In This Issue Plants, Light, and LEDs Part 6 Light Mismeasurement Part 1 Featured Distributor Henckel Gruppen ApS Roedby, Denmark +45 7022 7333 www.henckel.biz/ Featured Product: The SolarOasis Aqua-Bar ABP5 Ideal for Saltwater Tanks, and Freshwater tanks Over 20" deep. Receive 10% off of your purchase of the ABP5 model in the month of August by simply mentioning that you are a reader of the LED Gardener. Order now. 1-866-414-7244 Care to Comment? The LED Gardener appreciates all the input we receive from our readers. If you would like to submit an article or pictures; of led grow lights or if you would like to comment on a current article please send submissions and comments or questions to angela@led-grow-master.com You are receiving this email because you subscribed at led-grow-master.com If you do not wish to receive this newsletter :Request your name removed by emailing angela@led-grow-master.com Contact LED Grow Master Global: Admin@led-grow-master.com |
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| September 1, 2008 Volume 3, Issue 9 |
Most farmers today use some sort of 'light sensor' to optimize plant placement and spacing. Everybody knows plant quality increases as the daily light integral (DLI) in the greenhouse increases, meaning more light equals better crops providing other environmental variables are in balance such as temperature, humidity, and CO2 concentration. When using a meter to measure foot candles, remember the meter is gathering mostly green and yellow wavelengths, which are the colors humans perceive as 'brightest'. When using a meter to measure PAR, remember green and yellow hog up to 50% of your reading. Light meters express the amount of measured light using different variables including PAR (measured in micro-moles of quanta per second per square meter µmol s-1 m-2 (measuring 400nm-700nm) for plants, Foot candles Lux (for people), and in Watts/m2 (for solar radiation). Meters displaying foot candles are measuring mostly the green and yellow quanta from a light source. Meters displaying µmol s-1 m-2 for PAR are measuring all the visible light between 400 and 700 nanometers, as this is the range of quanta used by plants for photosynthesis. A 42-LED Panel filled with green "550nm" LEDs will register up to 20 times the FCs as the same Panel filled with "680nm" red LEDs. Light meters are designed to measure broad spectrum light (Sunlight, HID, Fluorescent), and not LED grow lights. Green is perceived brightest by the human eye, so it makes sense to measure foot candles for offices, classrooms, and assembly benches, but not for greenhouses. Since HIDs and fluorescent tubes were originally developed as area lighting, these less absorbed wavelengths came along for the ride when the lights were re packaged for the greenhouse industry in the 70's. LGM-5 covers up to 12sqft per 9 watt bar in a greenhouse, and up to 1ft x 3ft over plants indoors. The new lighting variable is LGM5. Get it, grow it, love it. -J9
Until about 200 years ago the only man-generated light source was fire, and it's only in the last 100 years that electrically operated man-made light generators became practical for widespread use. Innovation has continued until today, giving us many types of lamp technologies. From the original glowing filament (incandescent bulbs) to glowing plasma (fluorescent tubes), arc lamps, metal halide bulbs, and LEDs, man-made light generators are available for many purposes including growing plants. To the human eye most man-made light generators seem to create light that's very similar to sunlight. Yes, there are the odd ball lamps like high or low pressure sodium that have a very skewed (and yellow) cast to their light, but for the most part man-made light generators produce some sort of white light that imitates the appearance of sunlight. But the beautiful colors of a rainbow soon show that sunlight and light from man-made light generators is very different. Sunlight contains all of the colors of light, in roughly equal proportion. This can be readily seen by shining sunlight through a prism to separate its light into a continuous rainbow of colors. What do we see if we shine the light from a man-made light generator through the same prism? For incandescent light sources like common household light bulbs we also see a continuous spectrum of light, but one that isn't as even, and has very little blue light but a great deal of red light. The light from most other types of lamps will show narrow areas of bright color, broader areas of very dim colors, and many dark bands where some colors aren't produced at all. Most LEDs, which have a very narrow spectral output, will typically show only a very narrow band of a single color. Incandescent lamps, while producing a continuous spectrum of light, generate very little blue light, making them a poor source of plant growing light. The other types of lamps such as fluorescent tubes and HID lamps, can be modified to produce more colors of light plants like, making them a bit better for growing plants. But all of these types of lamps generate a lot of light in colors plants don't use very efficiently. They also waste a lot of energy as heat, making them even less efficient. LEDs, as discrete sources of nearly monochromatic light with high electrical efficiency, offer a unique opportunity to designers of plant growing lamps. Instead of starting with an existing lamp designed to light rooms for people, such as a fluorescent tube or HID lamp, an LED grow lamp designer can select LEDs that generate exactly the colors of light needed to target whichever plant pigments are chosen. Designers are able to add as many LEDs of each color produced in the proper proportion. Finally, the individual LEDs can be arranged in whatever pattern desired to create the final lamp design. By leaving out colors of light that are useful for human vision but not useful for plant growth, even greater levels of efficiencies are achieved compared to other types of grow lights. --CEO SolarOasis Copyright 2008 ALL RIGHTS RESERVED LED Grow Master Global, LLC |
| LED Grow Lights For Farmers |
| Determining DLI |