Dragon's Eye News

The on-board software is finally (no, really) ready to be wired up in the lab and I expect to do that tomorrow sometime.

The prototype controller is shown below with LEDs in place of connections to the relay board. I'll likely leave those in as I'm wiring the two together so that I can clearly see that both ends are working. The lit LED below is a temporary status light that shows me the software on the Arduino is running.

The resistors are all 10K pull down resistors for input from the several switches that I've got on my workbench for turning laser and shutter power on/off. The 10K pot serves as a stand-in for the light sensor that sits above the table and is used to verify that the shutter opened as expected. Two voltage regulators provide 9v and 5v for various applications. I'll be expanding their circuits soon to add diode protection and capacitor smoothing. An external board has TIP20's for controlling the 1W LED status lights out in the hallway. At the moment they just blink or are steady-on but with the Arduino I can make them fade and add sound back back to the experience with an external piezo speaker. I miss having an R2D2 in the hallway like I did with the Lego RCX controller I started out with.

I've got one digital and one analog pin open so sometime soon I expect I'll be expanding the system with more monitoring and someday with a touch screen or something similar.

The Arduino software is capable of driving the lab all by itself but since it doesn't have a UI, I still need to use the PC to provide an easy to use input interface.

I've updated the HoloController software with an Arduino driver that simply sends port commands like the K8000 driver did and otherwise still controls the lab and exposures. Soon I'll modify the PC software so the Arduino handles all the work which means the interface will move to an all-serial command set that can be more easily ported to other languages. The protocols are all written and tested now.

Woot! for Arduino!

A view of the table is available over here.

Technorati : arduino, automation, hologram, holography, lab
Del.icio.us : arduino, automation, hologram, holography, lab

Ugh. I went to power up the table on Saturday and discovered the main controller wouldn't come on.

At first I thought the laptop had frozen (it doesn't this every once in a blue moon) but no, it was running just fine.

Poking around under the table revealed a slightly melted fuse cover on the main controller and a fuse with no wire at all.

The recent electrical storms had apparently tried to toast the controller.

After purchasing some new fuses I found that the recent electrical storms had succeeded in frying the controller. As soon as I turn it on the fuse blows in a spectacular way. Short in the transformer? That's what I'm hoping.

For what seems like forever now, I've been working on developing a DCG process for myself that I could use when making white-light copies of my silver masters.

After some inconsistent results I stripped the table top of all components and set up an interferometer to see how stable the table was.

While giving a talk about holography to a school group recently I mentioned that one could look at a hologram through a microscope and see what you'd see with the original subject.

Since I've got an Intel QX3 microscope I decided to capture a few images.

I've been working on a couple of holograms recently and while I don't have a lot of time for blogging at the moment, here are a few pictures.

The dancing shoes turned out really nice both in master and copy.

The next one was a quickie for Wifey and her mother.

It's a commemorative pitcher from Union Station in Ft. Worth.

VRP-M is working out pretty well so far, even the old film from Oct 2005 is coming out ok.

OneNote has been written about ad-infinitum as a tool for note taking in meetings and classes, as a general information repository and as a collaboration tool but I'd like to introduce you to another use that I'm putting OneNote to.

Making holograms.

Or more specifically, documenting both the process I go through when creating a hologram and the results from that process in the form of notes and pictures.

As most of you will probably know, OneNote is a great repository for all sorts of information. It has allowed me to combine a number of sources into one place so that when needed, I can easily refer back to previous results when I'm making a new hologram.

For almost two months now, I've been working to figure out the exposure and processing steps to use in order to get bright and clean transmission holograms using my Coherent 315M and VRP-M film.

After blowing through roughly 68 pieces of film (mostly 1.5x1" in size) I think I've finally nailed the process to use for transmission masters.

JohnK on the holography forum had asked if I'd experienced any problems with delayed development of VRP-M.  He's been working on making holograms using a Coherent 315 and VRP-M film and was wondering VRP-M was sensitive to delays of several hours between exposure and development.

I normally develop right after exposure but did the following test to find out how VRP-M behaves.

It's time for another labcast and this time I'm experimenting with making a copy onto PFG-01 from a test "master" made using the 315M and VRP-M film.

The final test turned out pretty decent and was exposed for 12s, developed for 30s in TJ1 and bleached with EDTA.

The final image isn't as bright as I'd want if this weren't just a quick test but overall it's not bad. I may have time tomorrow morning to try another test with fresh developer but then again all my time might be spent watching the lunar eclipse.

Here's the cast. Let me know what you think.

If you find yourself needing to take your laptop into the lab, you can make life simpler by making a safelight cover for the screen.

I know most of you who make holograms don't carry around a tablet and those who carry around one probably don't make holograms but for others who, like me, do both, here's a way to take the computer into the lab without having to turn the screen off while film is out and about and you can save your "night" vision for what is probably a dimly lit lab.

I don't know how often I'll do these but I had the urge to record what I was doing in the lab.

I've been trying to get good results with the coherent 315 laser and VRP-M film and haven't had any luck. In each case where I've gotten any kind of image, it's been extremely dim.

Unfortunately I found that my shutter was causing a full seconds worth of ringing in the table and had to build a new shutter. That was completed yesterday and this morning I'm doing some more exposure and development tests.

My apologies for the sound quality. Next time I'll have to make sure the microphone is closer to me at all times.

Without further ado, here's my labcast.

Let me know if you'd like me to do more of these.

Well, it turns out that one of the problems I was having with my green laser and the VRP-M film is my shutter.

When it opened it set the table to ringing for at least a full second.  My 2-4 second exposures were incredibly dim because they were getting fogged for the first second.  I found this out after setting up an interferometer (shown above, click for a larger picture) opening and closing the shutter while it was going.  The fringes really moved when the shutter closed but as no light would have been reaching the film, I didn't care about that.  Have it shake the table when opening was a problem though.

I tried all sorts of things to improve the isolation of the shutter and damp the vibrations it was putting out but in the end I had to give up and make a shutter from scratch.

I took a panel meter and attached a multi-layered piece of aluminum foil and used that reflect the incoming beam and create a beam dump on the inner surface of the meter housing.  Painting the whole thing black created a nice little box to keep the beam in.

After putting a couple of beads of silicone where the meter arm rests against the coil I ended up with a nice quiet shutter that didn't disturb the fringes at all.

It's being put through its first hologram-making test right now.

After several days of tests I've gotten a couple of decent transmission holograms on VRP-M using a Coherent 315m.

You ever look back at something you did months ago and wonder, "why did I do that?"

I did that this evening with the controller that I've got in my lab.

I'm starting work on another hologram for a professor at A&M and needed to do a bit of maintenance on the table. Strange, but every time a new hologram request from her comes in, there's something that needs doing in the lab before I can get started.

This time the HEPA fan wasn't shutting off during an exposure and the table light sensor wasn't working.

It turned out with the HEPA fan that somehow I'd wired up the relay connection with an additional 5v going to it. I have no idea why I did that. Fortunately it just caused the controller chip on that port to heat up (and not work) but didn't blow anything. Odd that it was working for a while and then just stopped.

The light sensor just turned out to be a loose connection at the junction between the table wiring and the controller wiring. Gremlins.

I also found a problem with the holocontroller software not always shutting off the fan and fixed that.

Now I just need to straighten up the lab, prep some film, paint the subject and shoot. All tomorrow morning.

I spent some time on Thursday night finishing up the platform for the new laser.

I've got a Kee-Klamp scaffold over my table that holds the big red laser and nothing else. I had planned to hang optics off the scaffold but that didn't quite work out. Fortunately it made a great place to put the SP-907 laser box.

Now it's got another rider in the green laser, telescope and shutter.