1st time on DCG Project

Dichromated Gelatin.
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admin_jsfisher
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Re: 1st time on DCG Project

Post by admin_jsfisher »

You may find the attached PDF useful.
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Coherent - Unknown - Operator's Manual Compass 215M Diode-Pumped Laser.pdf
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pluto
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Re: 1st time on DCG Project

Post by pluto »

My emulsion look like a water should it be thicker? (100-12-3)
If your emulsion has a watery consistency at room temperature, something has gone wrong. Make sure you never heat your emulsion (at any point) above 50c, as this causes the gelatin to decompose.
When I developed first my 3 plates it came out full of crystal tree, milky in the edge whith a little rainbow and cloudy in the middle, cloudy all over the plate.
I use ilford rapid fixer 1:5 -> Water -> ipp 54% 58% 75% 80% 100% -> heat gun (all bath at 22°C) Exp 10 min with 8$ 5mw pointer laser 12hr dark reaction.
First of all, let me say that your process is too complicated for a beginner. I recommend doing the minimum amount of steps until you successfully make a hologram, then start introducing new steps slowly. You don't want to have a lot of variables right at the beginning, as it will be far too difficult to troubleshoot any problems you might have.

I recommend the following process:

After exposure, leave in the dark for up to 30 minutes. This can be extended, but I think it's more important that you are able to rapidly create holograms and improve your process. Simply fix your hologram with a 100 watt halogen light held 6 inches away for 5-15 seconds. Then do your water bath, 70% IPA, then 100% IPA. Blow dry with a heat gun.

Now most importantly -- the laser pointer you're using is almost certainly not suitable for holography. Some cheap red laser pointers can be used with silver halide emulsions, but they are NOT suitable for normal DCG holography. The DCG formulation you're using is extremely insensitive to red light. Keep in mind, it's so insensitive that we can use a bright yellow safelight. There are special DCG formulations which use dyes to increase its sensitivity to red light, but it involves hard to obtain chemicals and is probably a bit too complicated for a beginner.

I suggest you do some reading about the principles of holography and lasers. There's a reason we shell out big bucks for holography lasers :)

Holography lasers emit light of a very narrow linewidth. For example, a suitable 532nm green laser might produce 100% of its output power within a slice of the electromagnetic spectrum as narrow as 0.000005 nanometers. A cheap laser pointer will produce light across a much larger portion of the spectrum.

The linewidth and wavelength together define the coherence length of your laser. This defines how far your beam can propagate while staying in phase, or coherent. This is the distance you want to stay within when making holograms. For unstabilised helium-neon lasers, for example, this is typically the length of the resonator (perhaps 20cm). For the Coherent Compass lasers, this can be dozens or hundreds of meters!

While some cheap red laser diodes can produce a usable coherence length, it's much less common for other wavelengths. There are some green and blue laser diodes (in the $50-$100 range) that can feasibly be used for holography with careful power and temperature regulation, but I've not heard of anyone ever producing a hologram with non-red laser pointers purchased off the shelf.

I'm still learning myself, so I trust one of you will call me out if I've said anything incorrect here :)
Zeta
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Re: 1st time on DCG Project

Post by Zeta »

Laser just arrived yesterday. I connect it to power supply but no laser came out just orange light turn on, I wait around 5 minute but still notting.
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holomaker
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Re: 1st time on DCG Project

Post by holomaker »

You may need to wait longer.... put a piece of paper close
And see if you get something, controller sometimes take a little while to wake up! Also do you have a little jumper installed in the 215 controller ?
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admin_jsfisher
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Re: 1st time on DCG Project

Post by admin_jsfisher »

The connector is on the wrong way. 180 degrees off.

ETA: Wait a minute. The beveled side of the connector should be down, which it is, but the cable is coming out the other side. Hmmm. This is very confused.
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admin_jsfisher
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Re: 1st time on DCG Project

Post by admin_jsfisher »

All the ones I have ever seen are like this. Did you rebuild the connector to have the cable exit the top?
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pluto
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Re: 1st time on DCG Project

Post by pluto »

Please make sure everything is hooked up correctly before applying power... you could very easily damage your laser head and/or controller by hooking things up incorrectly. Many people here can advise you on this :)
Zeta
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Re: 1st time on DCG Project

Post by Zeta »

I think it is on the correct side, because the orange light and other red square will block the way. The color arrangement of the wire is also same in the photo
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Yes I also have a small jumper here.
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controller and laser head is a bit hot but still can touch

:? :? May be I need to wait longer.
pluto
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Re: 1st time on DCG Project

Post by pluto »

Zeta wrote:I think it is on the correct side, because the orange light and other red square will block the way. The color arrangement of the wire is also same in the photo
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Yes I also have a small jumper here.
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controller and laser head is a bit hot but still can touch

:? :? May be I need to wait longer.
Zeta, did you make any progress?

I don't have this laser myself, so unfortunately I can't advise you on much.

The laser head will not come on, is that right? What are you using as a DC power supply? Did you confirm the voltage with a multimeter? Give as much info as possible.

I believe that unused port on the controller is an analog interface port -- you may be able to hook up a multimeter and get a fault code. This would be ideal if possible. I believe the digital controller has an RS232 port which you can communicate with via serial console.
pluto
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Re: 1st time on DCG Project

Post by pluto »

D'oh... I'm too used to having a dial and RS232 control on my controller. Of course you're getting no output... you've not programmed the controller via the DB15 (unused in your pic) port. Here is the pinout:

http://www.repairfaq.org/sam/laserscl.htm#sclcpsma

BTW: What are those two wires you have twisted together? Where did you read that you should do this? The link above seems to suggest that it's not a good idea...

Here's what you need to do:

1) Turn the interlock ON - Pin 1 - Connect to pin 11
2) Set the laser power - Pin 13 - 0-5V for 0-100% power, you can connect this to pin 11 as well

Here is the pinout looking into the DB15 connector:

Image

Be careful and good luck!
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