Liquid Chromatography Detectors - Liquid Light Scattering Detectors > The Low Angle Laser Light Scattering Detector > Page 78

                       

       or                                                       

Now (c), (K), and (Rf) are either known or can all be calculated from known data and light scattering measurements; thus, by plotting  against (c) a straight line will be produced with  the intercept being .

The Low Angle Laser Light Scattering Detector

The optical system of the low angle laser light scattering detector produced by LDC Analytical of the Thermo Instruments Corporation is shown diagramatically in figure 51. To conserve space, a folding prism is used that allows the device to be contained to a reasonable size yet accommodate the length of the laser generator. Light from the laser passes through a diverging lens, through a chopper and then through the folding prism. On leaving the prism the beam passes through some measuring attenuators and a calibrating attenuator shutter and then through the cell. An annular mask is situated between the cell and the relay lens and only allows light scattered in the cell at a low angle to pass to the relay lens. Between the annular shutter and the relay lens is a safety attenuator that ensures that none of the potentially damaging laser light can reach the photomultiplier. The scattered light is focused through a field stop onto the forward detector lens. Between the field stop and the forward detector lens is a prism that allows the scattered light to be viewed through a microscope.