The brightness of the line is reduced as the same laser power is distributed over a longer line.This is a geometric principle known as the “intercept theorem”. The line will be short close to the surface and become longer as the distance to the surface increases.The overall length depends on the distance to the surface.
The laser line starts directly below the housing and continues with nearly consistent brightness until the end of the line.
There is no label on my pointer so I will use 655mn for my wavelength. For example red laser pointers have a typical range between 630 nm – 680 nm. If there is no label then you can use typical values. Hair width = (Laser Wavelength * distance to wall) / (width of center pattern * 1/2)įor the Laser Wavelength look at the label on the side of the laser pointer. Now for a little math! Here’s the equation: My laser pointer has a button that you have to keep pressed so I used a wooden cloths pen.
#Point measure laser how to#
You’ll also need to figure out how to keep the laser pointer turned on without touching it.
There are lots of ways to secure the laser pointer. We need to mount or secure the laser pointer so that it is level and steady. We can then measure “w” and solve the above equation for “d” to find the width of the hair.
If we replace the double slit with a strand of hair then light waves will wrap around the hair and interfere in the same way as the double slit setup.