MA Sala Patents in More Detail

Measuring Inclusion Depth

A rather boring title, but the story behind is really cool.

192 LASERs are used to generate the energy of a typical star (like our sun Sol) and converge this energy on a tiny target.


The target chamber, at the upper left, is 5mm across and 9mm high and is made from gold or uranium. More Information

NIF X-ray View


NIF User's Guide (PDF)


The LASER array from above looks like:


Within this array are thousands of optics for forming the light. At the beginning, the LASER beam is 18" X 18" square!

These optics are made from a type of glass called High Purity Fused Silica (HPFS) and CORNING Inc. provided whilst I worked there as a Sr. Research Scientist. The lens-blanks need to be absolutely free from distortion, imperfections and inclusions >1µ; if the optic contained any of these, they would explode when illuminated by the LASER!

I was assigned to lead the team that would develop the tools that would ensure the delivery of absolutely pure glass.


An optic under inspection at NIF after our instruments declared it to be "defect-free."


The HPFS is mined from a boule of HPFS measuring approximately 6' across and 6" to 8" thick. A perfect boule was not possible, so areas within the boule are located with the desired characteristics.


Before our contribution, technicians working in a large dark-room (walls/ ceilings blackened and no lights) would peer into the boule using a shop trouble-light. Moving the light this-way-and-that, ever-changing the sight-line angle, inclusions would reveal themselves as tiny lights buried within the glass. The time this consumed was mind-boggling, not to mention the possibilities for errors in spotting.

We developed the LASER Scanning Interferometer completely automating the process, returning maps and charts as to where every inclusion lay.


In a process that initially took days to accomplish manually and an error-rate that was pissing-off NIF, our process took hours to return detailed maps and charts so Technicians knew exactly where to mine the glass.


The smaller cylinders are the areas where glass was to be mined containing minimal inclusions.

Star Trek