Cultivation Container Waveguide for High Contrast Cell Observation

The cultivation container is divided into distinct functional regions: a waveguide substrate for light guidance, a surrounding wall to contain cells, and a shielding part to block light leakage. This segmentation allows each component to address specific aspects of the contradiction - the waveguide confines light to prevent leakage while the shielding part blocks any stray light that might interfere with observation.

The waveguide substrate acts as an intermediary between the light source and the cells. It receives measurement light from the light source, guides it through total internal reflection, and directs it to illuminate only the cells in the cultivation space. This intermediary function prevents light from directly leaking into the observation path while still achieving the desired illumination for high-contrast dark field observation.

The waveguide substrate is designed with specific optical properties (refractive index) that enable total internal reflection. This local quality of the waveguide material allows it to confine light laterally while permitting oblique incidence for dark field observation. The light spreads only within the waveguide's optical path rather than throughout the entire cultivation container, maintaining contrast enhancement without excessive light spread.

The waveguide substrate utilizes total internal reflection to guide light in a controlled manner through the thickness dimension of the substrate. By incidenting light obliquely on the waveguide surface, the light is reflected back and forth within the waveguide thickness, confining it to a specific region. This dimensional control prevents light from spreading horizontally across the entire cultivation container while still achieving the oblique illumination needed for dark field contrast.