Why is there no shadow under the shadowless lamp?

Surgical shadowless lamp is used to illuminate the surgical site, so as to best observe small and low-contrast objects with different depths in incision and body control. Because the operator's head, hands and instruments may cause interference shadows at the surgical site, the design of surgical shadowless lamp should eliminate shadows as much as possible and minimize color distortion. In addition, the shadowless lamp must be able to work continuously for a long time without emitting too much heat, because overheating will make the operator uncomfortable and dry the tissue in the operation area.

The surgical shadowless lamp generally consists of one or more lamp holders, which are fixed on the cantilever and can move vertically or circularly. The cantilever is usually connected to the fixed connector and can rotate around it. The shadowless lamp adopts sterilization handle or sterilization hoop (curved rail) for flexible positioning, and has the function of automatic braking and stopping to control its positioning, so as to keep proper space above and around the operation site. The fixing device of the shadowless lamp can be placed on the fixed point of the ceiling or wall, or on the track of the ceiling.

For shadowless lamps installed on the ceiling, a transformer of 1 or above should be installed in the remote control box on the ceiling or wall to convert the input power supply voltage into the low voltage required by most bulbs. Most shadowless lamps have dimming controllers, and some products can also adjust the light field range to reduce the light around the operation site (reflections and flashes from sheets, gauze or instruments will make eyes uncomfortable).

Why is the shadowless lamp called "shadowless lamp"?

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.