Xradia, a Concord, Calif company that sells high resolution 3D x-ray microscopes and fluorescence imaging systems for the semiconductor and biology industries, has raised $4 million.

Lead investor in this fourth round of funding was Harris & Harris Group.

Harris & Harris Group has so far focused its investments in “tiny technology, including nanotechnology, microsystems and microelectromechanical systems (MEMS).”

Here is the company’s announcement.

Previously, Xradia raised about $5 million in angel funding and about $5 million from grant funding including the National Institutes of Health, according to VentureWire (sub required).