Optical flow cell for an optical measuring device

An optical flow cell for a measuring device, the optical flow cell comprising:

• a holder configured to be removably mounted across a flow channel through a mounting site hole of the measuring device;
• an input light guide including a light exit surface;
• and
• an output light guide including a light entrance surface,
• said input light guide and output light guide being supported by the holder, wherein the holder extends along a first axis configured to be transverse to the flow channel and has a through hole for receiving a flow of a sample fluid, said through hole being substantially transverse to said first axis,
• wherein the input light guide and output light guide further are arranged in said holder so that the light exit surface and the light entrance surface protrude from the holder and extend into said through hole and are arranged to be in optical alignment with each other along the first axis and at a first distance from each other, and
• wherein the holder comprises a material with a thermal expansion of less than 20×10−6 m/mK.