Transducers optical, laser

Sakamoto Y, Takai K, Takashima I, Imada M (1996) Electrical resistance measurements as a function of composition of palladium-hydrogen(deuterium) systems by a gas phase method. J Phys Condens Matter 8 3399-3411 Schroeder K, Ecke W, WUlsch R (2009) Optical fibre Bragg grating hydrogen sensor based on evanescent-field interaction with palladium thin-film transducer. Opt Lasers Eng 47(10) 1018-1022 Sharma AK, Gupta BD (2007) On the performance of different bimetaUic combinations in surface plasmon resonance based fiber optic sensors. J Appl Phys 101(9) 093111... 

Laser Surface acoustic wave Semiconductor Target transducers Optical fiber Radiation Radar Surface acoustic wave Electrophoresis Electrochemical Paramagnetic Chemi/bioluminescence Tunable diode laser absorption... 

Optical devices have also been used as transducers. Laser fiber-optics allows high intensity light to travel a long distance using fibrous size carrier. The stable and intense light beam not only provides calibration stability but also makes all the detecting techniques faster and more sensitive. In addition to the UV-VIS absorbance and fluorescence intensity, measurements of multiple reflections, surface plasmon resonance, and total internal reflection fluorescence had recently been used (12, 13, 14). 

In addition to the work presented here, several alternative viral-vectored approaches have been reported recently. An adeno-associated viral vector (AAV) encoding the soluble VEGF receptor 1, sFlt-1, shows promise for long-term inhibition of two types of ocular neovascularization (Lai et al., 2002). This vector, when injected into the anterior chamber, resulted in expression in both the corneal endothelium and iris pigment epithelium and reduced corneal NV by 36%. Subretinal injection of the same vector reduced choroidal NV subsequent to laser lesions around the optic nerve. These results suggest that a secretable factor expressed in one or more transduced cell populations can be elfective in the control of ocular NV occurring in a disparate cell population. 

The operation of proximity sensors can be based on a wide range of principles, including capacitance, induction, Hall and magnetic effects variable reluctance, linear variable differential transformer (LVDT), variable resistor mechanical and electromechanical limit switches optical, photoelectric, or fiber-optic sensors laser-based distance, dimension, or thickness sensors air gap sensors ultrasonic and displacement transducers. Their detection ranges vary from micrometers to meters, and their applications include the measurement of position, displacement, proximity, or operational limits in controlling moving components of valves and dampers. Either linear or angular position can be measured ... 

Fig. 5. Experimental setup for locking the offset frequency u>o- The femtosecond laser is located inside the shaded box. Solid lines represent optical paths, and dashed lines show electrical paths. The high-reflector mirror is mounted on a transducer to provide both tilt and translation...

For a typical measurement, the phosphor transducer is mounted on the test surface, and a pulse laser is used to excite the transducer. Then, the time evolution of the phosphors fluorescence spectrum is captured by an optic filter and an optoelectronic device. The fluorescence thermometer should be carefully calibrated before application in temperature measurements. 

FIGURE 18-9 Raman spectrometer with fiber-optic probe. In (a) a microscope objective focuses the laser radiation onto excitation fibers that transport the beam to the sample. The Raman scattering is collected by emission fibers and carried to the entrance slit of a monochromator or to the entrance of an interferometer. A radiation transducer, such as a photomultiplier tube, converts the scattered light Intensity to a proportional current or pulse rate (b) end view of the probe (c) end view of collection libers at entrance slit of monochromator. The colored circles represent the input fiber and the uncoiored circles the collection fibers. (Adapted from R. L. McCreery. 

The ideal collection optic would collect fluorescence from a Ansr solid angle around the detection zone with 100% efficiency, while being completely inefficient at collecting scattered laser light. Obviously, there exists no such optic, but there are various approaches reported in the literature taken to emulate this ideal. In most cases, either a high numerical aperture microscope objective or a fiber-optic system is used to collect the fluorescence and transmit it to the signal transducer. 

---