Halogen lamps have given way to xenon lamps as illuminants for medical endoscopes. However, xenon lamps' short lifespan and complicated lamp replacement make them uneconomical in use. With the goal of longer lamp lifespan and greater energy efficiency, illuminants composed of LEDs and LDs with high luminous efficiency, or illuminants that combine blue LDs with a wavelength conversion element (green to red), are finding wider use.

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In illuminants composed of LEDs, a limit exists in the amount of emitted light that can be transmitted to fibers, resulting in an amount of light that is insufficient compared to conventional xenon lamp illuminants. Constructing illuminants using only LDs requires arranging different wavelengths of visible light (400 to 700 nm) in succession. However, preparing LDs of the required types results in a very high cost, making this source of light uneconomical.

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The combination of blue LDs and a wavelength conversion element is most widely used to construct light sources with superior economy. As with LED illuminants, however, the amount of light sent to the fibers can be considered insufficient. In addition, limitations of the wavelength conversion element result in insufficient red color, reducing the capabilities of the endoscope.

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In response, our company is able to provide irradiation that ranges from green to red or even infrared light by transmission of ample blue LD light to the fiber tips and by utilization of a wavelength conversion element made using our high-transparency quantum dot materials. Moreover, the excitation light source generally requires only one type of blue LD, enabling economically outstanding illuminants.