Defocused Speckle Imaging for Remote Surface Motion Measurements
Speaker: Dr. Juuso Heikkinen, Digital Holography Researcher at Angstrom Vision Inc., alumnus of the UBC Renewable Resources Laboratory.
Dr. Heikkinen is the 2022 recipient of the Martha Salcudean Prize in Mechanical Engineering, and will present a seminar on research from his winning dissertation.
Location: CEME Building (6250 Applied Science Lane), room 2202
Abstract:
Defocused Speckle Imaging (DSI) is an optical method where a laser source illuminates a rough object surface, and a defocused camera records the scattered light. The resulting image contains a speckle pattern that appears to move if the object displaces or rotates. Surface motion can thus be determined by tracking speckle movements. DSI is attractive for remote measurements because its sensitivity increases with measurement distance. The effective recording distance can be changed by simply defocusing the camera on purpose.
This research presents a simple geometric model to describe DSI characteristics and proposes an arrangement that uses a combination of two cameras focused at different distances. Such setup can measure surface displacements and rotations simultaneously, and also extract important calibration parameters without additional sensors. The experimental demonstration shows that the method can measure microscopic surface movements, object distances and surface angles from tens of meters away at high accuracy and repeatability.
The research findings pave way for building low-cost and simple yet powerful sensors that can be described as a hybrid between a laser pointer and an optical computer mouse. Such sensors can record crucial geometric information about a moving object and its surrounding environment in various fields, like factory automation, human-computer interaction, augmented reality, robotics, and self-driving cars.
Biography:
Juuso Heikkinen received his PhD in Mechanical Engineering at The University of British Columbia, Canada, in 2021 under the supervision of Professor Gary Schajer. In his PhD thesis, Juuso developed a non-contact inspection tool that can remotely measure object distance, relative surface angles and microscopic surface motions from tens of meters away. He received his B.Sc. and M.Sc. in Engineering Physics from Tampere University of Technology, Finland, in 2013 and 2016, respectively. His research interests include interferometry, speckle metrology, and techniques for dimensional and deformation measurements.