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A system and method for fabricating optical ramp filters utilizes an ion beam sputter etching system and a shaped aperture mask to produce optical ramp filters with precise control over the transmission and reflectance properties of the filter. The ion beam is passed through a shaped aperture whose width varies as a function of its length. The resultant shaped ion beam is used to etch a uniform reflective layer that was previously deposited on a transparent substrate. The substrate and the reflective layer are translated relative to the shaped aperture so that the shaped ion beam "travels" across the reflective layer. Different parts of the reflective layer are exposed to the ion beam for different amounts of time as a result of the varying width of the shaped ion beam. The result is a reflective layer with a nonuniform depth profile (a ramp filter). The method allows control of the layer thickness with a precision of less than 0.5 nm. This precision exceeds that achieved with prior fabrication methods that control the thickness of the layer during the deposition (or growth) stage.