Abstract: A transverse optical transmission probe having a probe body and a probe tip. The probe use optical fibers to both transmit radiation from an instrument to the probe tip and to return the sample affected radiation to the instrument. The fibers are in parallel and contained in the probe body. The probe tip includes two optical elements that protrude into the sample and are configured to define a sample gap so that incident radiation pass through the sample in a direction transverse to the axis to the probe and eventually reaches the receiving fiber. Each of the optical elements may be formed from a single piece of material or may be a composite formed by adhering two or more pieces of material together. One or more lensed surfaces may be used to cause the end of the transmitting fiber to be imaged on the end of the receiving fiber.

Abstract: A spectroscopic measuring device for minimizing spurious absorption due to undesired gases. The device includes a probe body, or a transmission cell formed from a central measurement cell and first and second probe bodies. Each probe body is subject to leakage of undesired gas, especially over time in the presence of high pressure gas. Each probe body includes a bore located between a primary window disposed at or near a distal end and a secondary window located at or near the proximal end. It being observed that the absorbance is proportional to the pathlength and inversely proportional to the volume as long as the pressure in the probe body remains low compared to that in the measurement cell, a glass filler rod is located in the bore and a is void located adjacent to the filler glass rod, thereby minimizing spurious absorption even in the presence of leakage.