Longwave infrared imaging of a high-temperature, high-intensity light source

摘要

A neutral density (ND) filter made of an LWIR-transmissive, heat-resistant material is interposed between a longwave infrared (LWIR) imager and an entity that is highly emanative of both light and heat. According to exemplary inventive practice, the ND filter is a thermoplastic (e.g., polystyrene) sheet characterized by a thickness in the 1-2 mm range and a thermal conductivity≦0.13 W/m-K. Important parameters of the ND filter include LWIR transmittance (which depends on material and thickness) and thermal conductivity (which depends on material). The quality of the image taken of the entity is affected by the respective degrees of LWIR attenuation by, and heating up of, the ND filter. Accordingly, the material and the thickness of the ND filter are selected to optimize the image, in particular so as to avoid saturation and/or whiting-out of the image due to insufficient LWIR attenuation and/or excessive ND filter temperature.

主权项

1. An imaging method comprising:
providing an imager operable in the longwave infrared spectral region of electromagnetic radiation; providing a neutral density filter characterized by transmission of longwave infrared radiation and by resistance to heat; positioning said neutral density filter between said imager and an entity emanating electromagnetic radiation and heat;imaging said entity, said imaging including using said imager and said neutral density filter, wherein said neutral density filter attenuates longwave infrared radiation emanating from said entity, said neutral density filter resists heat emanating from said entity, and said imager receives longwave infrared radiation attenuated by said neutral density filter;
wherein said neutral density filter is made of a material having a thermal conductivity of greater than zero W/m-K and less than or equal to 0.13 W/m-K.