Method and device for evaluating a mechanical property of a material

Inventors

Kennedy, Brendan • WIJESINGHE, Philip

Assignees

University of Western Australia • Oncores Medical Pty Ltd

Abstract

The present disclosure provides a method of evaluating a mechanical property of a material using a device for evaluating the mechanical property of the material. The device comprises a sensing layer having a thickness, a sensing surface and an opposite surface. The sensing layer is deformable such that, when the sensing surface is in direct or indirect contact with the material and a suitable load is applied across both the sensing layer and at least a portion of the material, the sensing layer deforms and the sensing surface moves relative to the opposite surface. The device also comprises a source of electromagnetic radiation in optical communication with the sensing layer. The source is arranged for generating electromagnetic radiation having a coherence length that is of the same order of magnitude as the thickness of the sensing layer or longer than the thickness of the sensing layer. Further, the device comprises a detector for detecting the electromagnetic radiation and being in optical communication with the sensing layer and arranged for receiving the electromagnetic radiation after the electromagnetic radiation is reflected at the interface at the sensing surface of the sensing layer. The method comprises positioning the sensing layer relative to the material such that the sensing surface is in direct or indirect contact with the material. Further, the method comprises applying the suitable load across both the sensing layer and at least a portion of the material whereby the sensing layer deforms and the interface at the sensing surface moves relative to a condition in which no load is applied. The method also comprises directing the electromagnetic radiation to the interface at the sensing surface such that at least a portion of the electromagnetic radiation is reflected at the interface at whereby a first signal is generated and directing electromagnetic radiation along a second optical pathlength to generate a second signal. Further, the method comprises allowing the first signal and the second signal to interfere and detecting an intensity associated with a resultant interference signal using the detector; and determining information concerning the mechanical property of the material from the detected intensity of the interference signal.

Core Innovation

The invention provides a method and a handheld device for evaluating a mechanical property of a material using optical palpation with a deformable sensing layer. The sensing layer has a thickness, a sensing surface and an opposite surface, and it deforms such that, when the sensing surface is in direct or indirect contact with the material and a suitable load is applied across both the sensing layer and at least a portion of the material, the sensing surface moves relative to the opposite surface.

Electromagnetic radiation is directed to an interface at the sensing surface so that reflected light generates a first signal while light along a second optical path generates a second signal. The method and device use interference between the first and second signals to detect an intensity associated with a resultant interference signal, and information concerning the mechanical property is determined from the detected intensity, including information concerning relative interface movement and/or a change in an optical pathlength difference between the first and second signals.

The source of electromagnetic radiation is arranged to generate radiation having a coherence length that is of the same order of magnitude as the thickness of the sensing layer or longer than the thickness of the sensing layer, so that the detector can detect interference from reflections associated with the sensing layer interfaces. The disclosed arrangements include detecting reflections associated with top and bottom interfaces of the sensing layer, and using polarization-diversity detection with polarisation controllers/filters and a polarising beam splitter to detect polarization-specific signals and reduce sensitivity to tilt/focus in an interferometric intensity measurement.

Claims Coverage

The document includes two independent claims: one method claim and one handheld device claim. Together they cover an optical interferometric mechanical-property evaluation using a deformable sensing layer, a coherence-length constraint relative to sensing-layer thickness, and determination of mechanical-property information from interference intensity derived from first and second optical pathlength signals.

Across the independent claims, the inventive core combines a deformable sensing layer that moves under a suitable load with an interferometric measurement using a coherence-length constraint relative to the sensing-layer thickness. Mechanical-property information is determined from interference intensity derived from signals associated with first and second optical pathlengths.

Stated Advantages

Documented Applications