It's been a long time since I posted, but I have a question that you can probably answer easily.
I've been trying to get into holography and I've been struggling with a few things.
I started out obtaining a 200 mW 650 nm diode laser module, a fairly beefy aluminum heat sink, some holographic film, and a little bit of hardware to keep things from moving. I was able to get a pretty grainy-looking exposure of items 1-2 mm away from the film, but any farther and there was no detail.
I then contacted Litholo (a company that used to sell kits to beginner holography enthusiasts), and they put together one of their discontinued kits for me with a 5 mW 638 nm diode, a clip-on heat sink (very small) and some laser cut acrylic fixtures to clip the laser in place and lean the film against. It didn't *seem* sturdy to me, but I was able to get somewhat better results with their setup than with mine; however, the exposure time is super long - they recommend 10-15 minutes, but I've tried 25-30 minutes before I got any promising results. Still, though, the depth of field is super shallow- maybe 2-2.5 cm, and you really only see good detail the first 3 or 4 mm. I tried their hardware with my other lasers and I can only capture fairly faint images. I even said to forget about vibration, and tried an exposure with a high powered (>500 mW) fan-cooled laser, just to see if I could make out any detail, and, shockingly, even with the vibration of the fan (the vibration is said to spoil the fine structure of the interference pattern recorded on the film that makes the hologram), I'm getting about the same results as my 200 mW 650 nm.
I've checked these lasers with a polarized filter and examined the projected spot to verify that the lasers I'm using are TEM00, and, I can't really tell. The seller told me that the laser was TEM00, but my very crude interferometer ($20 amazon beam splitter and a front-surface mirror I scavenged from the trash in a lab I used to work in) didn't produce a very clear interference pattern.
I would simply do a longer exposure with the laser Litiholo supplied to me, but a) I'm worried about cooking the laser and b) I really want to understand what's going on, physically, that is preventing me from using whatever single mode laser I want.
I've reached out to Litiholo for help, but all they told me was that they select their lasers specifically for making holograms. I don't think I'm doing anything that would negatively affect their business by trying to upgrade the kit that I already bought from them.
I truly don't believe that my problem has anything to do with mechanical stability. Either the wavelength of the laser is unstable (which I think may be, but I don't know how to prevent this or even quantify it).
I'd appreciate any advice.
I've been trying to get into holography and I've been struggling with a few things.
I started out obtaining a 200 mW 650 nm diode laser module, a fairly beefy aluminum heat sink, some holographic film, and a little bit of hardware to keep things from moving. I was able to get a pretty grainy-looking exposure of items 1-2 mm away from the film, but any farther and there was no detail.
I then contacted Litholo (a company that used to sell kits to beginner holography enthusiasts), and they put together one of their discontinued kits for me with a 5 mW 638 nm diode, a clip-on heat sink (very small) and some laser cut acrylic fixtures to clip the laser in place and lean the film against. It didn't *seem* sturdy to me, but I was able to get somewhat better results with their setup than with mine; however, the exposure time is super long - they recommend 10-15 minutes, but I've tried 25-30 minutes before I got any promising results. Still, though, the depth of field is super shallow- maybe 2-2.5 cm, and you really only see good detail the first 3 or 4 mm. I tried their hardware with my other lasers and I can only capture fairly faint images. I even said to forget about vibration, and tried an exposure with a high powered (>500 mW) fan-cooled laser, just to see if I could make out any detail, and, shockingly, even with the vibration of the fan (the vibration is said to spoil the fine structure of the interference pattern recorded on the film that makes the hologram), I'm getting about the same results as my 200 mW 650 nm.
I've checked these lasers with a polarized filter and examined the projected spot to verify that the lasers I'm using are TEM00, and, I can't really tell. The seller told me that the laser was TEM00, but my very crude interferometer ($20 amazon beam splitter and a front-surface mirror I scavenged from the trash in a lab I used to work in) didn't produce a very clear interference pattern.
I would simply do a longer exposure with the laser Litiholo supplied to me, but a) I'm worried about cooking the laser and b) I really want to understand what's going on, physically, that is preventing me from using whatever single mode laser I want.
I've reached out to Litiholo for help, but all they told me was that they select their lasers specifically for making holograms. I don't think I'm doing anything that would negatively affect their business by trying to upgrade the kit that I already bought from them.
I truly don't believe that my problem has anything to do with mechanical stability. Either the wavelength of the laser is unstable (which I think may be, but I don't know how to prevent this or even quantify it).
I'd appreciate any advice.