Flow cell and concentration measuring device

A flow cell comprising:

• a body having a fluid passage and a light passage formed to pass through the fluid passage;
• an optical cable connected to the body to transmit source light from a spectrometer to the body and to transmit receiving light from the body to the spectrometer;
• a mirror lens body provided on both sides of the fluid passage to diffuse and condense light;
• a window provided on both sides of the fluid passage and inserted into the light passage to transmit light;
• and
• a lens bushing fixing each window to the body and connected to each mirror lens body,
• wherein a source light cable and a light receiving cable are arranged to be side by side with each other by being connected in a same direction with respect to the body, and
• wherein O-rings are provided to seal between the fluid passage and the light passage.