Finetuning LEDS for a better li How light spectrum makes a di

摘要

In our last article we examined the potential for saving energy by integrating dimmable horticultural LED lighting systems into various feedback-control strategies. This time, we will review background concepts of LED light spectrum and explore how spectral modifications can be leveraged to improve crop production.Quite often we hear questions such as "Are LEDs better than HPS?" and "How do I use LEDs in my operation?". To answer these types of questions, we need to understand the basics about the light that LEDs produce. It is also important to understand that there can be important differences in the spectral output of different LEDs of a given 'colour' (e.g. 'red' or 'blue'). Bare (i.e. uncoated) LEDs are considered monochromatic, meaning each diode produces a single 'colour' of light. More accurately, each LED produces a narrow range of wavelengths,and whose spectral power distribution usually follows a bell-shaped curve. LEDs are often characterized according to their peak wavelength (i.e. the highest point on the curve) and the width of the peak at half of the maximum height (dubbed 'full-width half-maximum' or FWHM). Since the LEDs used by various manufacturers can have different properties these metrics can help the end-user evaluate different systems they are considering.