Spectrometric device and spectrometric method

A spectroscopic measurement apparatus comprising:

• an optical system configured to disperse measurement target light to form a spectral image;
• a photodetector including a light receiving surface on which a plurality of pixels are arranged respectively on a plurality of rows with the spectral image having a wavelength axis in a pixel arrangement direction of each of the plurality of rows being formed on the light receiving surface, and configured to receive the spectral image for a first exposure time by a plurality of pixels arranged on a plurality of rows in a first region on the light receiving surface to output first spectrum data of the measurement target light, and receive the spectral image for a second exposure time by a plurality of pixels arranged on a plurality of rows in a second region on the light receiving surface to output second spectrum data of the measurement target light;
• and
• an analyzer configured to obtain a spectrum of the measurement target light based on the first spectrum data and the second spectrum data, wherein
• the second exposure time is longer than the first exposure time,
• in the first region, charges generated in each pixel are transferred to and output from one side of the light receiving surface in a vertical transfer direction,
• in the second region, charges generated in each pixel are transferred to and output from the other side of the light receiving surface opposite to the one side in the vertical transfer direction, and
• the analyzer is configured to
• divide an entire wavelength band of the spectrum into a saturation wavelength band including a wavelength band in which a value is at a saturation level or more in the second spectrum data and a non-saturation wavelength band other than the saturation wavelength band, the non-saturation wavelength band being adjacent to the saturation wavelength band, and
• obtain the spectrum of the measurement target light in the entire wavelength band by combining first partial spectrum data of the saturation wavelength band in the first spectrum data and second partial spectrum data of the non-saturation wavelength band in the second spectrum data, and wherein
• the optical system is configured to form the spectral image such that the spectral image on the light receiving surface has a symmetrical shape with a center line as a symmetry axis, and
• the light receiving surface is divided into the first region and the second region with the symmetry axis of the spectral image to be formed as a boundary.