Transparency measurement of thin films with one-sided optical access using fluorescence imaging

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Traditional optical transparency measurements require access to both sides of a sample.
• Restricted optical access can hinder accurate transmittance determination in various applications.

Purpose of the Study:

• To present a novel, one-sided optical technique for measuring the transmittance of thin-film objects.
• To demonstrate the technique's applicability in situations with limited optical access.

Main Methods:

• The method involves mounting the object on a fluorescent substrate.
• Illumination at an excitation wavelength and detection of fluorescence emission at a different wavelength.
• Utilizes optical filtering to eliminate reflected excitation light, ensuring accurate fluorescence detection.

Main Results:

• The developed technique achieved measurement differences of 2.4% or less compared to conventional two-sided transmittance measurements.
• Successfully measured the transmittance of neutral density filters and paper during drying.
• Inferred paper moisture content during drying, showing spatial correlation with dryer fabric structure.

Conclusions:

• The one-sided optical transparency measurement technique is a viable and accurate alternative for samples with restricted access.
• This method has practical applications, such as monitoring material properties like moisture content in real-time during manufacturing processes.