#20 - Geometric measurements - Lens

🔍 Lens selection for geometric optical measurement – why is it critical?

In geometric measurement systems, the lens’s role is to project the real-world scene onto the camera sensor. The accuracy of the measurement is heavily influenced by the type of optics we choose.

🔎 Magnification
⤷ Determines how many millimeters correspond to 1 pixel on the sensor
⤷ Magnification + camera resolution together define the measurement resolution and the visible area (FOV)

🔎 Depth of Field (DOF)
⤷ The range in which the image remains sharp
⤷ Even within the DOF: objects closer to the lens appear larger → this can introduce geometric error

🔎 Telecentric lenses
⤷ Provide the same measured size for objects at different distances (within the DOF range)
⤷ Industrial advantage: distortion-free dimensional measurement
⤷ Drawback: larger physical size and higher cost

Choosing the right optics is one of the most important aspects of geometric measurements — in the next post, we’ll continue with the camera system.

Download GeomOptMeasLens.pdf