Optical filter
Color tmeperature conversion filters are used to balance the color temperature of a light source. They will balance tungsten light source to daylight or vice versa, providing significant changes in color temperature. These filters can also be used to create an intertional warm or cool effect.
Optical low pass filter (OLPF) is used in high end (high resolution) digital camera sensor to eliminate interference influence (Moire pattern) by crystalline birefringency. An OLPF can cut off the undesired high spatial frequency when the sensor resulting the image. IR cut-off function is often incorporated into OLPF as well. Some use absorptive blue glass + AR , or direct coating an IR cut thin films layers .
The ir pass filter (infrared pass filters) that operates over a very wide temperature range to reflect the entire visible light spectrum while very efficiently transmitting infrared wavelengths. So that can increase the temperature of bathroom.
Conversion color temperature filters
