Measuring picometre-level displacements using speckle patterns generated by an integrating sphere

Morgan Facchin; Graham D. Bruce; Kishan Dholakia

doi:10.1117/12.3002080

13 March 2024 Measuring picometre-level displacements using speckle patterns generated by an integrating sphere

Morgan Facchin, Graham D. Bruce, Kishan Dholakia

Proceedings Volume PC12901, Complex Light and Optical Forces XVIII; PC1290108 (2024) https://doi.org/10.1117/12.3002080
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

Numerous areas of photonics including optical microscopy, semiconductor analysis and lithography and fundamental science increasingly aim for precision at or below the nanoscale. As a result, the ability to perform sub-nanometric displacement and position sensing is highly desirable. We demonstrate that the speckle patterns generated by multiple reflections of light inside an integrating sphere provide an exceptionally sensitive probe of displacement. We use an integrating sphere divided into two independent hemispheres, one of which is free to move in any given direction. The relative motion of the two hemispheres produces a change in the speckle pattern from which we can analytically infer the amplitude of the displacement. Our approach results in a noise floor of 5 pm/ Hz (λ /160, 000) above 30 Hz in a facile implementation, which we use to measure oscillations of 17 pm amplitude (λ /50, 000) with a signal to noise ratio of 3.

Conference Presentation

Citation Download Citation

Morgan Facchin, Graham D. Bruce, and Kishan Dholakia "Measuring picometre-level displacements using speckle patterns generated by an integrating sphere", Proc. SPIE PC12901, Complex Light and Optical Forces XVIII, PC1290108 (13 March 2024); https://doi.org/10.1117/12.3002080

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