The history of shadowless lamps

The world's earliest surgical shadowless lamp was invented by French professor Wei Lan in Britain in the 1920s. Welland placed a 100 watt bulb in the center of a refractive lens formed by many narrow flat mirrors evenly placed on the dome of the shadowless lamp, so the whole shadowless lamp was conical and the spire was removed.

The second reform of shadowless lamps is the single-lamp shadowless lamps in France and the track shadowless lamps in the 1930s and 1940s in the United States. At that time, incandescent bulbs were used as light sources, and the maximum power of bulbs could only reach 200 watts. The filament winding area is very large, so it is difficult to control the light path and focus. The reflector is polished by copper, so it is not easy to reflect light, so the illumination of shadowless lamp is extremely low.

In 1950s, in order to improve the illumination of shadowless lamps, Europe and Japan produced and used perforated multi-lamp shadowless lamps. This type of shadowless lamp increases the number of light sources, and uses high-purity aluminum as a small reflector to improve the illumination of the shadowless lamp.

However, due to the increase of the number of light bulbs, the temperature of this shadowless lamp rises rapidly, which is easy to cause discomfort to doctors and dryness of surgical tissues, which is not conducive to the postoperative rehabilitation of patients.

In the early 1980 s, the daily newspaper began to produce cold light hole surgery shadowless lamps with halogen light sources. In the late 1980s and early 1990s, shadowless lamps for total reflection surgery came out. This kind of shadowless lamp uses computer-aided design technology to design the curved surface of the reflector, and the curved surface is formed by industrial stamping at one time to form a polygonal reflector. The light source of this shadowless lamp is not only as bright as sunlight, but also has no shadow.

Extended data:

Shadowless lamp principle

In fact, a shadowless lamp can't be a shadowless lamp. It just brightens the umbra and makes it inconspicuous. Shadows are formed when light shines on objects. Shadows are different in every part of the earth. If you carefully observe the shadow under the electric light, you will also find that the middle part of the shadow is particularly dark and the periphery is slightly shallow.

The particularly dark part in the middle of the shadow is called umbra, and the dark part around it is called penumbra. These phenomena are closely related to the linear propagation of light. If you put a cylindrical tea cone on the table and light a candle next to it, it will cast a clear shadow.

If two candles are lit next to the tea cone, two overlapping shadows will be formed. The overlapping part of the two shadows is completely black without light, which is the umbra; Next to the umbra, where only candles can shine, is the penumbra that is half bright and half dark. If three or even four candles are lit, the umbra will gradually shrink and many layers will appear in the penumbra.

The same is true for objects that can produce shadows composed of umbra and penumbra under electric lights. Obviously, the larger the area of the luminous object, the smaller the umbra. If we light a circle of candles around the tea cone, the umbra will disappear completely, and the penumbra will be too bright to see. According to the above principle, scientists have made a shadowless lamp for surgery.

It arranges lamps with high luminous intensity in a circle on the lamp board to synthesize a large-area light source. In this way, the light can shine on the operating table from different angles, which not only ensures the sufficient brightness of the surgical field of vision, but also does not produce obvious shadows, so it is called shadowless lamp.

Baidu encyclopedia-shadowless lamp