Transmitting Light with Lateral Variation

Apparatus comprising:

• a stimulus-wavelength converter that provides light within a photon energy range, the converter providing light in first and second sub-bands of the photon energy range in response to first and second values of a stimulus, respectively;
• a transmission structure with entry and exit surfaces, the exit surface including first and second positions;
• the transmission structure being a layered structure;
• and
• a propagation component that propagates light from the converter to the transmission structure's entry surface;
• the transmission structure providing photons at the first and second positions of the exit surface in response to light received at its entry surface;
• the stimulus wavelength converter, propagation component, and transmission structure being configured so that, due to transmission of light with lateral variation, relative quantities of photons provided at the first and second positions change over time in response to change over time between the first and second sub-bands and to output a signal indicating the change over time.

A detection system, comprising:

• an optical sensor that, when illuminated with a broad band of optical wavelengths, outputs approximately the broad band of optical wavelengths with a dark sub-band;
• and
• a detector that includes one or more transmissive layers;
• the optical sensor and the detector being configured so that the detector receives light output by the optical sensor and, due to transmission of light with lateral variation, transmits light in each of a set of wavelengths in the broad band at a respective position of the layers, the detector configured to compare the light transmitted in each set of wavelengths to determine wavelength changes of the dark sub-band in the output from the optical sensor.