Holmarc's Apparatus Model HO-ED-LOE-02 is for the characterization of Optoelectronic components. Optoelectronics is the study and application of electronic devices that interacts with light. Optoelectronic devices are electrical to optical / optical to electrical transducers or instruments. These introductory - level experiments reveal the basic concepts of opto-electronics and are useful in courses dealing with applied physics, fiber optics, electronic devices, etc.