Topics

1

Lasers / 200mW DPSSFD Labby not behaving well to modulation

« on: November 24, 2009, 03:57:31 pm »

G'Day, yeah I just had to say it some time, everyone expects that.

Anyway I have a 200mW 532 Lab laser that doesn't modulate very well, I know this is like the post before, but this laser does have analog modulation input. It does work, but not very well. If I apply 5 volts to the modulation input it goes to full power but only after about a minute.

To me this seems like the TEC might be faulty and it is either the 1064 heating the FD or the 808 hitting the YAG causing the heating.

Now I am asking all this because I am planning on disassembling it to check it out, but before I do I though I should check.

If I modulate it it responds OK up until just before half way (~2.5V), then it dips a bit, then it blast up to full power. This is using a slow ramp (over 1 second or so).

If it is quickly modulated (like in a laser image), it is ok down low, but flat spots in the middle, and won't do full power on the peaks.

When run continuously with 5V on the modulation input it does get to 200mW.

2

Other Hardware / Analog laser shunt modulation

« on: November 21, 2009, 02:55:30 am »

Hi everyone. I have been busy buying red and violet lasers off eBay. As a consequence, I have found that the LM317 laser supplies are fine for driving the lasers, but when it comes to blanking and ramps they are of course useless.

So, I am designing an analog shunt modulator for these supplies that has a fast response. I have simulated the circuit and it seems to have a delay of about 1 microsecond, and it is very linear with an expected input of 0-5 V (of course). You can adjust the maximum power and blanking points. The circuit is very simple and I will post it if anyone is interested (once I have determined that it doesn't destroy the laser diodes).

Anyway, I have tested it's blanking with my laser driver software and it is awesome (as far as blanking response anyway), I have attached an image of Quisp being scanned with a 650nm 200mW diode I bought from eBay.

I have to apologize about the laser spill, I had to focus the laser on the wall and that made the spot a little too large for the scanner mirrors, I will have to do something about the optics with these cheap lasers to get the spot smaller on the mirrors (maybe a beam expander will work), and this is with a glass collimating lens.

I will post some images with gradients as well when I get a chance.

So here it is, a $49 300mW laser diode (running at 200mW, measured with a coherent power meter). Plus about $10 worth of parts for the modulator.

3

LaserBoy !!! / 3D Shader

« on: November 06, 2009, 06:06:02 pm »

Hey James, where in the code do I find your 2D projection. You know the part that takes the 3D points that have been rotated, zoomed etc, and converts them to 2D points for display on the screen.

I am just about to start working on that in my software, and believe it or not I can't find many examples on the net. I believe because that is usually done by shaders in the graphics cards GPU.

Am I correct in assuming that the x and y points simply get scaled by the z depth. That is how I was going to start to tackle it anyway (assuming the camera is directly pointing back along the z axis).

4

LaserBoy !!! / Delayed Blanking

« on: October 31, 2009, 09:32:15 pm »

Hi there. I am designing a show control system and have just completed the ILDA file parser and mapping component. However when I display the ILDA files that I have downloaded from here the blanking seems to be off by one dot. So the files display the retrace lines. Maybe I am doing something incorrectly.

Also the colors look incorrect, I have implemented the default 256 color table, but it would seem these files require a different table, is there some standard?

PS:

I agree that the ILDA standard for True Color is silly, I have implemented a routine that checks for the LaserBoy proposed version, and the ILDA version, and so far can switch between both quite happily.