Water vapor distribution measurement apparatus
A water vapor distribution measurement apparatus comprises: a light source that emits near-infrared light; a near-infrared light measurement device that is located across a measurement space from the light source and that measures the near-infrared light; an optical system that expands and applies the near-infrared light emitted from the light source in the measurement space in which a cross-section of the measurement space perpendicular to a direction connecting the light source to the near-infrared light measurement device has an area; and a distribution deriving means for deriving a water vapor distribution in the cross-section of the measurement space on the basis of a measurement result obtained by the near-infrared light measurement device. Water vapor in a measurement region having a prescribed size can be measured by this water vapor distribution measurement apparatus.
1 . A water vapor distribution measurement apparatus comprising:
a light source configured to emit near-infrared light having a wavelength that can be absorbed by water vapor;
a near-infrared light measurement device which is located by sandwiching a two-dimensional measurement space with respect to the light source, and configured to measure a two-dimensionally light absorbance of the near-infrared light, that has passed through the measurement space, at a two-dimensional measurement surface;
an optical system configured to enlarge the near-infrared light emitted from the light source and irradiate the measurement surface; and
a distribution deriving means configured to derive a distribution of water vapor in the two-dimensional measurement space based on the two-dimensionally light absorbance of the near-infrared light measured by the near-infrared light measurement device.
2 . The water vapor distribution measurement apparatus according to claim 1 , comprising the light source configured to emit near-infrared light having a wavelength of 1800 nm to 1900 nm.
3 . The water vapor distribution measurement apparatus according to claim 2 , comprising the light source configured to alternately emit near-infrared light having a center wavelength of 1866 nm, where the absorbance of water vapor is the maximum in the range of 1800 nm to 1900 nm, and near-infrared light having a center wavelength of 1800 nm, where the absorbance of water vapor is much smaller than at 1866 nm.
4 . The water vapor distribution measurement apparatus according to claim 1 , comprising: the light source which includes a laser light source configured to emit near-infrared laser light; and the optical system which includes:
an integrating sphere configured to multiply reflect the near-infrared laser light from the light source inside to emit incoherent near-infrared light;
a concave lens configured to refract the near-infrared light from the integrating sphere according to the two-dimensional measurement space; and
a convex lens configured to refract the near-infrared light that has passed through the concave lens to irradiate the two-dimensional measurement space with the light.
5 . The water vapor distribution measurement apparatus according to claim 1 ,
comprising: an isolation member located within the two-dimensional measurement space and having an internal space isolated from outside air; and
the distribution deriving means configured to derive the distribution of the water vapor in the two-dimensional measurement space outside except the isolation member based on a measurement results of the water vapor in the internal space.
6 . The water vapor distribution measurement apparatus according to claim 5 , wherein a noise in the measurement results of water vapor in the two-dimensional measurement space except the isolation member is removed by using the measurement results of water vapor in the internal space.