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PAT. NO. TITLE ISSUE DATE US6750995B2 Enhanced volume phase grating with high dispersion, high diffraction efficiency and low polarization sensitivity June 15, 2004 US7321466B2 High dispersion diffraction grating including multiple holographic optical elements January 22, 2008 US8537466B2 High dispersion diffraction grating including multiple holographic optical elements September 17, 2013 US8077929B2 […]
A Dickson grating works well over a narrow bandwidth of 20 to 60 nm but falls off quickly with wider bandwidths. It caused a lot of excitement for applications in Dense Wavelength Division Multiplexing (DWDM), Raman spectroscopy and Optical Coherence Tomography (OCT). DWDM applications benefit from the Dickson design since […]
When a grating design exceed a 36° for the angle of incidence (AOI) and angle of diffraction (AOD), P polarized light drops significantly with a standard volume phase grating. (Fig 1) Fig 1 Standard volume phase grating at 1800 l/mm Lee Dickson’s work with the holographic barcode scanner helped him […]
Volume Phase Gratings have many advantages over SR or surface relief gratings. However they cannot break the laws of physics. Gratings with low dispersion and a diffraction angle under 30° have low polarization dependency. Gratings made for high dispersion with an angle of incidence greater than 30° will start exhibiting […]
A typical surface relief grating is not as thick as a volume phase grating. Most are coated with a reflective surface and used as a reflection grating. The grating structure is usually be “blazed” to work at the desired wavelength and geometry. Volume phase grating can be made thicker than […]
