Dear Dileep Karnam ,

it is not really clear to me what are you doing and aiming at.

But filling of your bore hole with wax might be a solution. So the hole cannot be filled with the polishing agent.

Wax can be removed later on...

Best regards

G.M.

Why don't you cut a cross-section?

If you don't have precise enough tools you can just cut you sample near and polish till you enter the desired plane.

Dear Gerhard Martens ,

Thank you for the suggestion. I want to see the cross section profile of the drilled hole and the hole depth. Every time it ended up with either too much of polishing or very less polishing. Just want to know how others are doing it.

Hello Dmitry Nuzhdin ,

This could also be a good solution. Thanks a lot.

Thanks Dileep Karnam ,

for feed back.

The wax 'solution' will bring the cross section information; but unfortunately the information about the residual depth is'nt available on the fly (without removing the wax).

There might be some type of material available (e.g. some wax) which will evaporate a low temperatures;

so that the removement can be done by heating...

Best regards

G.M.

Appreciate your help Gerhard Martens

Perhaps you may look into lensless holographic imaging that may allow you to focus at any depth via software processing e.g. https://www.photonics.com/Articles/Lens-Free_Microscopy_Focuses_on_Commercialization/a65007

Dear Nikolay Pavlov ,

This is quite interesting. Thanks for sharing.

Have you considered using high-resolution X-Ray-tomography? It is reported to deliver resolutions down to 1 micrometer

(see e.g. https://mlz-garching.de/x-ray-tomography/de)

Plus: It is non-destructive.

With best regards

G. T.