![]() The far-UVC light source may include an excimer lamp. The wavelength selective mirror may be concave, flat or convex. A light diffusion board may be arranged to receive the far-UVC light from the wavelength selective mirror, or if there is a sequence of mirrors, from the sequence of mirrors, and to distribute the light to form an output of the far-UVC optical system. The blocking member may be a further mirror arranged to reflect light from the far-UVC light source to the wavelength selective mirror, or if there is a sequence of mirrors, the first mirror of the sequence. A blocking member may be arranged to block light from the far-UVC light source that would, if not blocked, avoid the wavelength selective mirror, or if there is a sequence of mirrors, the first mirror of the sequence. The wavelength selective mirror may be one of plural wavelength selective mirrors in the sequence of mirrors. The far-UVC optical system may have plural mirrors arranged in a sequence where each successive mirror of the sequence receives light reflected from a corresponding previous mirror of the sequence, the wavelength selective mirror being a mirror of the plural mirrors arranged in the sequence. The wavelength selective coating may include one or more dielectric layers of thickness and refractive index selected to reflect the at least one wavelength. The base surface may be a reflective surface. The wavelength selective coating may include a chemical that absorbs the at least another wavelength and does not substantially absorb the at least one wavelength. In various embodiments, there may be included any one or more of the following features: the wavelength selective mirror may have a wavelength selective coating over a base surface of the wavelength selective mirror. The far-UVC optical system includes a far-UVC light source and a wavelength selective mirror arranged to receive far-UVC light from the far-UVC light source and to disproportionately reflect the far-UVC light in at least one wavelength of the far-UVC light relative to at least another wavelength of light emitted by the far-UVC light source. There is provided a far-UVC optical system for a germicidal lighting system. Hence the amount of far UVC radiation on one person per 24-hour cycle has a limit in this standard. In this standard, there is no consideration of the human safety characteristics of the far-UVC radiation around 222 nm. IEC 62471:2006 is a photobiological safety standard for all types of lamps. For example, the range of 200 nm to 230 nm may be suitable. The term “far-UVC” is used in this document to refer to 207 nm, 222 nm, and the full contiguous range of wavelengths, including 207 and 222 nm and extending to shorter wavelengths than 207 nm, longer wavelengths than 222 nm, and intermediate wavelengths, that is germicidally effective while being substantially nonharmful to humans. Studies have focused on these specific excimer lamp wavelengths, but the reasons for their non-harmfulness to humans and effectiveness on bacteria and viruses can be expected to apply to a range of wavelengths that will extend some distance shorter than 207 nm, longer than 222 nm, and everything in between. Each excimer lamp may produce a range of wavelengths, and studies have used filters to exclude light beyond, e.g., a nanometer or so from the respective peaks, or outside a range believed to be non-harmful to humans. These are peak wavelengths provided by these excimer lamps. Examples of wavelengths within this range include 207 nm, as produced by a Kr-Br excimer lamp, and 222 nm, as produced by a Kr-Cl excimer lamp. However, it can still penetrate bacteria and viruses which are much smaller than human cells. This range, referred to in this document as “far-UVC”, has a smaller distance of penetration through biological material and in particular cannot penetrate either the human stratum corneum (the outer dead-cell skin layer), nor the ocular tear layer, nor even the cytoplasm of individual human cells. A range of wavelengths have been found to be much less damaging to humans and animals. However, many wavelengths of UVC including 254 nm cause radiation damage to the skin of human and animals. For example, 254 nm UVC light from mercury lamps has been commonly used. UVC light is used as a disinfection tool.
0 Comments
Leave a Reply. |