A method, system, apparatus, and/or device to determine a condition of a user using a miniaturized collimator. The method, system, apparatus, and/or device may include: a carbon nanotube structure comprising a microtube that includes a set of aligned carbon nanotubes infiltrated by carbon and a through-channel, the carbon nanotube structure having a defined height to through-channel width aspect ratio, where: the defined height to through-channel width aspect ratio is based on a defined collimation to diffraction ratio; the set of aligned carbon nanotubes infiltrated by carbon is configured to absorb a first portion of light that travels through the through-channel at a first angle and impinges a side of a first through-channel portion; and the set of aligned carbon nanotubes infiltrated by the carbon is configured to allow a second portion of the light that enters the through-channel at a second angle to pass through the through-channel.