Nodal Slide Assembly With Optical Bench PSAW It consists of a 1½ meter long stainless steel double rod optical bench with the following accessories. (a) Lamp house : an electric bulb workable on 220V AC is encased in a metal case. (b) Metal Screen White with cross slit : the slit has one white surface and other black. (c) Plate true titable mounted mirror. (d) Lens assembly consisting of combination of single & double lens holder on a mount rotating on a vertical axis.The assembly is adjustable in height and can be moved by rack & pinion.