One of the issues making underground real estate unpopular with engineers is the lack of the ability to grow plants. Artificial lighting has low efficiency – recently, Würth introduced a set of LEDs targeted to the needs of plants.
High school biology teaches that photosynthesis requires the presence of light. In practice, not every light will do – instead, particular plants have particular pigments, which do not respond to some spectral elements. Würth‘s (smart) reasoning is that farting out unneeded spectral components is a waste of energy and a sure-fire way to cause thermal problems. Thus, their LEDs emit light only in very tight spectral dimensions.
…from a plant‘s point of view, some lights shine brighter than others
Persons familiar with technical optics recognize that most of the efficient color ranges would be perceived as red and blue – three parts cover the important parts of the spectrum:
If price is not an issue or optimum efficiency is required, the company provides additional light sources with infrared and various forms of normal day- and night light. One especially interesting one is the 158353040, whose light intensity is described as moonlight. Interior designers can use these to spruce up night-light installations.
Those interested in finding out more about which LEDs to choose for the plant in question are served by an application note written by a famous biologist. The PDF file, available here, provides an overview of the various questions at hand.
One interesting aspect of the part is a very uncommon land design shown in figure two. The part has two electric and one thermal pad which must be connected to some kind of thermal heatsink.
Finally, be advised to wait when chasing these LEDs. Würth recently performed a significant upgrade of the materials used, leading to higher light output per part.
The land layout of Würth‘s LEDs is quite odd…