| 摘要 |
PURPOSE:To make it possible to perform correct measurement of length all the time even if radiation energy and the like are changed, by receiving the radiation energy and the like from a material to be measured, and adequately correcting the set value in correspondence with a peak value. CONSTITUTION:Radiation energy L corresponding to a length W from a body 1, which is changed by wavelength and temperature, is received by an image sensor 4. A peak value VP of the light is detected by a peak value detecting circuit 5. A set value VT, which is corrected in correspondence with the peak value VP through a setting device 6, is determined as VT=alphaVP. The number of picture elements (a) of the value of the received light, which is higher than the set value, from the image sensor is counted by a counter 9 through a comparator circuit 8. Thus the length W is measured. In this constitution, the set value is corrected in correspondence with the peak value. Therefore, the correct length measurement can be performed all the time, even though radiation energy is changed due to temperature change and the like and the magnitude of signal leakage is changed due to mutual interference among the picture elements of the sensor. When light is received from a light source, which is shielded by the material to be measured, the same procedure can be used. |
