Comparison of the advantages and disadvantages of optical measurement and contact measurement

Optical measurement and contact measurement are the two main methods of precision measurement. This article conducts a comparative analysis in terms of accuracy, speed, and applicable scenarios.

Optical measurement

Optical measurement (such as image measuring instrument, flash measuring instrument) collects the image of the workpiece through the camera and uses software analysis to complete the measurement.

Advantages:

• Non-contact measurement, will not damage the workpiece surface
• Fast measurement speed, suitable for batch testing
• Can measure soft and easily deformed workpieces
• Simple operation, low requirements on operators

Disadvantages:

• Largely affected by workpiece surface cleanliness and reflection
• Difficulty measuring internal features such as deep holes and grooves
• The measurement accuracy of edge contours is affected by imaging quality

Contact measurement

Contact measurement (such as roughness profile meter, three-dimensional, roundness meter) is measured by contacting the stylus or probe with the surface of the workpiece.

Advantages:

• High measurement accuracy and good stability
• Measuring deep holes and internal features
• Not affected by the color and reflection of the workpiece surface

Disadvantages:

• Contact forces may damage soft workpiece surfaces
• The measurement speed is slow and not suitable for large-scale full inspection.
• The stylus/probe needs to be calibrated and replaced regularly