Hello, this is my first real post, so hello. I have mounted a metal octagon shaped piece from a bicycle headstock onto a DVD drive motor. When I shoot my laser at it while its spinning, I still just get one single dot instead of a line. Can anyone tell me what I need to do differently? Could it be my $3 laser pointer from petsmart isn't strong enough to produce anything but a single point? If anyone is actually interested I can probably get a picture of it. Thank you!
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really simple liquid sky question
- Thread starter TLAZ
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I believe you need to have the mirror mounted at an angle.
This might help
This might help
Maybe you're not spinning it fast enough, or you are missing the octagon with your laser....
It also helps if the spinning thing actually has a mirror-like finish.
Where is your "single point" anyhow? On your wall or on the spinning thing?
Pictures mostly always help.
It also helps if the spinning thing actually has a mirror-like finish.
Where is your "single point" anyhow? On your wall or on the spinning thing?
Pictures mostly always help.
Last edited:
OK I'm pretty sure I figured it out. I think my little red dot is just too weak to do anything cool with, but I mounted the octagon with a small piece of tape under a part of it to make it tilted and when i'm really close to it, it makes a fuzzy red line on my shirt so I am assuming with a lot of smoke and a better laser it would work. Thanks for your help guys!
andy_con
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Cheap laser pointers have such a low output that when you use them for line or circle (or spirograph) effects the reflected output is significantly diminished.
To put it another way : If your single spot or dot of light, for simplicity (PLEASE bear with me everyone who knows better !), measures as 100mw, then a line that is 100 times as long as that little dot will only be perceived as 1mw. You see the connection ? For a increase in size of 100 you get only 100th the ammount of light along each point of that increase in length. A line ten time as long would be 1/10th the brightness. A series of circles that add up to 500 times the length of that original dot would be 1/500th as bright.
In actual fact, you are also losing a lot from the surface you are reflecting from as well. Even the best, most expensive, front sided mirrors lose some of the energy. A lousy reflector could easily waste almost half of your output.
This is why many of the posting here follow the same path. The more that you project or manipulate the beam(s) the higher power those beams need to be.
You never hear of a projection system using a low power laser to make large projected images on a wall or over a crowd. The math tells you that it just isn't possible.
And then the other more obvious point. It is incredibly rare that you pick up a cheap laser pointer from one of those types of places and it has fresh, top of the line batteries in it. Even unopened packs usually have some corrosion on the actual batteries. Rubbing then on a rough paper towel or your pants can change a fairly dim output to an uncomfortably bright one. (If you use your pants, be ready for some mystery holes to appear after a couple of washing though !)
Just my thought though...
To put it another way : If your single spot or dot of light, for simplicity (PLEASE bear with me everyone who knows better !), measures as 100mw, then a line that is 100 times as long as that little dot will only be perceived as 1mw. You see the connection ? For a increase in size of 100 you get only 100th the ammount of light along each point of that increase in length. A line ten time as long would be 1/10th the brightness. A series of circles that add up to 500 times the length of that original dot would be 1/500th as bright.
In actual fact, you are also losing a lot from the surface you are reflecting from as well. Even the best, most expensive, front sided mirrors lose some of the energy. A lousy reflector could easily waste almost half of your output.
This is why many of the posting here follow the same path. The more that you project or manipulate the beam(s) the higher power those beams need to be.
You never hear of a projection system using a low power laser to make large projected images on a wall or over a crowd. The math tells you that it just isn't possible.
And then the other more obvious point. It is incredibly rare that you pick up a cheap laser pointer from one of those types of places and it has fresh, top of the line batteries in it. Even unopened packs usually have some corrosion on the actual batteries. Rubbing then on a rough paper towel or your pants can change a fairly dim output to an uncomfortably bright one. (If you use your pants, be ready for some mystery holes to appear after a couple of washing though !)
Just my thought though...