Thickness measurement system for transparent plates using dual digital versatile disc (DVD) pickups

Area of Science:

• Optics and Photonics
• Metrology
• Materials Science

Background:

• Accurate thickness measurement of transparent materials is crucial in manufacturing and quality control.
• Existing methods can be costly or lack the required precision for thin films and plates.
• Developing cost-effective, high-precision metrology tools remains an active area of research.

Purpose of the Study:

• To propose and validate a novel, low-cost, high-precision thickness measurement system for transparent plates.
• To leverage readily available components, specifically dual digital versatile disc (DVD) pickups, for optical metrology.
• To develop a mathematical model for thickness determination based on optical principles.

Main Methods:

• Utilizing two DVD pickups as a laser transmitter and a receiver system.
• Placing the transparent plate in the optical path to modulate the laser beam.
• Measuring the change in the focusing error signal (FES) at the receiver.
• Developing a geometric optical method-based mathematical model for thickness calculation.

Main Results:

• The proposed system successfully measures the thickness of transparent plates.
• Experimental validation demonstrated a high accuracy of 1.5 micrometers.
• The estimated uncertainty for a 150 micrometer measurement was +/-1.37 micrometers.

Conclusions:

• The dual DVD pickup system offers a viable low-cost solution for high-precision thickness measurements.
• The geometric optical method, utilizing FES, provides a reliable basis for the measurement model.
• This technology has potential applications in industries requiring precise metrology of transparent materials.