We suggest to measure the Pomeron phase and discover odderon via the measurement of charge asymmetry of pions in the diffractive processes ep\to e\pi ⁺\pi ^- p, eA\to e\pi ⁺\pi ^- A and in the processes AA\to AA\pi ⁺\pi ^- with two rapidity gaps.

PACS numbers: 11.30.Er, 13.60.Le, 25.75.--q