Refocusing wavelengths to a common focal plane for electrical trace testing

摘要

The present invention relates to a method and apparatus for testing electrical traces wherein ultraviolet wavelengths from a laser source and visible wavelengths from a scanning camera are focused to a common focal plane. In a first embodiment of the method and apparatus, the wavelengths are commonly focused using an auxiliary lens having a power sufficient to accommodate the difference between the focusing plane of the ultraviolet laser source and the scanning camera. In a second embodiment, the wavelengths are commonly focused by moving the camera optics of the scanning camera relative to its visible light source. Both of these methods and apparatuses employ a fused silica lens system, avoiding the use of calcium fluoride.