Thomas RECORDING offers a combination of a 4 core quartz glass insulated platinumtungsten tetrode fiber (OD=100μm) and an optical fiber (OD=120μm) in a parallel arrangement like shown in figure 1.

Figure 1 Thomas Optetrode consisting of a Thomas tetrode and a Thomas optical fiber.
The Thomas Optetrode combines the outstanding recording performance of Thomas tetrodes with the globular light distribution of Thomas optical fibers.
Mechler et al. reported recently, that tetrodes of nonplanar contact configuration (such as the conical Thomas tetrodes), unlike some other single-cell recording probes (e.g., linear or some planar arrays), have full spherical sensitivity and thus offer spatially unconstrained data [for detaisl see 1, 2]. The Thomas optical fiber offers a globular light distribution which is optimal for the activation of light sensitive neurons in the recording sphere of the Thomas tetrode.   
The Thomas Optetrode can be adapted to the special requirements of our customers. Details are shown in the optetrode product brochure below. If you should have any further question please do not hesitate to contact us!