Figure 1. A laser-illuminated plant growth chamber prototype and its beneficial attributes for horticultural applications.

(a) Beneficial attributes of single-wavelength laser light for horticulture²⁷,⁶⁴. (b) A laser-illuminated plant growth chamber prototype used in this study. Inset: (i) Light distribution (magenta in color) of the laser illuminated growth area upon passing through the engineered diffuser. (ii) Position of the red (671 nm) and blue (473 nm) DPSS lasers and the optics inside the protective black metal case. (c) Schematic illustration of the prototype and the potential applications of laser as primary and supplementary lighting for horticulture and light-related research. The laser modules and optics are installed external of a custom-made growth chamber (Percival Scientific, Perry, IA) and are enclosed in a protective black metal case. The laser illumination system consists of two diode-pumped solid-state (DPSS) lasers (maximum power output: >500 mW; Class IV; Laserglow technologies, Toronto, Canada) that generate a 9:1 ratio of red (671 nm) and blue (473 nm) laser beams that are combined at a 1.27 cm short-pass dichroic mirror (with a cut-off wavelength at 589 nm) and guided a 1-inch diameter multiple-ground glass engineered diffuser with a 50-degree divergence angle that is custom-fitted at an opening on the roof of the chamber providing a non-Gaussian magenta-colored square light-pattern distribution illuminating an area of 227 cm² that is fixed at 20 cm vertically below the diffuser.