Optical Transducer Lens Beam Divergence
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Solution Overview
Problem
Current capacitive transducers in consumer electronics, such as microphones, face limitations in achieving high sensitivity and low noise, particularly in emerging applications like voice recognition and deep learning that require an increased signal-to-noise ratio.
Innovation Solution
An integrated optical transducer using an interferometric readout of a mechanically compliant diaphragm with a lens element to correct for beam divergence, ensuring high sensitivity and minimal optical losses, comprising a MEMS diaphragm, waveguide structure, coupling element, and photodetector, which forms an optical interferometer like a Mach-Zehnder or Michelson interferometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive readout is used in MEMS transducers, then the device is sufficient for high-end audio applications, but the signal-to-noise ratio is insufficient for voice recognition and deep learning applications
Solution Approach 1:
The patent replaces the capacitive readout mechanism with an optical interferometric readout system. This substitution uses optical fields instead of electrical fields to measure diaphragm displacement, achieving higher sensitivity and signal-to-noise ratio required for voice recognition and deep learning applications while maintaining transducer reliability
2Loss of energy
If an optical interferometer is implemented without a lens element, then the structure is simpler, but beam divergence causes significant optical losses
Solution Approach 1:
The patent introduces a lens element as an intermediary component in the optical path between the coupling element and the diaphragm. This lens collimates the divergent light beam, ensuring that light reflected from the diaphragm surface is efficiently coupled back into the waveguide, thereby minimizing optical losses while maintaining a practical system structure
3Length of moving object
If the diaphragm is placed close to the substrate body, then the device size is reduced, but the optical path length is insufficient for effective interferometric measurement
Solution Approach 1:
The patent utilizes the third dimension (vertical spacing) by positioning the diaphragm at an optimized distance from the substrate body. This creates sufficient optical path length for effective interferometric measurement while maintaining a compact overall device volume, achieving both measurement accuracy and miniaturization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a high sensitivity measurement of diaphragm displacement with negligible optical losses, enhancing the signal-to-noise ratio and enabling efficient detection of dynamic pressure changes, particularly in audio frequency ranges.
Implementation Method 1
The waveguide structure is configured to guide light from a light source to the coupling element and from the coupling element to a photodetector
Implementation Method 2
The coupling element is configured to couple at least part of the light in the waveguide onto a light path between the coupling element and the diaphragm and to couple light reflected by a surface of the diaphragm from the light path into the waveguide structure
Implementation Method 3
The lens element is arranged on the light path such that light on the light path passes through the lens element
Implementation Method 4
ensuring a high efficiency and minimal loss of the optical readout scheme
Implementation Method 5
to couple light reflected by a surface of the diaphragm from the light path into the waveguide structure
Implementation Method 6
interferometric readout of a displacement of a mechanically compliant object, such as a diaphragm
Data Source
AI summary
An integrated optical transducer for measuring displacement of a diaphragm comprises the diaphragm, a lens element and a substrate body having a waveguide structure and a coupling element. The diaphragm is arranged distant from the substrate body and substantially parallel to a main extension plane of the substrate body. The waveguide structure is configured to guide light from a light source to the coupling element and from the coupling element to a photodetector. The coupling element is configured to couple at least part of the light in the waveguide structure onto a light path between the coupling element and the diaphragm and to couple light reflected by a surface of the diaphragm from the light path into the waveguide structure. The lens element is arranged on the light path such that light on the light path passes through the lens element.