OPTICAL DIELECTRIC HUMIDITY SENSOR

THE INNOVATIVE ASPECT OF THIS PROPOSAL IS THE MEASUREMENT OF ATMOSPHERIC MOISTURE THROUGH ITS EFFECT ON THE TRANSMISSION OF LIGHT THROUGH A MULTILAYER DIELECTRIC MIRROR. THIS EFFECT HAS NOT BEEN EXPLOITED IN THE PAST, BECAUSE IT IS UNDERSIRABLE IN THE NORMAL USE OF DIELECTRIC MIRRORS. IN SPITE OF THE FACT THAT MIRRORS ARE NORMALLY DESIGNED TO MINIMIZE THEIR SENSITIVITY TO HUMIDITY, RECENT OBSERVATIONS INDICATE THAT THEY CAN BE QUITE SENSITIVE. TO DETERMINE WHEHTER A HYGROMETER BASED ON THIS EFFECT IS FEASIBLE, WE WILL MEASURE THE TRANSMISSION OF COMMERCIALLY AVAILABLE DIELECTRIC MIRRORS FOR A WIDE RANGE OF TEMPERATURE AND RELATIVE HUMIDITY. WE WILL DETERMINE THE DYNAMIC RESPONSE OF THE MIRRORS BY MEASURING THE TRANSMISSION FOR TIME-VARYING RELATIVE HUMIDTY AND DETERMINE WHETHER THE EFFECT IS REPRODUCIBLE. WE WILL PERFORM A TEST ON POROUS THIN FILMS TO VERIFY THAT THE PHENOMENON RESPONSIBLE FOR THE SENSITIVITY TO MOSITURE IS ADSORPTION OF WATER IN THE POROUS LAYERS OF THE DIELECTRIC MIRRORS. THIS TEST WILL ALSO INDICATE HOW THE SENSITIVITY CAN BE ENHANCES.