| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve a problem of a conventional infrared ray bulb that red light escapes from the bulb as the cut-off wavelength is shifted to the short wavelength side relative to the light diagonally passing through an infrared ray transmitting filter, which is against a related regulation. SOLUTION: The infrared ray bulb 1 has the infrared ray transmitting filter 5 consisting of a plurality of layered optical films 5a whose thickness is set as the center wavelength (nd)>=620 nm. The distribution of thickness of the optical films relative to the transmitting angleθ, with the thickness when infrared rays from a light emission source 2a orthogonally cross and pass through the infrared ray transmitting filter 5 as the standard, complies with the expression: optical film parameter (θ)=1×10<-5>θ<2> +0.0021+0.9984. The lighting instrument 10 for infrared ray projection has the infrared ray bulb 1 as the light source. Red light shall never be projected from the lighting instrument for infrared ray projection in any state of lighting.</p> |
