A head-mounted display integral imaging, InI, system, comprising: a microscopic InI unit, micro-InI, configured to create light fields of a selected 3D scene at a selected position along an optical axis of the system; a relay unit having a vari-focal element, VFE, disposed therein, the relay unit disposed on the optical axis at a location so the selected position is an optical conjugate of the relay unit, the relay unit configured to receive the light fields created by the microscopic InI unit; and a freeform waveguide prism for receiving light from the relay unit to provide an image of the 3D scene at an exit pupil of the system for viewing by a user of the head-mounted display system, the freeform waveguide prism comprising: a first freeform optical surface disposed to receive light from the lightfield and refract the received light into the body of the prism; a second freeform optical surface disposed to receive the refracted light from the first freeform optical surface and reflect the light into the body of the prism to provide an intermediate image of the lightfield at a selected location within the body of the prism; a third freeform optical surface disposed to receive the light from the intermediate image and total internally reflect the light into the body of the prism; and a fourth freeform optical surface disposed to receive the reflected light from the third freeform optical surface and reflect the light back to the third freeform surface at an angle that allows the light to exit the prism, the first through fourth freeform optical surfaces cooperating so that the light exiting the prism through the third freeform surface produces an image of the light field at selected location external to the prism, wherein the VFE is configured to tune the location of the intermediate image within the body of the prism. a microscopic InI unit, micro-InI, configured to create light fields of a selected 3D scene at a selected position along an optical axis of the system; a relay unit having a vari-focal element, VFE, disposed therein, the relay unit disposed on the optical axis at a location so the selected position is an optical conjugate of the relay unit, the relay unit configured to receive the light fields created by the microscopic InI unit; and a freeform waveguide prism for receiving light from the relay unit to provide an image of the 3D scene at an exit pupil of the system for viewing by a user of the head-mounted display system, the freeform waveguide prism comprising: a first freeform optical surface disposed to receive light from the lightfield and refract the received light into the body of the prism; a second freeform optical surface disposed to receive the refracted light from the first freeform optical surface and reflect the light into the body of the prism to provide an intermediate image of the lightfield at a selected location within the body of the prism; a third freeform optical surface disposed to receive the light from the intermediate image and total internally reflect the light into the body of the prism; and a fourth freeform optical surface disposed to receive the reflected light from the third freeform optical surface and reflect the light back to the third freeform surface at an angle that allows the light to exit the prism, the first through fourth freeform optical surfaces cooperating so that the light exiting the prism through the third freeform surface produces an image of the light field at selected location external to the prism, a first freeform optical surface disposed to receive light from the lightfield and refract the received light into the body of the prism; a second freeform optical surface disposed to receive the refracted light from the first freeform optical surface and reflect the light into the body of the prism to provide an intermediate image of the lightfield at a selected location within the body of the prism; a third freeform optical surface disposed to receive the light from the intermediate image and total internally reflect the light into the body of the prism; and a fourth freeform optical surface disposed to receive the reflected light from the third freeform optical surface and reflect the light back to the third freeform surface at an angle that allows the light to exit the prism, the first through fourth freeform optical surfaces cooperating so that the light exiting the prism through the third freeform surface produces an image of the light field at selected location external to the prism, wherein the VFE is configured to tune the location of the intermediate image within the body of the prism.