Local determination of thin liquid film profiles using colour interferometry

Area of Science:

• Optics
• Surface Science
• Thin Film Analysis

Background:

• Optical interference is a phenomenon used to measure thin films.
• Previous methods often used discrete wavelengths, limiting experimental simplicity.
• Understanding interference with broadband light is crucial for practical applications.

Purpose of the Study:

• To theoretically and experimentally investigate white light interference between two interfaces.
• To compare interference patterns generated by discrete wavelengths, Gaussian distributions, and broadband white light.
• To demonstrate the utility of broadband white light for precise separation measurements.

Main Methods:

• Theoretical modeling of optical interference under three different light conditions: discrete wavelengths, Gaussian distributions, and broadband white light.
• Experimental verification using a color camera for detection.
• Analysis of air films and liquid films under various conditions.

Main Results:

• Unfiltered white light provides unambiguous absolute separation information over the 0-1μm range.
• This method is optically simple to implement.
• Experimental validation confirmed the technique's effectiveness for air films and liquid films.

Conclusions:

• Broadband white light interference is a simple and effective method for precise thin film measurements.
• The technique is applicable to studies in cell adhesion, thin liquid films, and lubrication.
• This approach offers a practical alternative to methods using discrete or filtered light sources.