an optical probe for measuring light signals includes a first optical fiber guiding incoming light , a lens focusing incoming light towards a sample and collecting altered light from the sample , a second optical fiber guiding altered light , a light logging device measuring intensity fluctuations in the incoming light , wherein the light logging device is positioned after the first optical fiber , whereby the light logging device receives a part of the incoming light from the first fiber . the optical probe is normally applied for measuring light signals in vivo , and finds its primary applications within the field of optical spectroscopic measurements , where the light signals measured by the probe are applied in combination with an apparatus wherein light signals are analyzed against its spectral components for instance in raman , fluorescence , phosphorescence absorption , diffusion and transmission studies .