Optical Microphone Substrate With Holes For Noise Reduction

The substrate is designed with an array of holes extending through its thickness, transforming it from a solid structure to a porous one. These holes allow acoustic pressure to equalize between the membrane's two sides, eliminating squeeze-film resistance that would otherwise dampen membrane vibration and reduce signal quality. The porous structure maintains structural integrity while improving acoustic performance and signal-to-noise ratio.

The substrate is segmented by introducing multiple discrete holes rather than maintaining a continuous solid structure. This segmentation creates pathways for acoustic pressure equalization while preserving overall structural support. The holes are distributed in a pattern that balances acoustic performance with mechanical strength requirements.

The substrate exhibits local quality variations with a thin first substrate portion and a thicker second substrate portion. The holes are strategically positioned and sized to be small relative to the wavelength of light, making them effectively invisible to the optical path while remaining large enough to provide acoustic equalization. This local differentiation allows simultaneous optimization of acoustic and optical performance.

The substrate design effectively creates optical transparency in the region where holes are present. The holes are dimensioned such that they do not significantly scatter or absorb light at the operating wavelength, maintaining optical transmission while providing acoustic relief. The structural configuration allows light to pass through unaffected by the presence of the holes.

The substrate design transitions from a uniform thin structure to a multi-layered structure with varying thickness in different dimensions. The thin first substrate portion optimizes light transmission for optical performance, while the thicker second substrate portion provides mechanical strength and thermal stability. This dimensional variation allows simultaneous optimization of optical and mechanical properties.

The substrate functions as a composite structure with regions of different thicknesses, effectively combining the properties of thin (high transparency) and thick (high strength) regions. This composite configuration allows the substrate to exhibit both high optical transmission in the light path and sufficient mechanical strength for structural support and thermal noise resistance.

The substrate is segmented into functional zones with different thicknesses - a thin first substrate portion for optimal light transmission and a thicker second substrate portion for mechanical support. This segmentation allows each region to be optimized for its specific function while maintaining manufacturability through standard thin-film deposition and etching processes.

The substrate implements local quality differentiation where the thickness varies spatially to meet different performance requirements. The thin region optimizes optical performance while the thick region ensures mechanical integrity. This local variation can be achieved through controlled deposition or etching processes that create the desired thickness profile during manufacturing.