Lambda 20/Lambda 40 Installation and Maintenance Guide - VTP UP

Lambda 20, Lambda 40 UV/Vis SpectrometersThe beam then passes through a convex lens onto the photodiode detector.Mirror M5 focuses the radiation beam in the reference cell.The beam then passes through a convex lens onto the photodiode detector.Optical System Lambda 40The optical system is depicted schematically in Figure 18.The Lambda 40 UV/Vis Spectrometer features an all-reflecting optical system. Theoptical components are coated with silica for durability. A holographic grating isused in the monochromator.The monochromator is a holographic concave grating with 1053 lines/mm in thecenter.Two radiation sources, a deuterium lamp and a halogen lamp, cover the workingwavelength range of the spectrometer.For operation in the visible (Vis) range, mirror M1 reflects the radiation from thehalogen lamp onto source mirror M2. At the same time M1 blocks the radiationfrom the deuterium lamp. For operation in the ultraviolet (UV) range, mirror M1 israised to permit radiation from the deuterium lamp to strike source mirror M2.Source change is automatic during monochromator slewing.Radiation from the source lamp is reflected from source mirror M2 through anoptical filter on the filter wheel assembly.A stepping motor drives the filter wheel to be in sychronization with themonochromator.Depending on the wavelength being produced, the appropriate optical filter islocated in the beam path to prefilter the radiation before it enters themonochromator. Filter change is automatic during monochromator slewing.From the optical filter the radiation passes through the entrance slit (Selectable Slit1) of the monochromator.78