Liquid filters are useful for applications where the infrared is not required, and its heating effect is a problem. With our high powered sources (500 to 1600 W), they are almost a necessity if you are using other optical components. (Another alternative is Beam Turning Assemblies)
Our liquid filters use a fused silica window to transmit down to 250 nm; the NIR is absorbed by the liquid. See Fig. 1 for a transmittance curve of the 6123NS filled with distilled water.
The filters consist of a cell that holds the liquid and two fused silica windows. The cell has an external chamber for cooling water circulation and a pressure relief valve. External cooling is needed to remove the energy absorbed when filtering continuous high power (>100 W) sources. You can use tap water or water from a recirculating cooler.
The aluminum models take distilled water only. The steel models can take water, or copper or nickel sulfate solutions. Copper and nickel sulfate solutions prevent the growth of organics. Normal laboratory precautions should be taken when working with these solutions.
Fig. 1 Transmittance of 6123NS Liquid Filter with distilled water.
