An apparatus for measuring moisture in an air sample, said apparatus comprising:
- a container for receiving a cryogen formed by a top wall, a bottom wall, a first side wall and a second side wall, wherein the top wall comprises a first opening to receive the cryogen into the container and a lid to seal the first opening, wherein the first side wall comprises a second opening positioned at a first proximal distance from the bottom wall;
- a pressure relief valve positioned on the lid sealing the first opening;
- an insulating sleeve inserted into the second opening of the container to form a third opening to receive the thermal conductive rod, wherein the insulating sleeve isolates the received thermal conductive rod from direct contact with the cryogen;
- a thermal conductive rod extending into the container through the third opening of the container, wherein a first diameter of a distal portion of the thermal conductive rod is larger than a second diameter of a proximal portion the of thermal conductive rod, wherein the first diameter of the distal portion of the thermal conductive rod is substantially same as a third diameter of the third opening formed by the insulating sleeve to allow a snug fit at an interface between the distal portion of the thermal conductive rod and the third opening formed by the insulating sleeve;
- a cold plate thermally coupled to the distal portion of the thermal conductive rod, wherein the cold plate comprises a first curved surface to receive the distal portion of the thermal conductive rod, wherein the cold plate thermally dissipates heat from the distal portion of the thermal conductive rod;
- a reflective element thermally coupled to the proximal portion of the thermal conductive rod, wherein the reflecting element comprises a reflective surface positioned to receive the air sample at a predetermined flow rate;
- a heating element positioned on the proximal portion of the thermal conductive rod at a second proximal distance from to the reflecting element and wrapped at least partially around the proximal portion of the thermal conductive rod, wherein the heating element selectively heats the reflective element;
- a temperature sensor positioned in thermal contact with the reflective element, wherein the temperature sensor generates a first signal when the reflective element reaches a frost point temperature;
- a mirror collar enclosing the proximal portion of the thermal conductive rod, the heating element and the temperature sensor;
- a light source positioned to illuminate the reflective surface of the reflecting element with a beam of light having a predetermined wavelength;
- a detector positioned to detect light reflected from the reflective surface of the reflecting element;
- an optics block for mounting the light source and detector, wherein the optics block is thermally coupled to the light source and the detector to maintain the light source and the detector at a predetermined temperature;
- a biconvex lens positioned to focus the light from the light source to illuminate the reflecting element and focus the light reflected by the reflective surface of the reflecting element to the detector;
- a lens heater thermally coupled to the biconvex lens, wherein the lens heater heats the biconvex lens to reduce condensate formed on the biconvex lens;
- a first intake tube comprising a fourth opening to receive the air sample and a fifth opening to deliver the air sample to flow across the reflective surface of the reflecting element;
- a second intake tube comprising a sixth opening to receive the air sample flowed across the reflective surface of the reflecting element and a seventh opening to discharge the air sample received via the sixth opening;
- a collar comprising:
- an eighth opening positioned to couple with the first intake tube and receive the air sample delivered from the fifth opening of the first intake tube;
- a ninth opening positioned to couple with the second intake tube and receive the air sample flowed across the reflective surface of the reflecting element;
- a tenth opening positioned to receive the reflecting element and the proximal portion of the thermal conductive rod enclosed by the mirror collar, wherein the receiving the proximal portion of the thermal conductive rod enclosed by the mirror collar and the reflecting element positions the reflecting element in a substantially center position inside the collar;
- an eleventh opening to receive the biconvex lens and position the biconvex lens to focus the light from the light source to the reflective surface of the reflecting element and focus the light reflected by the reflective surface of the reflecting element to the detector;
- and
- a processor electrically coupled to the heating element and the detector, wherein the processor receives electrical signals from the detector corresponding to the detected light reflected by the reflective surface of reflecting element, wherein the processor determines from the received electrical signals the moisture content in the air sample.