Optical assemblies for use in virtual and augmented reality environments are described. The optical assemblies may include lenses, filter stacks, cameras, and image projecting devices. For example, the optical assemblies may include at least one lens, a first filter stack between the at least one lens and an image projecting device, a second filter stack between the first filter stack and the image projecting device, and a camera configured to capture images of an infrared reflection of light through the at least one lens.