The excited state upconversion of Pr(0.5):ZBLAN under two-color excitation;

Meanwhile,the exact displacement of the CCD camera can be measured by a double-frequency laser interferometer,the needed coordinates of the feature points in the object plane and in the correlative i.

There are two reasons for negatives in measuring double-frequency induced polarization,one is electromagnetic coupling effect,the other is geo-boby existing in an impersonal way.

Aim To investigate the coherent two frequency laser after a single axial mode is split by the way of twisted mode cavity with fine detuning in LD pumped solid state laser.

When dual-frequency laser is used as light source, synthetic wavelength is required as small as possible in the absolute-distance interferometry measurement in order to improve measurement accuracy, namely, it requires the frequency-difference as large as possible.

The experimental setup of an optical feedback dual-frequency laser is developed by using the phase delay between the optical feedback fringes of the two orthogonally polarized lights to realize displacement division and direction discrimination.

A nanometer-resolution displacement measurement system based on weak feedback effect of birefringent dual-frequency laser has been presented and demonstrated.