A non-contact surface roughness measurement technique is put forward based on texture analysis of the digital laser
speckle pattern coming from a measured grinding surface. The speckle pattern was captured by a digital camera while
the grinding metal surface was illuminated by a laser. Then the surface roughness information immerged in the high
frequency sub-band of the speckle pattern was extracted with the texture analysis of wavelet transform and Markov
Random Fields model. Our research has illustrated that surface roughness Ra has a good monotonic relationship with the
texture features of the speckle pattern. If this measuring system is calibrated with the surface standard samples roughness
beforehand, the surface roughness actual value Ra may be obtained in the case of the same material surfaces ground at
the same manufacture conditions.
Photonic crystal fiber is glass or polymer fiber with array of microscopic air holes running along length of the fiber. Waveguide properties of such fiber can be controlled by introducing additional materials into the air holes. Liquid crystals (LC) are very suitable for that purpose because its refractive index can be easily tuned by electric field or temperature. Alignment of LC in photonic holes determines mostly the optical properties of the fiber. In this paper, we have developed the technique of photo-configurable alignment of LC in glass micro-tubes and in photonic crystal fiber. The order parameter of LC has been obtained from FTIR spectroscopy data and has demonstrated good alignment quality. Presented technique can be used as non-contact method of LC alignment in complex photonic crystal structure.
We develop half-wave retarder based of deformed-helical ferroelectric (DHF) liquid crystal cell. Birefringence and thickness of DHF cell is optimized to obtain ninety degrees rotation of the light polarization. An optical scheme of crossed-switch between two inputs and two outputs channels using such DHF cell is discussed. The switching time, less than 10 microseconds at controlling voltage of 20V can be provided, which is temperature independent over the broad temperature range.