A system for coupling a Raman probe head to a port in a bioreactor vessel containing a reaction medium, the system comprising: a Raman analyzer; a barb component with a distal end including an integral window with proximal and distal surfaces, the barb component being physically configured to be received by a port into a bioreactor vessel such that the distal surface of the window is exposed to a reaction medium in the vessel; an optic component configured to be received by the barb component, the optic component including a proximal end adapted for coupling to a Raman probe head characterized in that : the optic component further includes a distal end including at least one lens for focusing light to, and collecting light from, a sample focus in the reaction medium for analysis by a Raman analyzer coupled to the probe head; wherein the sample focus of the lens in the reaction medium is set at a predetermined distance from the distal surface of the window using a spacer component that is adjusted and aligned using a focus alignment tool; wherein the lens is retained within a lens mount axially moveable within the optic component; wherein the spacer component includes proximal and distal ends and, once the predetermined distance is established using the focus alignment tool, the proximal end of the spacer component is bonded to the lens mount with the distal end of the spacer adapted for contact with the proximal surface of the window; and further including a spring in the optic component for biasing the lens mount distally to ensure that the distal end of the spacer component maintains contact with the proximal surface of the window. a Raman analyzer; a barb component with a distal end including an integral window with proximal and distal surfaces, the barb component being physically configured to be received by a port into a bioreactor vessel such that the distal surface of the window is exposed to a reaction medium in the vessel; an optic component configured to be received by the barb component, the optic component including a proximal end adapted for coupling to a Raman probe head characterized in that : the optic component further includes a distal end including at least one lens for focusing light to, and collecting light from, a sample focus in the reaction medium for analysis by a Raman analyzer coupled to the probe head; wherein the sample focus of the lens in the reaction medium is set at a predetermined distance from the distal surface of the window using a spacer component that is adjusted and aligned using a focus alignment tool; wherein the lens is retained within a lens mount axially moveable within the optic component; wherein the spacer component includes proximal and distal ends and, once the predetermined distance is established using the focus alignment tool, the proximal end of the spacer component is bonded to the lens mount with the distal end of the spacer adapted for contact with the proximal surface of the window; and further including a spring in the optic component for biasing the lens mount distally to ensure that the distal end of the spacer component maintains contact with the proximal surface of the window. <EOS>