LEDs light up the future in Amsterdam

This year the LED2007 Conference & Showcase will shine its light on all applications with LED and its technological possibilities and challenges. Hence the subtitle: ‘Light on the move’. This year the topics of the conference are Solid State Lighting, OLEDs, LED Optics and Thermal design of LED Applications.

At this conference, there will be more attention for the next generation of high power LEDs of the lighting industry. End users will present market developments with a future perspective.

The conference program informs the target groups about the developments of LEDs and about the strategic chances LED technologies can form for the defined application segments:

  • Indoor
  • Outdoor (Beautification)
  • Industrial Lighting
  • Outdoor (Public Lighting)
The LED2007 Conference & Showcase takes place in Eindhoven, the Netherlands on February 13, 2007 and is subtitled "Light on the move". The event will look at new LED applications, and the technical possibilities and challenges now and in the near future.

LED2007 program

The program of LED2007 consists of six parts:

  • A high-quality conference where current market experiences are exchanged with visions and new developments;
  • Showcase, where exhibitors present their products and developments.
  • Pavilions on the Showcase, where knowledge institutes, sector organisations and related organisations present themselves;
  • Technological schools and demonstrations on OLEDs, technical developments of LEDs, secondary optics, thermal design, electric design.
  • Scientific and application poster sessions in LEDs and OLEDs.
  • Parallel access to the Photonics2007 Conference.

  • LED2007/Photonics2007 Showcase

    At the LED/Photonics Showcase, companies and research organisations present their latest and future products to all conference attendees. Registration, breaks, lunch and the buffet dinner will all take place at the Showcase. During the day and evening the conference participants will be given ample opportunity to get more closely acquainted with the various companies and research institutes and their products or research.

    At the end of the conference the reception and dinner buffet will provide excellent networking opportunities.

    Visit the LED2007 website for more information on the program, registration, venue and other activities.

    New LEDs conference in Belgium: LED4Europe

    LED4Europe in Brussels aims to boost LED development

    A new conference in Brussels in February aims to assist LED companies to develop partnerships and collaborations.

    The two main goals of LED4Europe, which takes place in Brussels, Belgium on February 8-9, 2007, are to inform and stimulate partnering and collaboration between companies and research centres, while also increasing awareness of LED developments in Europe.

    The event includes a Congress, and Exhibition, and a unique Partnering Event. LED4Europe is organized by the Brussels Enterprise Agency and the Brussels Innovation Relay Centre, and is supported by AGORIA, CRIF, LEDs Magazine and the Innovation Relay Centre Network.

    LED4Europe provides product manufacturers, lighting consultants, architects and design engineers unique networking opportunities during the Congress and Exhibition show but also during the Partnering Event.

    The LED4Europe Congress and Exhibition takes place on Thursday February 8, and will include a selection of expert speakers from companies and organizations such as EREA, INSTA, the European Patent Office, Osram and Future Lighting Solutions (and LEDs Magazine).

    The LED4Europe Partnering Event, which takes place on February 8 and 9, features private, pre-arranged one-on-one meetings between companies and research centre executives. This is an unparalleled opportunity to conduct many meetings in one place.

    Companies will present their technical or business offers and requests in an on-line catalogue. Interested partners may book an appointment for a confidential face-to-face meeting at the Partnering Event.

    The Technical Offers and Requests published in the catalogue covers the following LED technological topics:
    LEDs for lighting, signage and display products
    • LED cooling technologies
    • LED power supply, driving and control software
    • LED specials optics
    • LED chip manufacturing and manufacturing equipment
    • LED measurements instruments and facilities

    The LED4Europe event takes place in the Diamant Building, B-1030 Brussels, on February 8-9, 2007. The participation fee of 130 EUR covers the entry to the Congress and Exhibition venue and the lunch.

    For more information, contact L. Lamberts on tel. +32 2 422 00 22 or by email at lla@abe.irisnet.be

    DIY LED Useable Light Tool

    Building a LED Grow Light array can be tricky and there are many factors that one should take into account before tossing your hard earned duckets into the High Brightness LED (HB-LED) silicon frying pan

    Below is an excellent tool that can help you to create your own LED Grow Light array. Here is the Light Tool that you can use when evaluating high-power LEDs for building your own HB LED Plant Grow Lights, it should work with other makes and models of LEDS.

    [ Using the LED Useable Light Tool will require filling in an easy sign up form. ]

    Below are some sample screen shots:

    Often, when evaluating high-power LEDs, typical flux values, which are measured at a junction temperature of 25°C, are considered only. Such an analysis is incomplete and inaccurate for determining the expected level of light from the light source in a "real world" environment.

    The purpose of this tool is to provide a true "real world" evaluation and comparison of high-power LEDs by taking into account the effects of 7 critical relationships (see diagram):

    Link updated!

    Wavelengths in LED Plant Grow Lights

    Here is a very small list of wavelengths (nm) that can be used for selecting LEDs when building your own LED Grow Lights or Solid State Plant Lighting:

    200 - 280 nm UVC ultraviolet range which is generally harmful to plants. LEDs in this spectrum are non-existant or very expensive.

    280 - 315 nm Includes harmful UVB ultraviolet light which causes plants colors to fade. UV LEDs in this range are now available and coming down in price.

    315 - 380 nm Range of UVA ultraviolet light which is neither harmful nor beneficial to most plants.

    380 - 400 nm Start of visible light spectrum. Process of chlorophyll absorption begins. UV protected plastics ideally block out any light below this range.

    400 - 520 nm This range includes violet, blue, and green bands. Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis. (promotes vegetative growth)

    520 - 610 nm This range includes the green, yellow, and orange bands and has less absorption by pigments.

    610 - 720 nm This is the red band. Large amount of absorption by chlorophyll occurs, and most significant influence on photosynthesis. (promotes flowering and budding)

    720 - 1000 nm There is little absorption by Chlorophyll here, but Phytochrome uses a nice portion. Flowering and germination is influenced. Near and above the higher end of the band is the Infrared spectrum, which can also be heat and could cause elongation or affect water absorption/transpiration.

    The ratio of red (660nm) to far red (730nm) in sunlight is about 1.2:1

    Many of these plant pigments have dual wavelength peaks that can be activated with led light combinations:

    Beta-carotene 450nm 480-485nm dual peak
    chlorophyll a 430nm 662nm dual peak
    chlorophyll b 453nm 642nm dual peak
    phycoerythrin 590nm single peak
    phycocyanin 625nm single peak

    670nm and 700nm for the Emerson effect.

    Wavelength and Pigment Absorption image below borrowed from http://www.estrellamountain.edu/faculty/farabee/biobk/pigment.gif

    If you have additional information that you feel that could help other LED Grow Light researchers and should be added please send it to: ledgrowlights[remove extra stuff and brackets](@ googles)gmail.com

    Measuring LED Grow Lights, lux, par and lumens what are they?

    Unlike LED Lights, Artificial light sources are usually evaluated based on their lumen output. Lumen is a measure of flux, or how much light energy a light source emits (per unit time). The lumen measure does not include all the energy the source emits, but just the energy with wavelengths capable of affecting the human eye. Thus the lumen measure is defined in such a way as to be weighted by the (bright-adapted) human eye spectral sensitivity. If we plot this sensitivity as a function of the wavelength of the light (building the so called photopic curve), we see that it has an approximately bell shape, peaking up at a wavelength of around 550 nanometers (nm), the "green" region of the light spectrum, and decreasing at both longer (red) and shorter (blue) wavelengths. See the plot here. The consequence is that two light sources that emit the same total amount of energy can have vastly different lumen ratings, depending on how much of that energy is concentrated around the 550 nm region.

    Another quantity often quoted when talking about light output is lux. Lux is a measure of illumination, not flux. Flux refers to the light energy that leaves the source. Illumination refers to the light energy that reaches the receiving surface. Lux is equivalent to lumens/m2. Lux cannot be computed only from the know data of a light source. Additional information regarding the illumination geometry, reflectors, distances, intervening media (glass covers, etc.) must be taken into account.

    Other quantities used to describe light quality associated with its visual characteristics are color temperature and color rendering index (CRI). Color temperature is defined as the temperature that a perfect electromagnetic radiator ("black body") would have to have to emit light with the same "color" as the light source in question. Higher color temperature means bluer color, lower temperature, redder color. Color temperature is expressed in degrees Kelvin (from Lord Kelvin, the 19th century physicist, and which means degrees Celsius above absolute zero). CRI measures how close to their "true color" a light source can render objects illuminated by it. A "perfect" light source would have a CRI of 100, lower values mean that the colors are shifted from their "true" hue and saturation. Many people are familiar with the color shifting that takes place when one buys clothes in a store with artificial illumination and then realizes that under natural (sun) light the colors are not quite the same. Had the store used high-CRI light bulbs that color shift would be much smaller or not noticeable at all.

    It is easy to guess from the wording in the above paragraph that these two parameters are also strongly related to the human eye response characteristics. In fact, the technical definition of the term "color" used above is directly based on psychophysics experiments performed with human subjects and standardized by the CIE (Commission Internationale d'Eclairage) about 60 years ago. In other words, color temperature and CRI are parameters entirely based on the human visual system characteristics and may carry absolutely no meaning when applied in other contexts.

    Laboratory experiments showed that the photosynthesis process that takes place in plants when submitted to intense light has a very different spectral response than the human eye. In fact, photosynthesis is the least efficient in the region around 550 nm. Most of the light capable of inducing the photosynthesis reaction is either red or blue. In other words, plant leaves mostly reflect green light, while they absorb red and blue with higher efficiency. An experimental fact that confirms this statement, independent of any laboratory measurement, is the fact that many plants look green ! Portable field instruments used to quantify photosynthesis in growing plants often exploit this fact by using as light source a pair of red and blue LEDs (Light Emitting Diode) instead of a white light source.

    The curve that results from plotting photosynthesis efficiency as a function of wavelength is named "Photosynthesis Action spectrum". It is the equivalent of the photopic curve for photosynthesis. The curve is typically double-peaked, with peaks around 420 nm (blue) and 670 nm (red) and a "valley" around 550 nm. The curve drops sharply below 400 nm and above 700 nm. The peaks are broad and not as pronounced as the central peak in the photopic curve. There is still significant response in the green region around 550 nm. See a typical curve here. Many plant species can show specific action spectra that differ markedly from that "average" curve. In some extreme cases there is no response at all in one of either red or blue regions. The important point is that photosynthesis has a much broader wavelength response than the human eye, with less dependency on specific, narrow wavelength regions. Thus, light sources that look very different to us may "look" similar to a plant. Conversely, light sources that look similar to us may "look" very different to plants, all depending on their specific spectral distributions.

    In some instances we see references to "plant growth spectrum" as well. This is not to be taken as equivalent to the action spectrum though. The action spectrum has a precise meaning in terms of quantity (in moles/sec/leaf surface area) of CO2 consumed by the plant subject to measurement. "Growth", on the other hand, can be defined in many different ways (height ? weight ? weight of dry plant mass ?) that can be even very species-dependent, so it hardly makes a good standard for comparison purposes.

    Based on the Photosynthesis Action Spectrum, light bulb manufacturers came up with fluorescent "plant bulbs". They basically emit most of their light in the wavelengths that are more efficient for photosynthesis, namely the red and blue ends of the visible spectrum. As expected, these light sources look dim to the human eye and consequently have poor lumen ratings. Also, their color temperature and CRI ratings have little, if any, meaning. After all, these bulbs were not designed to be "seen" by humans...

    The standard measure that quantifies the energy available for photosynthesis is "Photosynthetically active radiation" (aka "Photosynthetic Available Radiation") or PAR. Contrary to the lumen measure that takes into account the human eye response, PAR is an unweighted measure. It accounts with equal weight for all the output a light source emits in the wavelength range between 400 and 700 nm. PAR also differs from the lumen in the fact that it is not a direct measure of energy. It is expressed in "number of photons per second", whose relationship with "energy per second" (power) is intermediated by the spectral curve of the light source. One cannot be directly converted into the other without the spectral curve.

    The reason for expressing PAR in number of photons instead of energy units is that the photosynthesis reaction takes place when a photon is absorbed by the plant, no matter what the photon's wavelength (or energy) is (provided it lies in the range between 400 and 700 nm). That is, if a given number of blue photons is absorbed by a plant, the amount of photosynthesis that takes place is exactly the same as when the same number of red photons is absorbed. For convenience, number of photons is usually reported in the literature in micromole units, or microEinsteins. One microEinstein is equivalent to 6.02 1017 photons. Another important difference is that usually PAR is quoted as an illumination measure akin to lux, thus related to the receiving surface. PAR is typically reported in microEinstein/second/m2.

    Thus we see from the above that, to evaluate
    Solid State Lighting sources (Led Grow Lights) for use in plant applications, we cannot in principle rely entirely on an human-based criterion, the lumen rating. Unfortunately, most if not all manufacturers provide little information in that regard. Power consumption in Watts and lumen ratings are easy to get, and for many bulbs spectral plots do exist. Many of these are not depicted in physically meaningful units though (such as Watt/nanometer), making it difficult to compare different products. PAR figures are never quoted because they depend on the detailed illumination geometry, which varies from setup to setup. The Solid State lighting industry is just now starting to standardize LED measurements and reporting which will go a long way in helping to shape the emerging market for LED Grow Lights.

    Action spectrum

    Buy low cost LED Grow Lights!

    This latest article is another sign of affordable LED Grow Lights coming to a dollar store garden shop near you.

    An upcoming process for making LEDs (blue, green, white, etc.) on a larger and cheaper substrate material then currently used was recently announced:

    BlueGlass, a spin-out from the III-nitride department at Macquarie University in Australia, plans to build a pilot manufacturing facility to further develop its low-temperature deposition method, which is claimed to be compatible with glass substrates up to 8 inches in diameter.

    ..."Process temperatures are 500-700°C, making it compatible with glass, silicon and other low-cost substrates, and so avoiding the use of sapphire or silicon carbide," explains BluGlass.

    Because it avoids the use of expensive MOCVD equipment, and could be compatible with such large wafers, the method promises to allow LEDs to be manufactured at a much lower cost than currently, which could open up new markets where cost is a critical issue, such as residential solid-state lighting.

    ...If all goes according to plan, BluGlass is looking to generate revenue in a number of different ways. These include sales of the novel GaN deposition equipment, licensing of its patented manufacturing process, and the sale of GaN-based wafers and/or LEDs.

    According to the company, the growth process is also compatible with GaN alloys, as well as InN and AlN materials.

    These new cheaper LED lighting substrates will be great for lowering the cost of indoor LED Grow Lights, I can envision a future where everyone can buy LED Grow Lights and Panels.

    LED Grow Lighting units for Plant Cultivation

    These LED Grow Lighting units are not only for botany research and plant cultivation but can also be used for plant physiology or cellular and molecular biology. They look fancy and expensive, though I couldn't find pricing for these units. Lets hope the Japanese can release more Solid State Plant Lighting devices in the near future.

  • New! LED Lighting units for Botany
  • LED Grow Lights used for Photosynthesis in Refrigerators!

    Interesting if only LED Grow Lights in the orange spectrum(590 nm) are found to be useful for this application, I wonder if someone can locate or find this LED Grow Light Research and publish it online somewhere... or send it to me PLEASE... ledgrowlights[({at})]gmail.com

    Home Vitamin Factory with Solid State LED Lighting

    "Does the refrigerator light stay on or go off when you close the door? The common-sense answer is “off,” and that is what they all did until fresh thinking at Mitsubishi Electric found a reason for them to stay on—at least in the vegetable drawer..

    The company has just announced several refrigerators that boost the levels of vitamin C, chlorophyll and other nutrition-related compounds in vegetables during storage. Reflecting the consumer trend toward healthier eating, Mitsubishi Electric product planners looked for ways to actually increase the vitamin content of vegetables. Once they had the new perspective, the solution was relatively simple.

    Research showed that the light’s color was important: The orange light creates chlorophyll in vegetables without inducing them to grow. A small bank of LEDs in the roof of the vegetable drawer produces light at a wavelength of 590 nanometers (orange). Mitsubishi Electric found that after three days, the vitamin-C level in broccoli sprouts stored in their new refrigerator was 50% higher than in a conventional refrigerator.

    LEDs are perfect for this application. Being extremely energy efficient, they use almost no electricity and produce insignificant heat. Japanese consumers have welcomed the new technology by boosting sales of Mitsubishi Electric’ main refrigerator line by about 50%."

    LEDs as Grow Lights in refrigerators

    After checking out their product line up I looked at retail pricing and realized they don't give these pimped out refrigerators with LED grow lights away for free.

    Growing Tips for using LED Grow Lights and Solid State Lighting

    A list of tips for gardening with LED grow lights and low heat solid state lighting.

  • These tips come from experience, and should be considered, to insure success with LED Grow Lighting Arrays. These tips apply to general gardening, and are techniques you are already using. Now you need to develop these techniques with 90% less heat in your system.

  • Keep environmental temperatures in the range of 70F° -80F° (Lower Temp = Slower Plant Growth) (Monitor Root-zone Temp as well)

  • DON'T over water your plants (Less Heat from LEDs = Less water loss due to evaporation) (Overwattering = Slow root development = Slow and Stunted Growth and Nutrient Uptake issues)

  • Use a more porous medium = more oxygen to roots = higher plant metabolism.

  • Water plants once, let them run low on water = plant water usage rate for your particular plant species (Under LEDs).

  • If you keep the root medium saturated = no need for plant to develop larger root system = stomata closure, slow and stunted growth, and symptoms of overwattering.

  • Monitor your CO2 levels (Some LED grow lights contain LEDs that emit a large amount of plant specific usable light, therefore may require slight augmentation of CO2 levels (300-500 PPM)

  • Start with a lower amount of nutrient (400-600 PPM) or 1/2 the Oz/Gallon, or ml/per Liter recommendation on your plant foods.

  • On fruiting plants: Reduced photoperiod = plant stress = more flowering.

  • Remember, It doesn't look like much light to you, but it is very much light to your plants.

  • Dictionary of Lighting and Horticulture Terms

    Dictionary of Lighting and Horticulture Terms

    The efficiency of a particular plant molecule at absorbing wavelengths of light to conduct photosynthesis. LEDs are very efficient at producing the wavelengths of light that plants can best use.

    A system where plant roots are in an environment saturated with fine drops (a mist or aerosol) of nutrient solution.

    The unit used to measure the strength of an electric current.

    The cultivation of water plants and animals for human use or consumption.

    Is the integration of aquaculture and hydroponics.

    The luminous discharge of electricity between two electrodes in HID lighting.

    A transfer of electricity across two electrodes (anode and cathode), characterized by high electrode current densities, and a low voltage drop at the electrode.

    The enclosure which contains the luminous gases, and also houses the arc.

    organisms which make their own food using photosynthesis.

    An auxiliary piece of equipment designed to start, and to properly control the flow of power to gas discharge light sources such as fluorescent and high intensity discharge lamps. In metal housed systems, it is composed of the transformer, capacitor, and connecting wiring; sodium systems require an ignitor in addition to the transformer and capacitor.

    An industry code indicating that the bulb is to be operated only in a base up position.

    A colorless, odorless, incombustible gas, somewhat heavier than air that is a product of respiration and combustion.

    The two primary pigments involved in photosynthesis. These two molecules most efficiently absorb light at the red and blue ends of the light spectrum.

    Chloroplast are like a container that contains chlorophyll.

    An abnormal yellowing or veining of the leaves. Some times caused by nutrient deficiencies.

    A bulb of a certain spectrum type (e.g. sodium) specially designed to operate while used in the fixture/ballast of a different type (e.g. metal halide). The most popular conversion bulbs, by far, are sodium conversion bulbs, which allow one to have the sodium spectrum while still using a metal halide system.

    A specification of the color appearance of a light source, relating its color to that of a blackbody radiator, as measured in Kelvin (K). CCT is a general measure of a lamp's "coolness" or "warmness."

    A method for describing the effect of a light source on the color appearance of objects, compared to a reference source of the same color temperature (CCT). The highest CRI attainable is 100. Typical cool white fluorescent lamps have a CRI of 62. Lamps having rare-earth phosphors are available with a CRI of 80 and above.

    The portion of a HID outer bulb located opposite the base (the neck and threads).

    The spring-like brackets which mount the arc tube within the outer envelope (bulb).

    A lamp that produces light by discharging an electric arc through a mixture of gases and gaseous metals.

    Filaments located at either end of a discharge lamp that maintain an electrical arc between them. See arch discharge.

    The electrical fitting used to contain the electric components of a lighting system.

    A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. Fluorescent lamps are good for starting seedlings and rooting cuttings, but do not have enough intensity to sustain aggressive growth in plants in the later stages of life, and are not efficient enough in their conversion of electrical power to lumens of light output.

    A standard measurement of light intensity, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. More simply, one foot-candle of illuminance is equal to the light emitted by one candle at a distance of one foot.

    The number of waves, or cycles, of electromagnetic radiation per second, usually measured in Hertz (Hz).

    GROWTH INFLUENCING FACTORS (GIF) – most important GIF is light.

    A short name for the tungsten-halogen lamp. Halogen lamps are high-pressure incandescent lamps, containing halogen gases such as iodine or bromine which allow the filaments to be operated at higher temperatures and higher efficacies. While excellent for home lighting and similar applications, halogen lamps are not effective or efficient as grow lights, due to their limited spectrum and high operating temperatures.

    The popular acronym for High Intensity Discharge.

    A general term for mercury, metal halide, and high-pressure sodium lamps. HID lamps contain compact arc tubes which enclose various gases and metal salts that are operating at relatively high pressures and temperatures.

    High-pressure sodium lamps operate by igniting sodium, mercury, and xenon gases within a sealed, ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

    The reflective cover used in conjunction with a HID lamp. The more reflectivity a hood can provide, the more effective it is.

    An industry code indicating that the bulb is to be operated in a horizontal position.

    The art or science of growing flowers, fruits, vegetables or shrubs, esp. in gardens or orchards.

    The area immediately under a HID lamp where the light intensity is strongest. Hot spots cause uneven growth, but can be remedied by using light.

    The length of time required to bring a HID lamp to 90% light output after a short power interruption.

    The growing of plants without soil. A nutrient solution provides food and water for the plant.

    A component of the ballast necessary for the starting of the bulb in sodium systems.

    The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (lx) or foot-candles (fc).

    The act of illuminating, or state of being illuminated. This term is often used incorrectly in place of the term illuminance to denote the density of luminous flux on a surface.

    A light source which generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it. Incandescent lamps are the most familiar type of light source, with countless applications in homes, stores, and other commercial settings. Light is produced by passing electric current through a thin wire filament, usually a tungsten. Incandescent lamps are totally ineffective as grow lights; they have very limited spectrum, and are very inefficient in their conversion of electrical power to lumens of light output (lumen-to-watt ratio). They also put off far too much heat per watt to use in horticulture, even if the above-mentioned problems did not exist.

    A term referring to the magnitude of light energy per unit; light intensity diminishes evenly as you get further from the source.

    The unit of measurement to express the color (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature). A standard clear metal halide HID lamp has an average Kelvin temperature rating of 4,000 K.

    A unit of electric power usage equal to 1,000 watts.

    A measurement of electrical energy. A kilowatt hour is equal to 1,000 watts of power used over a period of one hour.

    An electrically energized source of light, commonly called a bulb or tube.

    A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions.

    The decrease over time of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors.

    Generic term used to describe a discharge lamp's starting characteristics in terms of time to come to full output, flicker, etc.

    Radiant energy which can be sensed or seen by the human eye. The term generally applied to the visible energy from a source. Light is usually measured in lumens or candlepower. When light strikes a surface, it is either absorbed, reflected, or transmitted. Visible light is measured in lumens.

    Produce light of specific wavelengths which can be selected to best meet the needs of growing and flowing plants.

    A motorized device which moves a HID lamp back and forth across the ceiling of a grow area to provide more even distribution of the light.

    A measurement of light output; refers to the amount of light emitted by one candle that falls on one square foot of surface located at a distance of one foot from the candle.

    A complete lighting unit, consisting of a lamp or lamps, together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to as a "fixture."

    A standard unit of illuminance. One lux is equal to one lumen per square meter.

    A high-intensity discharge lamp in which the light is produced by arcing electricity through a mixture of metal halides. The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and "bushiness," while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.

    The oldest member of the HID family, mercury vapor lamps work by arcing electricity through mercury vapor. While more efficient than incandescent, halogen, and fluorescent lamps, mercury vapor lamps have the least efficient lumen-to-watt ratio of the entire HID family. This, combined with an improper color spectrum for horticultural applications, makes mercury vapor lamps a poor choice for a grow light.

    The narrow, tubular end of the HID bulb, attached to the threads.

    OXYGEN (O)
    A colorless, odorless, tasteless, gaseous chemical element.

    A lighting distribution control device that is designed to redirect the light from a HID lamp in a specific direction. In most applications, the parabolic device directs light down and away from the direct glare zone.

    The relative periods of light and dark within a 24-hour period. Also referred to as daylength.

    The growth process by which plants build chemical compounds (carbohydrates) from light energy, water, and CO2. (Carbon Dioxide).

    The gravitation of a plant part toward a light source.

    Are chemical compounds which reflect only certain wavelengths of visible light. This makes them appear "colorful". Flowers, corals, and even animal skin contain pigments which give them their colors. More important than their reflection of light is the ability of pigments to absorb certain wavelengths.
    In plants, algae, and cyanobacteria, pigments are the means by which the energy of sunlight is captured for photosynthesis. However, since each pigment reacts with only a narrow range of the spectrum, there is usually a need to produce several kinds of pigments, each of a different color, to capture more of the sun's energy.

    Measure of alkalinity or acidity of nutrient solution.

    The term sometimes used to refer to the reflective hood of a HID lamp.

    The measure of the reflective quality of a surface; the relative ability of a given surface to reflect light away from it without absorbing, diffusing, or otherwise compromising the light's quality, intensity, and spectrum.

    The threaded, wired receptacle that a HID bulb screws into.

    High-pressure sodium lamps operate by igniting sodium, mercury, and xenon gases within a sealed, ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering, and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

    A sodium bulb which, according to the manufacturer, Philips Lighting, produces 30% more blue light than standard sodium bulbs. The 430-watt SON AGRO also emits 6% more light than the standard 400-watt sodium lamp.

    The series of colored bands dispersed and arranged in the order of their respective wavelengths by the passage of white light through a prism. The six main colors of the spectrum are red, orange, yellow, green, blue, and violet.

    The redirection of incident light without diffusion at an angle that is equal to, and in the same plane as, the angle of incidence.

    A unit solid angle on the surface of a sphere equal to the square of the sphere's radius.

    The component in the ballast that transforms electric current from one voltage to another.

    U (for UNIVERSAL)
    An industry code indicating that the bulb can be operated in any position: Horizontal, Vertical (base up), or any other.

    Light with very short wavelengths, out of the visible spectrum.

    A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized UL, and other, standards. A UL listing is not an indication of overall performance.

    The distance, measured in the direction of progression of a wave, from any given point to the next point characterized by the same phase.

    First posts in the LED grow light links section!

    Here are some useful links with *more* to come...