The PLACID fiber optic measurement microphone (POFM-01) enables acoustic measurement in environments where conventional condenser or IEPE microphones cannot be used safely or reliably. Conventional microphones contain electrically conductive components throughout the signal chain — from the metal diaphragm and capsule body to the coaxial cable and preamplifier. In environments with strong electromagnetic fields, explosive atmospheres, or extreme electrical hazards, these conductive elements create measurement problems or safety risks.
The PLACID POFM-01 uses an optical sensing principle: a thin diaphragm at the sensor head modulates the intensity or phase of light transmitted through a fiber optic cable. The light source, detector, and all signal processing electronics are located at the remote control unit, outside the hazardous or high-field environment. The sensor head contains no metal parts, no electronics, and carries no electrical current — making it inherently immune to electromagnetic interference and safe in explosive atmospheres.
The POFM-01 is calibrated by substitution against a reference condenser microphone in a controlled acoustic field. ISO/IEC 17025 accredited calibration is available for all production units. The calibration certificate states the sensitivity at 1 kHz and the frequency response from 20 Hz to 10 kHz with an expanded measurement uncertainty. For applications where measurement uncertainty must be formally documented — for example, in regulatory submissions or quality management audits — the accredited calibration option is recommended.
Contact PLACID to discuss specific application requirements, environmental constraints, and required cable lengths. Custom cable configurations and alternative connector types for the control unit analog output are available on request. Lead time for standard units is 6 to 10 weeks from order confirmation.