EmVision Grin Lensed Fiber-Optic Probe
Grin Lensed Probe Design.
The probe design is described in detail in US patent 8,432,542. An exploded view of the probe is shown in the following image.
The probe uses one low hydroxyl (OH) content 400-micron core, 0.22 NA collection fibers. A long-pass filter that rejects the laser light and passes the Raman light from the sample is positioned in between the front GRIN lens and the collection GRIN lens. The laser delivery fiber is a 100-micron core low OH, 0.22 NA fiber. A band-pass filter that rejects the silica raman and passes the laser light is positioned in between the front GRIN lens and the laser GRIN lens. The excitation light and collection light paths have separate paths through the lenses, but have the same focus. This configuration allows overlap of the excitation light and the collected light at the sample without interference from the GRIN lenses.
The probe uses epoxy to bond the required individual components together. The fibers, lenses and other components are placed inside a 2.4mm stainless steel needle tube.
Exploded View of the Raman Lensed Fiber-Optic Probe
The above image shows the exploded view of the probe distal tip illustrating the Raman laser excitation light and how the Raman collection light are directed to a complete overlap at a point in space near the front lens.
Zemax Software Ray Trace
Illustrated in red is the excitation light. The collected light is illustrated by the green rays. As can be seen from the tracing, the probe is designed to be an efficient collection probe. The probe can be designed for contact or have a small working distance from the probe tip.