Scanning laser differential-heterodyne interferometer for flying-height measurement

Area of Science:

• Optical Engineering
• Tribology
• Data Storage Technology

Background:

• Conventional optical interferometry for flying-height testing relies on stationary beams and moving stages.
• This method calculates pitch or roll angles from discrete measurements of slider-disk spacing.
• Limitations exist in capturing continuous flying-height variations with traditional techniques.

Purpose of the Study:

• To introduce and demonstrate a scanning differential-heterodyne interferometer for measuring flying height.
• To enable direct and continuous measurement of flying-height variation along a slider's edge.
• To compare scanning measurement results with conventional methods.

Main Methods:

• Utilizing two continuously scanning laser beams for differential-heterodyne interferometry.
• Implementing a system capable of both continuous scanning and individual point measurements.
• Performing experimental validation of the scanning measurement concept.

Main Results:

• Continuous flying-height variation along the slider edge was successfully measured.
• Pitch and roll angles were obtained directly from the scanning measurement data.
• Experimental results from continuous scanning correlated well with conventional measurement techniques.

Conclusions:

• The scanning differential-heterodyne interferometer provides an effective method for measuring continuous flying-height variations.
• This technique allows for direct determination of pitch and roll angles.
• The system demonstrates accuracy comparable to conventional methods while offering enhanced measurement capabilities.