1. Idea of Metrology
Su-Jin Kim
2012

2. Energy of light
E =h c/λ = h f
Laser sorce: He-Ne laser, Laser diode

3. Laser mirror detector
Security, Count N people passing a door, Part exist or not
Machine tool workpiece size and coordinate
Milling tool length, diameter, wear
Protect worker from press machine (safety)

4. Velocity of light c = 3x108 m/s
CPU: f=3GHz  Resolution = c(m/s) / f(/s) = 0.1 m
Not accurate. Long distance (Earth to moon by high power laser)
Sound wave v = 300 m/s
CPU: f=3GHz  Resolution = v(m/s) / f(/s) = 1 μm
Fishing, depth of ocean, Seed in metal is very fast. Ultra sound is used to know inside of earth. x

5. Triangle method a l b
x, y , z

6. Interfere Laser is electro magnetic wave with single wave length.
Wave length of laser light: λ=1μm
f = c / λ = 3x108 m/s / 10-6 m = 3x1014 Hz
Resolution: 0.5μm ~ 0.05μm

7. Angle Encoder: Scale is printed on the glass
Light pass and stop at each scale grid.
Encoder is used for the feedback servo motor rotated angle.