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An office desk lamp should render text and images at the work area with even lighting and the best possible contrast.

What is the state of the art desk lamp?

First think of what we should demand of the lamp.

Ideally, it illuminates your reading area without causing any kind of glare, whether direct or reflected. It should not take up a lot of space, and it must not obstruct your field of vision, neither over the computer screen, nor the reading area. No glare shall be directed to others, even if they work at a lower table height than you. The lamp should be adjustable to any task, whether you have a vertical or a horizontal reading area, or if it is placed to the right or left or in the center.

In a few workplaces, some of those demands might not be crucial, but if the lamp should be adaptable to all work conditions, it must meet all the above requirements.

There are such lamps. A good desk lamp can be used above eye height without causing direct glare. A good desk lamp can be adjusted to a position where it will not cause indirect glare, and from that position, it can be pointed toward the reading area.

The pictures are taken with the reading area to the left, so that direct comparison can be made with asymmetric desk lamps. Right-handed persons might prefer the reading area and lamp to the right. The freely adjustable lamp, grey in the middle, works equally well on either side.

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Specular parabolic louvre

The hallmark of an ergonomically sound desk lamp is glare protection, and the best lamps have a specular parabolic louvre that protects against direct glare from the bulb or reflector. With a specular parabolic louvre, the lamp can be raised to above eye height without causing direct glare. From a high position it will illuminate a larger area, and it will not obstruct your view toward the computer screen.

The parabolic louvre is built up by cells with slightly concave specular walls. The louvre guides the light and prevents stray light from reaching your eyes.

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A glare-protected lamp will not dazzle coworkers at lower table height

A lamp without glare protection must be placed below eye height lest it will cause direct glare. A lamp without glare protection will also more likely cause reflected glare from the computer screen. Without proper glare protection, coworkers at lower table height will be dazzled by the lamps that are placed on higher desks.

A specular parabolic louvre can eliminate such hassles.

The asymmetric lamp has no glare protection. It causes direct and indirect glare, both to the user and to those around.
The luminance toward the coworker above is 30 000 cd/m2.

With glare protection you can work at different table heights without risking direct glare. The luminance level here toward the coworker is only 30 cd/m2.

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A good desk lamp needs no detailed instructions

It is simple to position a desk lamp properly. You just set it to the position you prefer. If you notice reflected glare, move the lamp head to where it does not cause glare, and from there, point it toward your reading area.

In fact, positioning the lamp well is so simple, that most users succeed in doing so, disregarding the contraproductive instructions . The reason why asymmetric desk lamps are never positioned according to the manual is that it does not work, and that the user has found a better position for the lamp. However, even if it is possible to place an asymmetric desk lamp where it does not produce glare, it can usually not be directed to where you need the light, and it still may cause direct glare.

A lamp with a specular parabolic louvre will not cause any direct glare, whether to the user or anyone else, as long as it is pointed toward the reading area. You will soon learn what positions work best; those to avoid are where part of the reading area is between you and the lamp. That is where the asymmetric lamp instruction failed, because it put some part of the reading area mid-between the lamp and the eyes of the user.

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Isn't light from the side better,
as from the asymmetric lamp?

We often hear that light should fall from left when you are right-handed, and from right if you are left-handed. There is no contradiction when you use a freely adjustable lamp, but most people like to write on the side where their best hand is. It makes no sense to put your writing area to the left if you write with your right hand.

If you are right-handed and wish to have your work area to the right, you can place a freely adjustable lamp asymmetrically slightly to the left of your writing area. This is impossible with the asymmetric lamp.

From this position the lamp will not cause glare, and it can illuminate your work area well. If you choose to put the lamp in front of the computer screen, you will have to lift it so that it will not obstruct your view. Only with a lamp that is well protected against glare could this be done without inconvenience.

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What about rendering of shapes?

It is claimed that you see three-dimensional objects better if the light comes from the side, but although the statement is true, it is not relevant at the reading area of an office workplace. We are seldom interested in three-dimensional objects, but we look at a flat paper. Directional light is neither needed nor wanted. We want light to make the page legible with good contrast and without disturbing highlights or shadows.

Indirect light renders good contrast but no sense of depth.
Additional light may be needed, particularly with increasing age.

The asymmetric lamp,
when placed according to instructions, enhances recognition of shapes, but blots out the text with reflected glare.

The freely adjustable lamp can render excellent contrast but might not at the same time enhance sense of depth or recognition of shapes.

The three pictures above are all taken with the same camera settings.
In order to preserve true rendition as far as possible, no image manipulation was done.
The asymmetric lamp is positioned according to the manufacturer's manual.

Furthermore, in those situations where we do want directional lighting to accentuate the shape of objects, a freely adjustable lamp will accomplish this best. It gives you the freedom to choose any lighting angle you want.

Maybe, if a discussion on this theme arises, it is worthwhile to know that it is not a matter of how you direct the lamp, but how you orient the lamp relative to the object you are looking at. The direction of the light falling onto an object is governed by the positions of the object and the lamp, not any intrinsic property of the lamp.

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Scientific study confirms that a freely adjustable lamp is preferred

A recently performed study by Monica Säter at Ljushögskolan, not published yet, confirms that users prefer a glare protected freely adjustable lamp before an asymmetric desk lamp.

The study does not analyse why the glare-protected lamp is preferred, but it shows with statistically significant relevance, that users, given the option, prefer the freely adjustable lamp.

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