Systems, methods, devices, and computer program products are provided for producing observable virtual images. Aspects may include at least one illumination source emitting light on a display and a transparent combining optic including a holographic optical element (HOE). According to various examples, light emitted from the at least one illumination source illuminates the transparent combining optic, and the transparent combining optic diffracts the light to generate an observable virtual image. The observable virtual image may be positioned to overlay a scene viewable through the transparent combining optic. Such aspects may be incorporated on a variety of technologies, such as head-mounted display systems, smart glasses, and/or AR devices.