OT光 - 也称为operating lightor手术灯头– is a医疗装置打算在surgical procedure通过照亮本地或腔patient。几个手术灯的组合通常称为“外科光系统”。

In the mid-1850s,手术室被朝东南建造，窗户位于天花板上，以尽可能从自然的阳光中受益。最大的问题是照明的依赖性以及是否a程序could be done on the time of day and weather conditions. Furthermore, a doctor, nurse or medical equipment easily blocked the light. The use of mirrors on the four corners of the ceiling to reflect sunlight towards the operating table only slightly alleviated these problems.

尝试使用光学冷凝器in an indirect light to reduce the加热，但没有成功。入口电灯1880年代进入手术室，伴随着问题。随着早期的电气技术控制，发射的光很差。电灯仍在移动和扩散，很棒热辐射。

发光二极管随着光源消除热辐射问题并减少能量需求。

The distance between the points of 20% illumination intensity above and below the center point. From the point of maximum illumination, which is the center of the light field 1 meter from the light-emitting surface, the photometer is moved toward the light until the light intensity measured falls to 20% of the maximum value. The distance between the center and this point is defined as L1. The similarly measured distance in the direction away from the light is L2. The depth of illumination without needing to refocus is the sum of the two distances L1 and L2. In the second edition of the IEC standard, published in 2009, the threshold value was revised from 20% to 60%