Investigation On The Diffraction Properties Of The Varied Line Space Plane Grating

The varied line space(VLS)plane grating not only has the dispersion properties but also has the focusing properties,so it can be widely used in many fields.However,many diffraction properties of the VLS plane transmission grating have not been revealed,which limits the applications of the VLS plane transmission grating.Therefore,studying the diffraction properties of the VLS plane transmission grating further is not only useful to explore the new diffraction phenomena and laws,but also important to provide some guides for many applications.The diffraction properties of the one-dimensional VLS plane transmission grating and two-dimensional curved VLS plane transmission grating were investigated deeply in this paper.First,a diffraction imaging theory based on Fermat's principle for VLS plane transmission grating was established and focusing imaging formulae and dispersion relationships were obtained.Second,the dispersion and focusing properties of the one-dimensional VLS plane transmission grating using plane waves and spherical waves as the incident light separately were experimentally studied.The obtained experiment results coincide with the theoretical analysis.Thirdly,a set of two-dimensional curved VLS plane transmission grating were designed,and these gratings were fabricated by the holographic method.The focusing properties of the two-dimensional curved VLS plane transmission grating using plane waves and spherical waves as the incident light separately were experimentally and theoretically studied.By experimentally and theoretically studying,the dependences of the diffraction properties of the one-dimensional VLS plane transmission grating and two-dimensional curved VLS plane transmission grating on the spatial frequency distribution of VLS gratings,the wavelength of the incident light,the incident angle and the incident light type were obtained.Based on the diffraction properties of VLS gratings,a two-grating spectrometer consisting of a one-dimensional VLS plane transmission grating and periodic grating and a two-grating monochromator consisting of a one-dimensional VLS plane transmission grating and periodic grating were designed,and theories illustrating the principles of these instruments were established.Using the designed two-grating spectrometer,two spectrum lines of the waves with the wavelengths of 576.96nm and 579.07nm emitted by a mercury lamp were clearly observed.Furthermore,using the designed two-grating monochromator,the light wave with the wavelength of 579.07nm was separated from emitting light waves of a mercury lamp.