High accuracy, wide range, rotation angle measurement by the use of two parallel interference patterns

Area of Science:

• Optical metrology
• Precision engineering

Background:

• Measuring small rotation angles often uses parallel interference patterns (PIPs).
• Existing methods struggle with accurately measuring large rotation angles.

Purpose of the Study:

• To develop a method for accurately measuring large rotation angles.
• To enhance the range and precision of angle measurement techniques.

Main Methods:

• Utilizing two parallel PIPs with distinct periods for angle measurement.
• Combining measurements from a high-accuracy, small-period PIP and a wide-range, large-period PIP.
• Phase detection accuracy is optimized by the choice of PIP periods.

Main Results:

• Accurate measurement of rotation angles ranging from approximately -30 to 30 arc minutes.
• Achieved measurement accuracy of 0.2 arc seconds.
• Experimental validation confirmed analytical predictions.

Conclusions:

• The combined PIP method effectively measures large rotation angles with high accuracy.
• This technique offers a significant improvement over existing angle measurement methods.
• The study demonstrates the feasibility and efficacy of the proposed measurement approach.