DESCRIPTION:

This invention involves a differential microphone that utilizes an optical means of converting the sound-induced motion of the diaphragm into an electronic signal. The majority of high-performance microphones, and particularly miniature microphones used in cellular telephones and hearing aids, use capacitive sensing to detect the diaphragm motion. This involves detecting the change in capacitance between the pressure-sensitive diaphragm and a back plate electrode. In order to detect this change in capacitance, it is first necessary to impose a bias voltage between the back plate and the diaphragm.

This voltage creates practical constraints on the mechanical design of the diaphragm that compromise its effectiveness in detecting sound. The aim of this invention is to overcome these performance limitations by the use of an optical detection scheme. The optical detection scheme uses a low-power semiconductor laser and optical gratings incorporated into the microphone diapbgm, Because the overall compliance of the microphone diaphragm is adjustable over a very wide range, it is possible to achieve high sensitivity and very low noise.

POTENTIAL APPLICATIONS:

Hearing aid applications and high-performance microphones.

ADVANTAGES:

It permits the use of much more flexible diaphragms. It also enables the use of much smaller diaphragms than it is currently possible. Lower noise floor.

DISADVANTAGES:

It may cost more.

PATENT STATUS:

Patent pending.