This proposal is aimed at the ultimate development of a high accuracy, miniature probe capable of inspecting manufactured parts with complex geometries. A novel laser based, non-contact inspection technique will be employed and the device is called a non-contact pencil probe because of its planned shape and size. The optical system is divided into two subsystems; these are illumination and viewing subsystems. A triangulation method will be used. Conventional optical components are not well suited for the pencil probe because of their large relative size. Radically different optical techniques are required to reach the proposed goals. The use of graded index (GRIN) lenses is planned. The GRIN lenses behave optically like conventional lenses but have constant thickness with varied index of refraction instead of the conventional constant index of refraction with varied thickness. GRIN lenses can be obtained in small diameter sizes. The illumination and viewing optics of the proposed device will consist of long narrow GRIN rod lenses. A laser diode will be used as the illumination source and a detector array or a lateral effect photodiode as the detector. The Phase I research plan is to design and build a prototype device and experimentally demonstrate the feasibility of the non-contact pencil probe. A Phase II is planned which will modify and optimize the pencil probe to meet the largest number of inspection needs. If this research is successful, Phase III will obtain funding to commercialize this device. The pencil probe should increase inspection capabilities and lead to improved quality. Application would be to inspection of complex geometries, such as profiling turbine blades, detailing piston ring grooves, viewing parts hidden from external view, and looking at threads within a hole.
