| 摘要 |
PURPOSE:To prevent the generation of dew condensation on an optical window of a measuring cell by controlling a heater near the optical window of the cell on the basis of a difference of detected temperatures between the optical window and atmosphere. CONSTITUTION:Laser beams 3 made incident from an incident window 4 of the measuring cell 20 are dispersed by fine grains in a fluid solution and dispersed light 14 through a light receiving window and transmitted light through a projecting window 11 are received and detected to measure the characteristics of fine grains in the solution. Since a reflection preventing window 21 is formed on the cell 20 and an optical window temperature detecting thermistor 32 is also fitted in the vicinity of the window 21, heaters 4d, 5d, 11d, 21d on respective windows are controlled in accordance with the difference between detecting temperatures based upon the thermistor 32 and an atmospheric temperature detecting thermistor 31. Consequently, the optical window on the measuring cell can be prevented from the generation of dew condensation based upon the temperature difference and excellent measurement can be attained. |
