Adaptive CdTe:V photo-EMF detectors for laser ultrasonic detection

摘要

Preliminary results on utilization of CdTe:V photo-EMF detectors for broad-band (≈ 10 MHz) adaptive detection of optical phase modulation, which is necessary for laser ultrasonic applications, are reported. Unlike widely used GaAs photo-EMF detectors, devices under consideration demonstrate no remarkable electron-hole competition and ensure sensitivity necessary for detection of ≈ 2 nm surface displacement for 0.1 mW of signal beam power in simple transverse configuration without utilization of asymmetric interdigitated surface contacts. For the wavelength used (λ = 851 nm) dielectric cut-off frequency of typical CdTe:V detector was around 1 MHz, which, in principle, allows us monitoring of as-processed objects moving with in-plane velocity up to 10 m/s.