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 1.5×1" in size) I think I’ve finally nailed the process to use for transmission masters.
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.
If you’re a holographer and you’re like me, you use your developer for as long as you can before throwing it out.
Some people will preserve their developer by floating another tray on top of it but that’s never appealed to me because it’s messy and I would need a place for the "lid" to sit and drip while I’m actively using the developer.
For some time I’ve been using various forms of tupperware which has worked pretty well and I just recently decided to give a combination of Biokips and Wine Savers a shot.
For several weeks I had a functionally dead Spectra Physics 907 laser. This was especially bad because this laser is the one I use for mastering my holograms which meant I couldn’t make anything new until it was fixed.
During those weeks I picked brains and websites far and wide and managed to get the laser lasing again (several times in fact) but couldn’t get the beam quality back the way it was before I screwed it up. I ended up enlisting the help of a local laser expert and was able to get beam power and quality back where it needed to be.
What follows is a tutorial on how to re-align an external mirror laser. Most specifically the Spectra Physics 907. I also include some tips on cleaning the mirrors and removing stuck boots.
Before I go any further I want to thank the following people:
The guys at the Holography Forum who provided suggestions for getting the beast aligned. Tony, BobH, Wler, Colin, Ron Michael, Martin, JohnFP, dcgman.
Sam Goldwasser for making public such a treasure-trove of information about lasers.
Tom Ehrichs for spending time cleaning and aligning the laser. I gained as much by watching him work as I did by him working.
If you’re using machine shop magnetic bases on your holography table you’ve no doubt discovered that they wobble a bit.
This is a definite no-no when it comes to holography as that creates a weak point where vibration can continue to exist in your table.
The best way I’ve found to level the bases isn’t to sand them level but rather to use epoxy to let gravity quickly level them for you.
If you’re putting together a holography table on a budget, chances are good you’ll be using inner tubes as the primary isolation medium.
Chances are also good that you’ll need to adjust the pressure in the tubes once everything is piled on top of them.
Here’s one method for extending the valves so you can adjust the pressure anytime you need to.
Getting a good photograph of a hologram isn’t always an easy proposition but if you use the right tools and are patient you can get excellent results just about every time.
This tutorial assumes you have full control of the hologram and can take it off the wall at will. If you’re trying to take a picture of a hologram that’s permanently mounted to a wall or one where the owner won’t allow you to move it, you’ll need to adjust accordingly.
This could also have been called optic destroying with collodion. You’ll see why in a bit.
Based on my first three attempts, I wouldn’t recommend bothering to use collodion with cheap mirrors.
Collodion is used for a number of applications, such as cleaning optics used in astronomy. It was recently mentioned on the Holography forum as a way to clean our precious mirrors and lenses.
Here’s the first mirror with a tape dam at an angle which attempts to show all the crud on the mirror. It’s not excessively dirty like you might get with optics used in astronomy but it’s dirty enough that it’s interfering with my reference beam light. The mirror is used to steer the light coming out of my spatial filter up to my collimating mirror and needs to be as clean as possible. Note that this was a cheap $1 mirror I bought at a local electronics shop.
Cutting glass isn’t hard and if you’re budget minded won’t cost much. Some of
the benefits of learning to cut your own glass are:
Note that the instructions which follow assume a right-handed user. If you’re
a lefty you’ll need to adjust accordingly.
Making a safelight for use with red sensitive film (actually any monochromatic film) is easy and by using the right materials you can make a light that is both bright and won’t fog your film.
You might be tempted to use LimeLites and while that will get you by for quite some time, just as nothing beats a spatial filter for cleaning up a reference beam, nothing beats a bright and truly safe light.
You don’t have to break the bank though.