Fabry Perot Acoustic Sensor With Two-Axis MEMS Mirror Scanning
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Solution Overview
Problem
Current photoacoustic imaging systems are not compact or flexible enough, limiting their applicability and efficiency in various medical and diagnostic applications.
Innovation Solution
A photoacoustic probe head incorporating a Fabry Perot acoustic sensor with a two-axis MEMS mirror for scanning an interrogation beam, coupled with an excitation light source and a light detector, allows for flexible and compact imaging by modulating the interrogation beam in response to acoustic signals, enabling detailed spatial mapping of acoustic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Fabry Perot acoustic sensor with two-axis MEMS mirror is used, then spatial sampling precision and detection sensitivity are improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical scanning systems with a two-axis MEMS mirror that uses electrostatic actuation to deflect the interrogation beam. This substitution reduces mechanical complexity while maintaining high spatial sampling precision through precise electronic control of mirror angles.
Solution Approach 2:
The MEMS mirror enables dynamic scanning of the interrogation beam across the acoustic sensor surface by rapidly changing mirror deflection angles. This dynamic operation allows high-speed spatial mapping without complex mechanical moving parts, improving both precision and reducing structural complexity.
2Adaptability or versatility
If the sensor head is placed directly on the skin surface, then adaptability and ease of operation are improved, but acoustic signal detection capability may be compromised
Solution Approach 1:
The Fabry Perot etalon mirrors are designed with wavelength-specific properties: they are transparent to the excitation laser wavelength (allowing direct skin placement and laser transmission) while being highly reflective at the interrogation beam wavelength (enabling sensitive acoustic detection). This local quality differentiation resolves the contradiction between adaptability and detection capability.
Solution Approach 2:
The patent changes the optical parameters of the etalon mirrors to achieve wavelength selectivity. By tuning the mirror reflectivity at different wavelengths, the system enables both direct skin contact (adaptability) and high-sensitivity acoustic detection (reliability) to coexist.
3Measurement precision
If the element size is reduced to tens of micrometres, then spatial sampling resolution is improved, but detection sensitivity may be reduced
Solution Approach 1:
The patent replaces piezoelectric receivers with optical detection using a Fabry Perot etalon and laser interrogation. This substitution enables high detection sensitivity with small element sizes because optical methods can detect minute acoustic-induced thickness changes in the etalon spacer, overcoming the sensitivity limitations of mechanically-based detectors at small scales.
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
This configuration provides high sensitivity and fine spatial sampling, enabling more compact and flexible photoacoustic imaging systems that can be used in various settings, including transcutaneous, intra-oral, and endoscopic procedures, while maintaining high detection sensitivity and broadband response.
Implementation Method 1
Acoustically induced changes in the optical thickness of the spacer modulate the reflectivity of the etalon, which can be detected by measuring the changes in reflected power of an incident interrogation beam
Implementation Method 2
a two-axis mirror configured to scan the interrogation beam between different locations of the acoustic sensor
Implementation Method 3
In photoacoustic (PA) imaging, acoustic waves are excited by irradiating a sample with modulated electromagnetic radiation
Implementation Method 4
A Fabry Perot acoustic sensor may be used to detect the acoustic waves. Such devices typically employ a polymer film etalon that comprises a polymer film spacer sandwiched between a pair of mirrors
Data Source
AI summary
A photoacoustic probe head (200a, 200b) is disclosed. The probe head (200a, 200b) comprises: a Fabry Perot acoustic sensor (202), an interrogation interface (A), an excitation input (B) and a two-axis mirror (204). The Fabry Perot acoustic sensor (200a, 200b) is operable to reflect an optical interrogation beam to create a reflected interrogation beam and to modulate the reflected interrogation beam in response to an acoustic signal at the acoustic sensor (202). The interrogation interface (A) is configured to receive an interrogation beam, and to receive the reflected interrogation beam from the acoustic sensor (202). The excitation input (B) is configured to receive an excitation beam for generating an acoustic field in a sample adjacent to the acoustic sensor (202). The two axis mirror (240) is configured to scan the interrogation beam between different locations of the acoustic sensor (202).