| 摘要 |
An optically-based overfill detection probe is provided that has a prism with a substantially quadrilateral cross-sectional shape, such that internal reflection angles are less than ninety degrees. The prism is made of a fluoropolymer, preferably Teflon.RTM. PFA, and uses an infrared optical signal. The prism material has a high resistance to chemical solvents, has high signal transmission in the infrared (IR) wavelength range, is less prone to condensation and frost than plastic or glass, and enables the production of prisms at significantly less cost than glass. The substantially quadrilateral cross-sectional shape of the prism, in itself, has the advantage of allowing angles of incidence much less than ninety degrees on internal prism surfaces, thus reducing signal loss from surface irregularities. The probe also includes a two-piece housing structure that compresses an outwardly-extending portion of the prism material to firmly hold the prism in place, and force the material into sealing contact with an inner surface of the housing. The housing has an elongate portion which encompasses the prism, and which extends toward the fluid, preventing any light which escapes the prism from being externally reflected back to the photodetector of the probe.
|
