摘要 |
In order to achieve highly dispersive spectrometry in wide wavelength with the use of a single grism, but not a plurality of grisms, the grism is composed of a prism the vertex angle of which can be varied and a volume phase holographic (VPH) grating. More specifically, the grism comprises a prism the vertex angle of which can be varied; and a VPH grating being a diffraction grating and disposed substantially orthogonal with respect to a side including the vertex angle of the prism; the VPH grating being rotated around an axis being substantially orthogonal to the side of the prism, whereby a slope angle defined by the VPH grating and a predetermined plane is varied.
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