Research On High-performance Cold LED Light Source For Medical Endoscope

Medical electronic endoscopes have become widely used medical equipment. Doctors can not only observe the structures of internal organs and diagnose lesions, but also can make images displayed and stored. Due to the body’s internal a dark environment, electronic endoscope imaging requires in vitro lighting source for auxiliary lighting. The illumination light through the optical fiber bundle into the body. The image quality is closely related with the illumination light color rendering, color temperature and the luminance. Current endoscope light source is a gas discharge light source, such as a xenon lamp. Although its output luminous flux is high, color rendering quality is good, but it’s contain the problems of a large amount of heat, short life, high energy consumption. LED light source takes the advantages of low energy consumption, long life and other advantages. The output luminous flux and color of the LED light source are also gradually improving as technology advances.This paper aims to study the medical use of LED as a light-emitting element, with high-performance white light source, to meet the requirements of the electronic endoscope for color rendering, color temperature and the luminance flux output. The study includes the selection of the LED chip, opto-mechanical system design, and control circuit design, the experimental system to build and test. Based on performance requirements, this paper proposed two methods to make white LED:RGB three-color mixed to generate white light, high color temperature cool white plus red mixed to generate low color warm white. Theoretical calculating the different characteristics of the two programs, simulating the effect and test the actual result. The main work includes the following aspects:(1) Use OSRAM OSTAR SMT LE A/T/B/UW S2W LED chip solution. It takes the advantages of high power and large luminous flux output. Universal application of the optical characteristics of the plastic aspheric collimating lens group was designed to improve the collimated efficiency.(2) Applying a multiplexed optical mixing dichroic mirror to the optical element of the single-channel optical. And based on the two dichroic mirrors consisting of X-cube beam combiner mirror. Design versatility light mixing system structure. Two experimental programs can both use in the same system.(3) Starting from the definition of the color rendering index, based on the emission spectrum of the LED light source, calculate the ratio of the light flux of the two solutions in each to achieve maximum color rendering index, and simulate the result. After experimental system structured, taking the actual quality test.The research design of medical endoscope white LED lighting systems reached the international advanced level, has a practical application value. Application of cold white plus red mixed generate high CRI warm white, the general color rendering index Ra can reach93.9, with same time output luminous flux can reached hundreds of lumens. Medical light source at the same time meet the needs of high-color reduction and large luminous flux.