A light illuminating element, comprising:
- a transparent closed casing, said casing having a first inner side, a second inner side, a first outer side and a second outer side or a first inner side, a second inner side, a first outer side, a second outer side and at least one transparent partition plate, the first outer side corresponding to the first inner side, and the second outer side corresponding to the second inner side;
- an exciting illuminating gas, disposed over said transparent closed casing, and suitable for providing an ultraviolet light with at least one specific wavelength;
- an exciting coating, disposed over said first inner side or over the transparent partition plate provided on said first inner side or over said second inner side or over the transparent partition plate provided on said second inner side, or over said first inner side or over the transparent partition plate provided on said first inner side and over said second inner side or over the transparent partition plate provided on said second inner side, or over the transparent partition plate within said transparent closed casing, said exciting coating suitable for absorbing said ultraviolet light with at least one of the specific wavelength to provide a visible light;
- and
- a dielectric multi-layer long-pass filter, disposed over said first inner side or over the transparent partition plate provided on said first inner side or over said second inner side or over the transparent partition plate provided on said second inner side, or over said first inner side or over the transparent partition plate provided on said first inner side and over said second inner side or over the transparent partition plate provided on said second inner side, or over said first outer side or said second outer side, or over said first outer side and said second outer side, or over the transparent partition plate within said transparent closed casing on one or two sides, said dielectric multi-layer long-pass filter suitable for reflecting said ultraviolet light with at least one of the specific wavelength and allowing the visible light to pass through,
- wherein the reflecting angle of said ultraviolet light with at least one of the specific wavelength has a wide angle of incidence, and a range of the reflecting angle of said ultraviolet light with at least one of the specific wavelength is between 0 and 90 degrees, with 0 and 90 degrees included, and
- wherein said exciting coating is closer to said exciting illuminating gas than said dielectric multi-layer long-pass filter.