- Joined
- Jan 15, 2015
- Messages
- 446
I was able to use oil immersion w/metallographic microscope for 1000x images, even able to angle the edge. Images at 400x not good enough to make out apex features but using depth of field one could estimate degree of bevel convexity and scratch depth. Plus the software allows for a range of various contrast enhancements.
And for a fact, stylus profilometers were used for sheer cutters and some forms of burst cut dies. You can't use them with most thin blades, but as the angle becomes less acute yes.
Spatial distortion is definitely an issue w/SEMs, better for studying morphology than assigning absolute measurement values, although methods of compensating are now pretty effective.
I'm not sure why I'm wasting my time here, but
I've seen your optical images.
I have two stylus profilometers, a Dektak I bought used about 20 years ago and a KLA Tencor P-7 that I bought new a few years ago. The resolution of these depends on the tip radius, which is typically 2-5 microns. The sell sharper tips, but they are a few thousand each - I have sharpened some myself with FIB and it is possible to reach 0.5 micron resolution, but the tip angle is very high and there is absolutely no way to scan the apex of a blade with one. The scanning probes that can achieve "better resolution than optical" are AFM (atomic force microscopes) and those tips are extraordinarily fragile and can ONLY be used on flat surfaces.
I don't know where you get your information about SEM, but it is just wrong. Any SEM built in the past 30+ years has a calibration routine done by the install technician that will provide better than 3% accuracy over the full range of conditions. When required for ISO9001, I check with my NIST calibrated MRS-3 standard and it's never been off by more than 1%.