LED lighting is firmly established in our lives, LED light bulbs are already sold, even in grocery stores and on the economic and shelves building supermarkets LED lamps longer than conventional incandescent and compact fluorescent (energy saving), together combined.
Unfortunately, manufacturers often deceive consumers, pointing to the package excessively high values of light and incandescent equivalent. You buy a lamp that says "600 lumens, equivalent to incandescent 60W", bring it home, turn on and realize that it is clearly shines dimmer than a 60-watt incandescent bulb. Fortunately, according to the law on the rights of the consumer LED lamps can be returned to any store within 14 days (and in many supermarkets and within 30 days, 60 days or even years). Return is possible due to the fact that the light (including LED) is still not considered to be a complex technical product.
In order to understand how much is actually light it gives light to be measured its luminous flux.
Typically for measuring the luminous flux (the total amount of light, which gives the lamp) uses expensive laboratory equipment (goniophotometer, measurement integrating sphere), which costs tens of thousands dollars. I invented a way to accurately measure the luminous flux, spending just 87 rubles.
The main problem in measuring the light flux - the brightness unevenness of light in different directions for different types of lamps. Some lamps more light forward, some more light in the hand, some nearly uniform light in all directions.
To measure the need to somehow get the average value of the lamp brightness. The integrating sphere lamp placed inside the sphere covered sverhbeloy matte paint of barium sulfate. The light is repeatedly reflected from the walls of the sphere and falls on the sensor. Goniophotometer rotates the lamp in the horizontal plane, makes a plurality of brightness measurement at each rotation and calculates the total amount of light, which gives the lamp. We'll do easier.
We will need a lamp with a spherical matte plastic cap. This matte cover and will average the brightness of the lamp radiation in different directions. such a lamp can be bought for 87 rubles Leroy Merlin stores. In the picture there is another lamp with a glass canopy - do not pay attention: in fact, it is necessary to own stores.
The exact naming lamp "The lamp of the NBB-60 (direct base) ball of plastic, white", producer company "Axiom", Moscow.
As the luminance meter (light meter), you can use almost any smartphone on Android. Most smartphones have a light sensor (located above the screen), which is used to adjust the screen brightness according to ambient lighting.
In Play Market has many programs-luxmeters I recommend installing a simple and convenient program Sensors Multitool. After starting the program go to Light tab, and see the value of lighting. Light meter for all smartphones are not calibrated and different smartphone it will show a completely different values, which may differ from the real two, but the accuracy of our measurements, it does not affected.
Mounting to any surface (I used a piece of plywood). Smartphone attach two rubber bands to package milk, or juice.
For the measurement, we need a reference lamp. I recommend to use the lamp IKEA 600 Lm 303.059.76 LED1466G9. This lamp has a luminous flux, which corresponds exactly to the claimed very small difference of luminous flux in different instances.
Of course, you can use incandescent bulbs, but it is important to remember that the first luminous flux of incandescent lamps varies greatly the voltage in the network, and secondly different instances of Russian and Belarusian enterprises lamp production can vary greatly according to the light flow. However, you can always find out more or less light makes LED bulb compared to an incandescent lamp.
Spun cover, turn on the lamp, place the smartphone on the other hand is fixed lamps, run the program. We calibrate our measurement system: shift the package with fixed smartphone so that the light meter shows exactly 600 smartphone Suite (if as a reference we Lamp 600 lumens). Now unscrew the standard lamp and the lamp is screwed, we want to be measured without changing the distance between the lamp and the smartphone. Smartphone show a value that will correspond to the measured light flux of the lamp.
I tested this simple measurement setup on the seven lamps with a luminous flux of 200 lm to 1000 and two smartphones - Sony Z3 Dual and ZUK Z1. Deviation was 1-15%.
In LED lamps is one feature - as warm they reduce light output by 11-12% within half an hour. We measured the lamp immediately after turning on, but as the light standard and was cold, our whole measuring system was more or less accurate.
Improve the accuracy of the measurement can be if, instead of a smartphone to use any light meter. Suitable even the cheapest Chinese for $ 10. It can be calibrated badly, but do not affect the accuracy of our measurements it again. Standard lamps and those lamps, the luminous flux of which we want to measure, it is best to warm up for half an hour. Light meter is necessary as hard to fix and position at a distance from the lamp, so that he showed as much luxury as lumens lamp gives reference.
I measured the same seven lamps using a light meter-pulsmetra Lupine.
Accuracy of measurement has become much higher - 0-3% of all errors.
Note that all official accredited laboratories also have differences in the measurement. In the picture below the measurement results of the luminous flux of the same lamp in 54 different laboratories. The average difference was 3%, maximum 26%.
That's right, "on the knee", I was able to achieve precision measurements, which can boast not all laboratories.
© 2016 Alex Nadozhin
p.s. This article I wrote for the section "Workshop" 3DNews site and initially it was published there: http://www.3dnews.ru/931505.
The main theme of my blog - Equipment for human life. I write reviews, share experiences, talk about all sorts of interesting things. And I'm doing stories of the interesting places and tell about interesting events.
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