SIGMAKOKI Cold Filter

Tungsten lamps and halogen lamps emit heat rays (infrared rays) along with visible light, which can raise the temperature of the irradiated object. Cold filters prevent the temperature of the irradiated object from rising by transmitting visible light and attenuating infrared light. By combining the rapid attenuation of transmittance from visible to near infrared, which is a characteristic of dielectric multilayer mirrors, and the high absorption rate of the long infrared wavelength side (1000 to 2000 nm), which is a characteristic of heat ray absorbing filters, it is possible to transmit the entire visible light range and efficiently block infrared light. It can also be used as a powerful infrared cut filter for CCD cameras. By attaching this filter, infrared light can be prevented from being reflected in the image. It can also be used when you do not want to change the temperature of the specimen due to lighting, such as with a microscope for biological observation. *If there is light that is incident at an oblique angle on the filter, the transmittance will decrease on the long wavelength side of the visible range. *If a filter is placed near a light source such as a lamp, a rapid temperature change will occur due to infrared absorption, which may damage the filter. *The back of the cold filter does not have an anti-reflection coating in the visible range. *As a result, there is a loss of less than 20% due to absorption by the heat absorbing filter and backside reflection (4%).