| 摘要 |
PROBLEM TO BE SOLVED: To reduce the size of a device, and suppress fluctuations in measurement value among devices.SOLUTION: A spectrophotometer 1 comprises: a first lens 7 for making light beams from a light source 2 into substantially parallel light beams; a mask 14 having a first opening 14a for guiding the light beams from the light source 2 to a measurement cell 10 and a second opening 14b for guiding it to a reference cell 11; a shutter 9 for alternately shutting the two opening 14a, 14b; a second lens 8 for converging the light beams having passed through the measurement cell 10 and the reference cell 11; a slit 4 arranged at a focal point of the second lens 8; and a toroidal concave diffraction grating 12 on which each of the light beams having passed through the slit 4 is made incident. Each of the light beams having passed through the measurement cell 10 and the reference cell 11 is made incident on a different region of the toroidal concave diffraction grating 12 among regions arranged in a direction intersecting the blaze direction thereof, and the toroidal concave diffraction grating 12 diffracts the incident light beams and converges them on a substantially same region of a photodetector 13 arranged at the focal point of the toroidal concave diffraction grating 12. |
