A backplane has an array of output terminals arranged on an output surface of the backplane, and an array of solid state optical switches, each optical switch corresponding to one of the output terminals, wherein the solid state optical switches are responsive to light of a control wavelength and are transparent to light of a sensing wavelength, wherein the backplane is of a material transparent to light of a sensing wavelength different from the control wavelength. An optical system includes a backplane having an array of optocouplers, a projector to generate light of a control wavelength to which the optocouplers are responsive, optics to direct the control light onto the array of optocouplers on a backplane, an imaging system responsive to light of a sensing wavelength, wherein the backplane is at least partially transparent to the sensing wavelength.