How Do You Calculate Cylinder Rotation Using Laser Reflection?

What does that tell us about the angle between the laser beam and the cylinder?In summary, the problem involves measuring the rotation of a vertical cylinder using an optical lever with a laser and a mirror. The reflected laser beam is deflected to the side by 2 mm, and by using arctan (0.002/5) and dividing by 2, we can calculate the rotation angle of the cylinder. This is because the angle between the normal and the laser beam is equal to 2 times the angle between the laser beam and the cylinder.
  • #1
dorkenstine00
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Homework Statement


You're helping with an experiment in which a vertical cylinder will rotate about its axis by a very small angle. You need to devise a way to measure this angle. You decide to use what is called an optical lever. You begin by mounting a small mirror on top of the cylinder. A laser 5 m away shoots a laser beam at the mirror. Before the experiment starts, the mirror is adjusted to reflect the laser beam directly back to the laser. Later, you measure that the reflected laser beam, when it returns to the laser, has been deflected to the side 2 mm. Through how many degrees has the cylinder rotated?


Homework Equations





The Attempt at a Solution


So I understand the part about solving for arctan (0.002/5)
I know to get the solution, this needs to be divided by 2. I know its probably some simple geometry that I'm lacking, but I can't figure out why the angle here is 2theta and not just theta. Thanks in advance for the help!
 
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  • #2
Think about the laser beam and the mirror. What do we know about the angle between the normal and the laser beam?
 

FAQ: How Do You Calculate Cylinder Rotation Using Laser Reflection?

What is laser reflection?

Laser reflection is the process of a laser beam bouncing off a surface, following the law of reflection, which states that the angle of incidence (incoming beam) is equal to the angle of reflection (outgoing beam).

How does the angle of incidence affect laser reflection?

The angle of incidence determines the angle at which the laser beam will reflect off the surface. If the angle of incidence is perpendicular to the surface, the beam will reflect back in the same direction. If the angle of incidence is at an angle to the surface, the beam will reflect at an equal angle in the opposite direction.

What is the difference between specular and diffuse reflection in laser beams?

Specular reflection occurs when the surface is smooth and the laser beam is reflected at the same angle. Diffuse reflection occurs when the surface is rough and the laser beam is scattered in multiple directions.

How is the angle of reflection measured in laser reflection?

The angle of reflection is measured between the reflected beam and the normal line, which is an imaginary line perpendicular to the surface at the point of reflection.

What factors affect laser reflection?

The factors that affect laser reflection include the angle of incidence, the surface material and texture, and the wavelength of the laser beam. The type of laser and its power can also play a role in the reflection of the beam.

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