An optical device comprising: an eyepiece; an objective; and an image intensifier module; wherein the objective is configured to receive first light from an environment and to transmit the first light to the image intensifier module; the image intensifier module comprises an image intensifier configured to amplify and output the received first light, and an overlay display system; the overlay display system comprising: - a semiconductor chip configured to generate second light based on pixel values of a display image; wherein the semiconductor chip comprises a bottom surface configured to receive the output amplified first light and a top surface configured to output the second light and the amplified first light, and an array of pixels comprising light emitters arranged with transparent regions between them so such that light passing through the bottom surface can pass to the top surface, and wherein the light emitters are configured to generate the second light with an intensity emitted based on respective pixel values of a display image; a frame buffer configured to the store pixel values in a computer readable memory, and configured to communicate, at a first frame rate, the pixel values to the light emitters; and a processor configured to update, at a second frame rate, pixel values stored in the frame buffer; wherein the eyepiece comprises optics adapted to focus the light from the semiconductor chip into the eye of a user. an eyepiece; an objective; and an image intensifier module; wherein the objective is configured to receive first light from an environment and to transmit the first light to the image intensifier module; the image intensifier module comprises an image intensifier configured to amplify and output the received first light, and an overlay display system; the overlay display system comprising: - a semiconductor chip configured to generate second light based on pixel values of a display image; wherein the semiconductor chip comprises a bottom surface configured to receive the output amplified first light and a top surface configured to output the second light and the amplified first light, and an array of pixels comprising light emitters arranged with transparent regions between them so such that light passing through the bottom surface can pass to the top surface, and wherein the light emitters are configured to generate the second light with an intensity emitted based on respective pixel values of a display image; a frame buffer configured to the store pixel values in a computer readable memory, and configured to communicate, at a first frame rate, the pixel values to the light emitters; and a processor configured to update, at a second frame rate, pixel values stored in the frame buffer; wherein the eyepiece comprises optics adapted to focus the light from the semiconductor chip into the eye of a user. - a semiconductor chip configured to generate second light based on pixel values of a display image; wherein the semiconductor chip comprises a bottom surface configured to receive the output amplified first light and a top surface configured to output the second light and the amplified first light, and an array of pixels comprising light emitters arranged with transparent regions between them so such that light passing through the bottom surface can pass to the top surface, and wherein the light emitters are configured to generate the second light with an intensity emitted based on respective pixel values of a display image; a frame buffer configured to the store pixel values in a computer readable memory, and configured to communicate, at a first frame rate, the pixel values to the light emitters; and a processor configured to update, at a second frame rate, pixel values stored in the frame buffer; wherein the eyepiece comprises optics adapted to focus the light from the semiconductor chip into the eye of a user. a frame buffer configured to the store pixel values in a computer readable memory, and configured to communicate, at a first frame rate, the pixel values to the light emitters; and a processor configured to update, at a second frame rate, pixel values stored in the frame buffer; wherein the eyepiece comprises optics adapted to focus the light from the semiconductor chip into the eye of a user.