The GardeNIRS is an automated home garden system that employs a low-cost Near Infrared Spectroscopy sensing unit.
The goal is to create a system that gathers broad information about plant health, a control plan for adjusting soil
conditions, a user interface for displaying information to the gardener, and a power generation system for sustainability.
The optical subsystem creates spectrographs on a microcontroller by scanning a pair of photodetectors in the path of a
beam reflected off the soil. The broadband tungsten source is separated into wavelengths by unit distance using a
reflective diffraction grating. In order to achieve this simplicity of design, optical components had to be modeled
mathematically and carefully selected for our unit’s geometry. The diffraction angles of incident light from a range of
directions were calculated in MATLAB, the proper distances for focus on the sensors were calculated in ZEMAX. A 3D
modeling software called Fusion 360 was used to create optical mounts and carefully position the components. The result
is a short-range spectrometer that costs less than a third of units on the low-end market.