Fig. 3.

Diagram of the laser illumination system. Output from the laser head is expanded by two Keplerian beam expanders before illuminating the zebrafish heart. The first beam expander is formed by f₁ and f₂ and is separated by a distance of f₁+f₂. For f₁ = 30 mm and f₂ = 150 mm, the separation distance is 180 mm. The second beam expander is formed by f₃ (30 mm) and f₄ (75 mm) with a separation distance of 105 mm. A dichroic mirror is positioned between f₃ and f₄ to reflect the light toward the imaging chamber.