Abstract: An incriment optical signal from a potential enemy threat is captured by an array of apertures which are connected to a number of broadband filters. The broadband filters have overlapping band pass regions to cover the wavelength spectrum of potential threats, but not with the spectral resolution of a larger number of narrowband filters. To further increase resolution without adding additional filters, each broadband filter is connected to an optical delay line which converts wavelength into a time delay. To enable measurement of the time delay, additional optical lines with no relative delay are connected directly from the apertures. The time difference between when a signal arrives over optical delay lines from the filters and when a signal arrives over optical lines directly from the array of apertures is then reconverted to wavelength to a high degree of resolution.