Nikon IGS fluorescent microscope filter cube. The Nikon number is 78653  and it will fit the Nikon Labophot, Labophot-2, Optiphot, Optiphot-2, Microphot and TMD inverted microscope. It comes in an original plastic filter cube case which is not pictured.

IGS Cube - In addition to the standard fluorescence cubes, manufacturers may offer a cube for immuno-gold staining. This cube, in place of a dichroic mirror, has a standard half-mirror similar to the kind used in metallurgical brightfield reflected light microscopy. In place of an exciter filter, there is positioned a long pass 420 nanometer barrier filter (to block light below 420) and a polarizing filter oriented to pass light vibrating only east-west perpendicularly to the light entering the cube. In place of a barrier filter on the cube, there is another polarizing filter (serving as an analyzer) which allows only light vibrating north-south to the light path to pass to the eye or detector. The analyzer may be placed in a not quite crossed position with respect to the polarizer. The immuno-gold (or silver) stain shows up quite clearly as it adheres to specific targets being studied.