LD-LDVの光源光学系の改善

概要

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Abstract In an internal combustion engine, promotion of combustion is one of the factors to achieve low fuel consumption, low exhaust pollution and high thermal efficiency. Promotion of combustion is related to in-cylinder gas flow. There is laser doppler velocimetry (LDV) in one of equipment to measure in-cylinder gas flow. We changed light source from gas laser of large size to laser diode (LD) of small size for miniaturization to improve in flexibility. LD light has an extension angle different in vertical and horizontal direction, therefore beam section becomes elliptic section. There is possibility that beam power cannot be fully used by this cause. Then, in this research, we studied about the way of collimation to use beam power efficiently. As a result, we found the way of collimation to reduce beam diameter and increase beam strength. But, this way caused decline of S/N due to increase of noise. Then, when we measured with frequency shifter, we were not possible to measure in-cylinder gas flow, and more examination should be required.
宮崎大学の論文