Induction lamp and mesopic vision

Why induction lamp lighting is better than that of the sodium and metal halide?

Or what is the photopic and mesopic vision?

If you carefully read our previous publication on the website Arsenal-A, you probably already found the answer to this question, but one who, for some reason they have not read, or he had no time to do it, in this article, you will find the most comprehensive the answer to it.

Let’s take a closer look photo1 below for details. This studio photography for different types of light sources: incandescent lamp (halogen lamp), induction lamp, fluorescent lamp, metal halide lamps with ceramic burner (CMH), a mercury lamp (DRL), metal halide (MH), high pressure sodium lamp (HPS) , a low-pressure sodium lamp (LPS).



  • color rendering index CRI SVETlichny
  • color rendering index CRI SVETlichny

That we will see?

When illuminated with light from the studio Induction Lamp, color of objects are in the studio are the most natural, and do things better distinguishable.

Why is this happening?

Attention! The material presented below, is full of technical terms that are understandable to specialists, but without them it is impossible, as a matter of serious and get it right and the scientists and specialists lighting.

If you find it difficult to read, you can learn the basic findings of the end of the article, they are highlighted in bold.

Clarification of this issue of the American officers engaged in scientific research center Lighting Research Center (LRC). They conducted a series of studies onmesopic street lighting.

Were chosen the most modern types of light sources used in the United States for the lighting of streets and highways.

The studies were conducted in Groton, Connecticut.

Compared Street Lighting with 100 W high pressure sodium lamp (HPSInduction lamp 55W, 70W lamp with ceramic metal halide lamp.

The illumination of these light sources is clearly visible on the submitted photo1  above.

Studies have shown that the coverage of Induction and metal halide Lamp, with the spectrum of white light is optimal for human vision in low light conditions (dusk and night).

It turned out that the human eye retina contains two types of receptors, the cells which appear as cones and as Sticks, transmitting the incoming video signals through the eyes to the brain. 

Officially, the current system is still photometric measurements allows to determine the amount of light regardless of the conditions and time of day. It is based on modeling the reaction function of cone cells of human eyes, which are mainly used in daylight (photopic) Based on this principle and sensitivity of modern instruments for measuring light — Luxmeters.

Coli cells are responsible for night (scotopic) A person’s vision. But the collaboration of these two types of cells — rods and cones, provides a person twilight, so-called mesopic  vision, so that he could see well at night and at dusk.

Given these features of the structure and sensitivity of the human eye, scientists have concluded that it is possible to reduce the brightness of the lighting, as measured by traditional methods (light meter), without loss of visual quality or even improve, given the features of mesopic vision. In other words, the light source should take into account the particular susceptibility and cones and rods.

It is therefore concluded that it is necessary to apply a cold light lamp and a short wavelength. 



  • Color temperature SVETlichny
  • Color temperature SVETlichny


LRC to develop a standardized photometric systems (UFS), as a means of visual modeling of visual perception in low light or low light conditions. The validity of the conclusions made by the fundamental confirmed in experiments with the use of this system. It was found that the use of UVC actually improves visual perception even greater extent than they assume, from changes in the spectrum and in the illumination level.

Studies have shown in practice that target recognition by people moving along the road lighting is better for induction and IPF lighting (metal halide lamps) than NLVD lighting (high pressure sodium lamps). Studies have also confirmed that the use of UVC, improves vision, as well as  reduce energy consumption.

With UFS calculated such factors as the brightness of the pavement by covering the new settings, to this end, measured illumination of the road and its reflection coefficient, which were introduced in the UFS, which would define the parameters of equivalent lamps and equivalent visible (visual) features.

The purpose of this project to determine the possibility of the two light sources, selected and configured with the features of light vision, to provide the necessary visibility, reliability, and security of brightness, similar to sodium lamps (NLVD) light sources, while reducing energy consumption by at least 30%.

Another goal of this project was the task in determining the economic feasibility of such systems as those that have been established in the city of Groton, in pieces. Connecticut.

 Compared the three lighting technologies.

Two of them — induction (lamp power 55W, 6500K, duty. S / P 2,88) and metal halide with ceramic arc tube (70W, 4000K, S / P = 1,6), chosen on the basis of economic feasibility, as they can reduce power consumption with the same characteristics of visual perception of brightness, in accordance with UVB.

In the experiment, it was determined that the luminous flux of induction lamps is not affected by ambient temperature changes, as well as their launch in cold weather is stable. Because of the very long life (over 100,000 hours), significantly reduces the cost of maintenance and repair.

To demonstrate the light of these systems were chosen two sections of city streets.

Street Meridian — Two-lane road with car parking on both sides of the road, which has an asphalt surface, a width of 12m.



  • street lighting sodium lamps
  • street lighting sodium lamps


Street lights positioned at a distance of 36.5 m from each other and at a height of 7.6 m due to heavy foot traffic. NLVD 100W lamps with induction lamps and 55W, the average luminous flux 8460Lm 3300Lm and respectively, and the average illuminance 8.72 and 2,69 Lux (as measured LRC).



  • Induction lighting fixtures
  • Induction lighting fixtures


Street Shennecossett Road.



  • Sodium lighting fixtures
  • Sodium lighting fixtures



The width of the road is the same, but the location of street lights a few more — the distance between them is 85m. Lamps with NLVD and IPF with Ceram. burner. Photo below.


  • Metal halide lighting fixtures
  • Metal halide lighting fixtures




Lamps of 100W (8460Lm, Illumination 8,72 Lux), and 70W (4150 Lm, LIGHT. 3,1 Lux).

In the course of the experiment, it became apparent that the use of induction and metal halide lamp (with ceramic. Burner) is more appropriate than a lamp with a 100W sodium lamp NLVD. Since the average luminance of the pavement illuminated NLVD (S / P = 0,63) in photopic vision = 0.21 cd/m2, and in mesopic conditions is 0.17 cd/m2. And with induction lamp lighting photopic luminance of 0.08 cd/m2, while the mesopic — the same 0.17 cd/m2, like sodium lamp, power 100W.


  Mesopic lighting in cd/m2 Coefficient of S / P Photopic lighting in cd/m2 Luminous Flux, Lm Lamp Power, W
NLVD 0.17 0.63 0.21 9500 100
Induction lamp 0.17 2.88 0.08 3620 55

  Compared with NLVD and IPF figures were as follows: metal halide lamp as the source of white light, was more suitable for street lighting. Here’s why: The average brightness of the light 70W ceramic with IPF. burner was 0.07 cd/m2, which is considerably higher than NLVD fixtures — 0.03 cd/m2.


  Mesopic lighting in cd/m2 Coefficient of S / P Photopic lighting in cd/m2 Luminous Flux, Lm Lamp Power, W
NLVD 0.05 0.63 0.07 9500 100
IPF 0.05 1.6 0.03 4070 70

  However, it is known that MHL lamps eventually there is a significant decrease in the luminous flux being faster than NLVD. This means that the results obtained during performance of the experiment light significantly decrease with time.

Assessment of the quality of street lighting.

Residents of the streets on which the experiment was conducted, questionnaires were sent, it was proposed to evaluate the visibility, security, reliability, as well as the brightness and color of the light fixtures installed.

Residents of the street Shennecossett Road noted the distinct advantage of using 70W IPF and reported in this light feel safer and better to see than the light 100W NLVD. But do not forget that the evaluation of the illumination was carried out at peak brightness and light metal halide lamps, which decreases with time.

Assessing the economic feasibility of

Maintenance and repair — an important cost item for utilities serving urban lighting system. They are second behind energy consumption.

 Summing up these figures, during the experiment identified  the life cycle cost of each lighting systemThe lowest was in the induction lamp  55W — 1,549 dollars for IPF 70W — 1824,21 dollar and NLVD 100W — 1832,65 USD


Based on the data obtained in the course of the experiment, we can draw the following conclusions:

— lights with sodium vapor lamps should be replaced by white light sources with a high coefficient of S / P, with a color temperature of 6500K and a luminous efficiency of more than 65-70Lm / W.

In low light intensity of 0.1 cd/m2, saving email. Energy can be as high as 40-50%. At higher rates of brightness — 0.3 cd/m2, the savings will be around 30%.

— induction lamp with lamp 55W, 6500K proved the most energy-efficient replacement 100W lamps used with NLVD for street lighting.

— IPF 70W — just as a good replacement of street lighting 100W NLVD, however, by a whisker.

— NLVD lights can also be replaced, and the white light emitting diodes (LED), with the only caveat that their light output is really high, the service life of more than 50 thousand hours, and cost — economically justified (in the near future is still unlikely).

— recommended as well when calculating the required wattage that will replace the existing lighting system (for example, NLVD), to apply the system of calculation that uses the ratio S / P, which will really appreciate the equivalent visual perception illuminated objects *.

* This article draws on research materials: Mesopic Street Lighting Demonstration and Evaluation Final

Report / / / researchAreas / pdf / GrotonFinalReport.p





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