242
T. Okura
Fig. 10.10 The effect of the spectral slope on the wavelength accuracy, the reflectance of a leaf
and its second derivative (a), and magnified graph around 1728 nm (b)
A laser is incorporated to calibrate wavelength with high accuracy in a Fourier-type
spectrometer. A high-resolution rotary encoder is used to detect the grating rotation
angle with high accuracy in a wavelength scanning-type grating spectrometer.
10.2 Grating Spectrometer
When considering the in-plane optics of a spectrometer, the off-plane angle δ is set
to zero with the first order of diffraction, as shown in Fig. 10.11.
The relationship between the incident angle α, diffracted angle β, and wavelength
λ can be expressed by Eq. 10.3 using the groove density N of the grating (see 5.2)
[6].
λ =
10
6
N
· (sinα + sinβ)
(10.3)
λ Wavelength (nm)
N Groove density (mm
−1 )
Fig. 10.11 The principle
behind diffraction grating
T. Okura
Fig. 10.10 The effect of the spectral slope on the wavelength accuracy, the reflectance of a leaf
and its second derivative (a), and magnified graph around 1728 nm (b)
A laser is incorporated to calibrate wavelength with high accuracy in a Fourier-type
spectrometer. A high-resolution rotary encoder is used to detect the grating rotation
angle with high accuracy in a wavelength scanning-type grating spectrometer.
10.2 Grating Spectrometer
When considering the in-plane optics of a spectrometer, the off-plane angle δ is set
to zero with the first order of diffraction, as shown in Fig. 10.11.
The relationship between the incident angle α, diffracted angle β, and wavelength
λ can be expressed by Eq. 10.3 using the groove density N of the grating (see 5.2)
[6].
λ =
10
6
N
· (sinα + sinβ)
(10.3)
λ Wavelength (nm)
N Groove density (mm
−1 )
Fig. 10.11 The principle
behind diffraction grating