Determination of thin hydrodynamic lubricating film thickness using dichromatic interferometry

Area of Science:

• Tribology and Lubrication Science
• Optical Metrology
• Fluid Dynamics

Background:

• Conventional interferometry methods for lubrication studies often involve static objects or sequential beam projection.
• Existing techniques like monochromatic and chromatic interferometry have limitations in studying dynamic lubrication phenomena.
• Hydrodynamic lubrication is critical in mechanical systems, requiring accurate real-time thickness measurements.

Purpose of the Study:

• To introduce and evaluate dichromatic interferometry for studying hydrodynamic lubrication under dynamic conditions.
• To demonstrate the capability of simultaneous dual-color laser projection for interference imaging in lubrication.
• To compare the advantages of dichromatic interferometry over conventional methods for lubrication research.

Main Methods:

• Simultaneous projection of two lasers with different colors onto hydrodynamic lubricated contacts under running conditions.
• Formation of interference images using the dual-color laser setup.
• Static evaluation by measuring wedge film inclination and dynamic evaluation by measuring hydrodynamic lubricating film thickness.

Main Results:

• Dichromatic interferometry successfully measured the inclination of static wedge films.
• The method accurately determined hydrodynamic lubricating film thickness under running conditions.
• Real-time determination of lubricating film thickness was achieved.

Conclusions:

• Dichromatic interferometry offers a significant advancement for lubrication research, combining benefits of monochromatic and chromatic methods.
• The technique is well-suited for the real-time study of transient and dynamic lubricating problems.
• This method facilitates a deeper understanding of lubrication dynamics in operational environments.