MODEL RELEASED. Blood testing. Medical laboratory worker placing samples in an analytical machine. This machine is an absorbance reader, which uses spectrometry to analyse blood samples by shining light through them. This can detect bacterial growth, as well as the proportions of components of the blood. The absorbance reader is at left, with an incubator to its right. The blood samples are contained in microplates, equipment designed for use in highly automated machines like this one.