Mon 23 Oct 2006
Posted by brain under Photography
, TechnologyComments Off on Laser Photography
A few weeks ago I did some photography of skulls using a laser. After that experiment my friend Vern and I started talking about putting the laser on two servos and making it computer controlled. He built an apparatus for me in a surprisingly short time.
He mounted a $ store laser to a servo to control tilt and mounted that servo to another one to control pan. Simple. He hooked both of these up to a basic stamp controller and mounted them to a board. Then wrote code to make the laser sweep side to side and up and down.
I took the code he sent me made some modifications and did the first test. You can see from the hires version that it looks like the laser is sweeping past each line twice. I'm not sure why this is.
On the second test I decreased the vertical step so that the lines are closer together and the exposure is longer.
For the third test I made the lines really close together to almost bathe the scene in laser light.
Now I decided it was time to turn it into a grid. So I rewrote the code to sweep left to right while moving top to bottom. Then to switch directions and move top to bottom while sweeping right to left.
The grid came out more regular than I had expected.
For the last test of the evening I just tightened the grid up.
If you are curious here is what the scene looked like with the lights on and with the laser sweeping. You will notice in all the photos that there is a red light on the left hand side. That light is the laser.
Here is the Basic Stamp Code that made the grid.
Wed 18 Oct 2006
Posted by brain under Rant
, TravelComments Off on Nomad
I want to be a nomad for a while. I want to travel.
Tyler Durden said something about the things you own owning you, which is true. The odd thing is that you don't really own them. Like all things in life it is an illusion. Quit paying taxes on your home and see how long you 'own' it. Quit paying to store your things and soon they are gone.
So this year we decided to purge everything we have. (Well except the things we are actually using.) Attachment to things is hard to give up. I have done pretty well with it in my life. Over the years I have lost everything I have at least 3 times. So I like to think that I don't really have attachment. Rather I like to think that I just have stuff and it's good while its here. If it were gone, I wouldn't be too upset.
But how do you get rid of those things that have memories attached? Easy. Take a photo that will serve as a token of that memory. Here is an example. We had a kitty who was getting very sick and we had to give him fluids. Somehow we kept the bag that the fluid came in for years. Now when I look at it, I remember the kitty. Should I get rid of it? Of course. But how will I have that same memory when I look at the bag? Take a picture. They store much easier and have the same token effect on memory. Now I am free to dispose of the bag. It helps that I am a decent photographer and can take pretty good photos of the items before they are gone.
Wondering just how much stuff we have? Take a look at this. This is one of our caches of stuff. We call this room 'the inventory room.' Then plan is to get rid of everything either by listing it on ebay, craigslist, local paper, garage sale, giving it to goodwill, or throwing it away. Not an easy task at all.
The only things that we don't plan on purging are the things that we actively use, our artwork, and our books.
Wed 4 Oct 2006
My cat likes to chase a laser pointer. While I was playing with him the other day I ran the laser point across a poster that I made hanging in my living room. I noticed that as the spot passed over black areas of the poster the light reflected back dimmed and over a lighter area the reflectivity increased. I discovered something that people had discovered thousands of years ago. That different materials absorb light differently. Not a big thing, I know.
But this gave me an idea. What if I were to do a long exposure on a camera as I swept the pointer back and forth. It should make a series of lines of varying widths. That might look neat. I decided to give it a try.
I guessed the best way would be to build something to hold the laser and sweep it past the object while moving it up and down. A screw seemed like the perfect way to do this. As it sweeps past the object it lowers automatically. I never did come up with a way to make the pointer sweep left to right while moving down. Gravity kept interfering. What I did come up with was mounting the screw horizontally so that the pointer sweeps top to bottom and moves left to right.
At the hardware store I picked up a threaded rod and some washers. This one is 5/8" diameter. I built my light kit (which I will explain later in another post) into a simple cube with a place to hold two ends of the screw. On one end of the screw I put a mounting to hold the laser pointer and on the other a place to attach a hand drill.
For my first test I used a alien skull I had sitting on a shelf. The skull doesn't really have areas that bring out the absorbing light that originally attracted me to this project but it does have a nice 3d shape.
The photos of the first pass and the second one came out a little dark so I had to enhance them. The results are good.
Next I want to try mounting a laser pointer on a computer controlled thingy. My friend Vern says he can build a device that can position the laser pointer given an X and Y position. He will build it using two servo motors and a basic stamp processor. This will allow me to do things like sweep a grid pattern over an object while doing the long exposure.
I hope the photos from the next one come out looking as groovy as these did.
The first test image:
The second test image: