Scanning technique for obtaining linear fringe shift readout from a high resolution interferometer

Area of Science:

• Optics and Photonics
• Interferometry
• Measurement Science

Background:

• Fabry-Perot interferometers are crucial for high-resolution spectral analysis.
• Traditional fringe shift readout methods can be ambiguous and dependent on interferometer finesse.
• A need exists for a simplified, robust, and unambiguous fringe shift measurement technique.

Purpose of the Study:

• To develop a technique for obtaining a linear readout of fringe shift from a high-resolution Fabry-Perot interferometer.
• To demonstrate that this readout is unambiguous and independent of interferometer finesse.
• To utilize standard laboratory equipment for the measurement process.

Main Methods:

• One mirror of the Fabry-Perot interferometer is mounted on a piezoelectric crystal driven by a high-frequency sinusoidal voltage.
• Mirror displacement is displayed on an oscilloscope's Y-axis, while the X-axis is time-swept.
• Pulses generated at transmission maxima are fed to the oscilloscope's Z-axis, creating intensified dots.

Main Results:

• A row of intensified dots is produced on the oscilloscope display.
• The displacement of these dots from their ambient position is linearly proportional to the fringe shift.
• The technique provides an unambiguous readout independent of the interferometer's finesse.

Conclusions:

• The described technique offers a linear, unambiguous, and finesse-independent readout of fringe shift.
• The method effectively utilizes the internal circuitry of a standard laboratory oscilloscope.
• This approach simplifies fringe shift measurement in high-resolution Fabry-Perot interferometry.