Creating a Near Perfect Flat Surface: Difficult but Possible

[sid_galt]

Is it possible to get a near perfect flat surface with the roughness no more than 1-10 nm at any point?

If it is, then how difficult is it?

 

[FredGarvin]

The surface of carbon face seals are extremely flat with incredibly smooth surface finishes. The flatness callouts I am used to seeing are .000035" or about three helium light bands. That is about the best I have ever seen. I think you'd be running into macroscopic troubles when talking about surfaces in terms of nanometers.

Here is a reference for you on the topic in regards to sealing surfaces and pumps:
http://www.mcnallyinstitute.com/Charts/flatness_readings.html

For those interested, The Mcnally Institute website has some fantastic information regarding pumps and seals. It is a very valuable resource!

 

[Gokul43201]

We routinely make samples that have a flatness and parallelism of less than 100nm over an area of about 10 sq. mm. The polishing process is both tricky and painful (in addition to being material specific), and getting a better flatness would require a substantially greater monetary investment.

What material are you working with, and what is the size of the active area that you want flat ? And what's your budget ?

 

[sid_galt]

What material are you working with, and what is the size of the active area that you want flat ? And what's your budget ?

I am not working on any material. I was just curious.

 

[FredGarvin]

We routinely make samples that have a flatness and parallelism of less than 100nm over an area of about 10 sq. mm.

What componds do you polish with? Is this by hand? What is the purpose of the flatness/finish tolerance being so darned low (applications)?

 

[Gokul43201]

The polishing is done in several stages, mostly by hand, with the assistance of a polishing jig. The polishing compound is very specific to the material that we are polishing - Gallium Arsenide. Why do we need this low a tolerance ? Because we measure quantum transport phenomena in GaAs quantum well structures where the well spacing in just few tens of nanometers. This is fundamental research and has no applications as of now.