Because the parts, early on, are so small, he thought that they could not be observed, even with his most powerful microscope.

It is impossible to see them without a very powerful microscope.

"My interest in your life would be undetectable even to the most powerful microscope."

Yeah he has but you need a very powerful microscope.

Then the whole picture appeared to leap at him as if suddenly brought into focus under a powerful microscope.

The abstract images seemed biological, like dark particles seen under a powerful microscope.

Frank was first to study the strand of hair under a powerful microscope.

Under powerful microscopes it was discovered that several pauses had been made in the signature of the later will.

The particles are not visible to the naked eye, and can only be seen under a very powerful microscope.

Laboratory facilities were still in place there, including a microscope more powerful than anything they had yet managed to build.