Planar area light source

A system for analyzing a sample, comprising:

• a sample card;
• a planar-area-light source;
• and
• an imager comprising an image sensor and a lens,
• wherein the sample card comprises:
• a first plate and a second plate that sandwich a sample, between the two plates, into a thin layer of a thickness of 200 um or less, and wherein the sample contains or is suspected of containing an analyte;
• wherein the planar-area-light source comprises:
• (i) a light extraction plate having a surface comprising a light scattering structure;
• and
• (ii) a side-emitting optical fiber comprising a light emitting sidewalk;
• wherein the side-emitting optical fiber extends laterally across the light extraction plate, a portion of the light emitting sidewall is positioned within the light extraction plate and is configured to emit light into the light extraction plate;
• wherein the light scattering structure extracts light from inside of the light extraction plate to outside of the light extraction plate;
• wherein the sample card is positioned in parallel with the light extraction plate, such that the light emitted from the light extraction plate uniformly illuminates a surface area of the sample card;
• and
• wherein the imager images the sample.