Remote displacement sensing by decoupling a compact sensing head from a heterodyne Michelson interferometer

Area of Science:

• Optical Metrology
• Precision Measurement

Background:

• Interferometric displacement sensors require careful optical design for noise resistance and compactness.
• Existing sensors often lack the necessary sensitivity or compactness for advanced applications.

Purpose of the Study:

• To develop a highly sensitive and compact interferometric displacement sensor.
• To demonstrate a versatile sensor design using off-the-shelf components.

Main Methods:

• Designed a heterodyne Michelson interferometer with a decoupled sensing head.
• Utilized a single fiber optic link to carry both test and reference beams.
• Achieved a compact sensing head with only three optical components.

Main Results:

• Achieved displacement sensitivity below 1 picometer per root Hertz (pm/√Hz) between 3 Hz and 800 Hz.
• Demonstrated a compact sensing head suitable for various applications.
• Validated the sensor's performance and discussed its limiting factors.

Conclusions:

• The developed sensor offers unparalleled sensitivity and compactness.
• The design is versatile and can be built using readily available components.
• Suitable for spacecraft, seismometers, and gravitational-wave detector feedback systems.