Blood counting machines aspirate a very small amount of the specimen through narrow tubing followed by an aperture and a laser flow cell. Laser eye sensors count the number of cells passing through the aperature, and can identify them; this is flow cytometry.
In computing, Extract, Transform and Load (ETL) refers to a process in database usage and especially in data warehousing that performs: Data extraction â extracts data from homogeneous or heterogeneous data sources.
ETL tools are used for data integration projects, data warehousing and so on. If you ever heard about Microsoft SSIS tool shipped with MS SQL Server - that should give you an idea what ODI is for. This is a good white paper that explains how to use ODI and what the benefits are versus the custom coding.