, you will find you are very limited and if you do go puled make sure you find one that can be pulsed at a relatively high rate or you will be stuck with an optics alligning nightmare. Invision it, you have a 1PPS laser and you are trying to do a split beam tranmission so that you can get decent lighting on the object. At one PPS you will find this is quite tedious. Now if you stay with that set up and do multiple objects from the same set up, your ok. But every time you want to change a set up you will spend hours and hour getting the lighting right.

My experiences with pulsed laser is that they are hard to maintain a day to day repeatability. That is, you set up the perfect set up as mentioned above, come in the next day and the mode of the laser changes slightly, you tweak the laser for tem00 and wham, the beam moved and all the optics need to be realligned. You will be battling all kinds of variables if trying to do a split beam set up.

Solve the table problem. Is there enough mass on the tubes? We used a tube and concrete table to shoot 45 minute exposures in resist. I have to agree with Tony, if you think it is expansion and contraction of the tubes then your table is not rigid enough to move as a whole. Expansion and contraction of the actual table top is more likely then the problem being with tube expansion and contraction if temperature diff it the problem. I think what Tony means by elliminating the tubes is you should not see a drift, even if the table is static to the legs/floor. You will see vibration from being on the second florr, but not drift. If you do see drift then your floor joists are sagging (resolved by having a stiffer table) or air current are affecting your mounts or beam paths. But it should narrow down or out the tube thought.

We can work this out!

Peace!

[JohnFP]

Can you purchase a hollow steel door. The ones with corrogated wood inside? This would lay right on your table and should increase stiffness if it was clamped at four points on each of your hex halved. It would also be cheap, light and easy to bring in.

[JohnFP]

Another benefit of going green is DCG.

[MichaelH]

Nothing's "wrong" with it, it's in the list for consideration if I don't go pulse. Unfortunately I just bought a bunch of red film so I've got some natural resistance going. Nothing I can't overcome.

Michael, step back and take a deep breath and try to look at your question objectively. You are willing to drop $40K to achive your goal but don't want to give up a box or two of plates? Sell the darn things and go green with increased power.

Actually I am looking at it objectively, it doesn't come across that way only because I've mentioned only one or two variables in my overall equation.

The movement problem I'm experiencing with my current setup isn't the primary reason I'm thinking of going pulse. It's just the most annoying variable. Movement of any kind is the primary reason. With CW I'll never be able to make a hologram of any animal or person, something I'd like to do for fun and profit.

Also, I'm not "willing" to part with $40K just yet, it just happens that the features I believe I want in pulse (variable output 10-100%, variable pulse frequency, etc) costs about that. I've only got solid information from one supplier so there's loads of research to do.

My experiences with pulsed laser is that they are hard to maintain a day to day repeatability. That is, you set up the perfect set up as mentioned above, come in the next day and the mode of the laser changes slightly, you tweak the laser for tem00 and wham, the beam moved and all the optics need to be realligned. You will be battling all kinds of variables if trying to do a split beam set up.

Those are a few reasons why the costs go up for modern pulse lasers. You can "easily" obtain models that are fixed-mode and pulse in the KHz range so for alignment can be treated as CW.

Can you purchase a hollow steel door...

I may try that. I'll also re-clamp my hex halves together along more points and see if that helps.

Another benefit of going green is DCG

You can do that in red too but then you throw away a bunch of the power you gained by going to a bigger laser.

[MikeJ]

My two cents.
If you have the itch for a pulse, I say scratch it!
I was at The center for Holography last month and saw some of Ikuo Nakamura's work and Monday I met with Ron Olson at Laser Reflections and saw some of his work. Both very different artists, but both created very moving images. If you want to look at it from either the artistic side or the marketing side, the pulse opens you up to a lot of opportunity. Opportunities, that may put Holograms in the hands of those who before, did not know of or consider Holography.
Good luck.

[Sergio]

Thinking into near future, technologically a pulsed green is the state of art option, from years technology centers are developing efficient Neodimium lasers with high quality, I guess a "mini" reliable pulsed model is the fit stuff here, Thinking seriously a reliable laser would fit, but following the emulsion technology an option of pulsed laser photopolymers may become a reality soon, it may arrest all worries of development and reciprocity failures regarding silver halide materials, I guess for the medium time is OK for the laser if it is reliable and rugged.

[Tom B.]

I wonder if changes in barometric pressure could be involved? Might be helpful to set up a very high resolution barometer

Hmmm, wonder where I could borrow one locally.

Hey, just make your own!

http://www.phys.unsw.edu.au/~map/weather/barometer/
(Now THAT's homebrewing)

more seriously -
http://www.belljar.net/microbar.htm

Looks like a lot of work that would be better spent on improving table stiffness. But the idea of exploring the infrasound realm is interesting....

[MichaelH]

I'm going to start a different thread for the stability discussion but I do want to continue the pulse thread.

To recap, the reasons I'm thinking of going pulse are:

1) To gain the ability to image live subjects.

2) Not having to worry about movement again ever again (assuming enough power per pulse that a breathing or slowly moving animal can be captured).


The drawbacks and questions I can think of are:

1) The ability to put out an eye or other body part with an un-diverged or insufficiently attenuated beam becomes a danger to be aware of at all times.

2) Cleanliness becomes even closer to godliness. Dirt in the optics could ruin them. HEPA fans are a must and checking everything out at low power is important.

3) FDA regulations? Is there a certification process that must be followed before people can be put in front of a beam powerful enough to capture their soul?

4) What's the day to day maintenance like for modern pulse lasers?