Beam, light refracted

A light beam is refracted to different extents by different compounds. This mechanism is used for refractive index detection. This detector is not sensitive and the selectivity differences are negligible for homologous compounds, but any solvent with a different refractive index to the analyte can be used as the eluent. This detector is mainly applied to size-exclusion and preparative-scale liquid chromatography. 

Refractive index (RI) detection is based on the principle that a light beam is refracted differently depending on the substance through which passes. A beam passing through a solu-... 

Figure 16.3 (a) Light refraction and reflection. Each interface reflects and refracts a portion of the incident beam, (h) Light refraction by a prism. 

With mobile phase in both cells the beams are refracted equally and light beams of equal energy fall on the dual element photodetector. With analyte in the sample cell the light beams are refracted to differing extents and different amounts of radiation fall on the photodetector. 

The incoming beam light is refracted by the linear material. At the interface with the NLO material the beam light will be refracted again and will leave the NLO material at the point A going toward the direction of channel 1 (CHI). 

---