Adaptive interferometry with photorefractive crystals

Abstract

This work presents a review of progress and development in the field of adaptive laser interferometry. This method enables highly precise and reliable measurement of various physical parameters under unstable environmental conditions, which makes it very attractive for numerous industrial applications.

Multi-Channel Adaptive Interferometers Based on Dynamic Hologram Multiplexing

“…The last case is considered as most efficient for providing a linear regime of phase demodulation in the adaptive interferometer based on a dynamic hologram recorded in PR crystal in diffusion mode, i.e. without application of external electric field (Kamshilin, et al, 2009). …”

“…Thus, formation of 10 channels in one sample of CdTe crystal leads to doubling of rel  while for another sample of same crystal this increase amounts to just 23%. Taking into account the extremely high sensitivity of an adaptive interferometer which approaches that of classical interferometer (Kamshilin, et al, 2009), one can conclude that even a reduction of sensitivity by a factor of two can be considered as not significant and remains acceptable in most practical applications. Additionally mutual influence of multiplexed channels can be diminished by reduction of the degree of signal beams overlap h (see Eq.…”

Resonance Micro-Weighing of Sub-Picogram Mass with the Use of Adaptive Interferometer

“…Alternatively an interferometer can be implemented with use of dynamic hologram (DH) recorded in a photorefractive crystal (PRC). Due to adaptive properties of DH such an interferometer can stably operate in industrial environment and with light waves having complicated wavefronts [6,7].…”

Registration of acoustic emission in composite material by fiber-optic sensors based on adaptive interferometer

“…Fiber-optic sensors have a high linearity of the amplitude-frequency response and electromagnetic noise protection. Fiber-optic sensors on Bragg diffraction gratings are widely used [5,6]. In view of the high sensitivity of the sensors, their main application is the measurement of stresses and deformations similar to localized strain gauges or piezoelectric sensors.…”

“…The functioning of sensors is based on the interaction of laser radiation beams on a dynamic hologram, which is formed in a photorefractive crystal. The high sensitivity of the measuring system is achieved when two basic approaches are realized: ensuring the exact matching of the wavefronts of the reference and object light beams and maintaining the necessary phase difference between the interfering waves [6].…”