156
D. K. Pandey et al.
Fig. 5 Diffraction of
incident light from the
grating elements
to obtain the desired spectrum by using the spectral dispersion at a selected wavelength, then the angles and the focal length of the focusing element. These are kept
images as tight as possible on the surface of the flat detector. The Raman spectrum
becomes meaningful when the given wavelength values are converted to the Raman
shifts using the following relation,
v Raman = v Laser ± v V ibration = v
(16)
Here v is derived from λ(wavelength) by using
v(cm
−1
) = 1/λ nm
(17)
By using the above equations, the spectrum can be obtained in the wavenumber
shifts consisting of widths of lines (full width at half maxima- FWHM) between
1 and 10 cm
−1 . Therefore, to enhance the pixels or resolution of the spectrum the
selection of grating would be straightforward and significant. Moreover, the dispersion obtained in the Raman scattering is also depending on the groove density, and
focal length [18]. Further, the reflectivity is a complex function of the groove shape,
density, polarizability of the light on grating and spacing. It is also dependent on the
groove profile along with the angle of grating tilt, and the metallic coating applied
to the surfaces [14, 18, 19].
D. K. Pandey et al.
Fig. 5 Diffraction of
incident light from the
grating elements
to obtain the desired spectrum by using the spectral dispersion at a selected wavelength, then the angles and the focal length of the focusing element. These are kept
images as tight as possible on the surface of the flat detector. The Raman spectrum
becomes meaningful when the given wavelength values are converted to the Raman
shifts using the following relation,
v Raman = v Laser ± v V ibration = v
(16)
Here v is derived from λ(wavelength) by using
v(cm
−1
) = 1/λ nm
(17)
By using the above equations, the spectrum can be obtained in the wavenumber
shifts consisting of widths of lines (full width at half maxima- FWHM) between
1 and 10 cm
−1 . Therefore, to enhance the pixels or resolution of the spectrum the
selection of grating would be straightforward and significant. Moreover, the dispersion obtained in the Raman scattering is also depending on the groove density, and
focal length [18]. Further, the reflectivity is a complex function of the groove shape,
density, polarizability of the light on grating and spacing. It is also dependent on the
groove profile along with the angle of grating tilt, and the metallic coating applied
to the surfaces [14, 18, 19].