Efficient phase defect detection system and method

An optical inspection method for inspecting a transparent substrate having a surface and detecting optical variations therein, said method comprising:

• providing at least one illumination beam along an illumination path, where said at least one illumination beam has an associated area on the surface of the substrate;
• and
• producing substantially simultaneously at least two signals containing different phase information in response to said at least one illumination beam interacting with said substrate;
• and
• determining said variations in the phase or amplitude of modified illumination beams at associated surface area according to said signals.

An optical inspection apparatus for inspecting an article having a front surface and detecting optical variations therein, said apparatus comprising:

• an optical system comprising
• an illumination system providing at least one illumination beam along an illumination path, where each illumination beam has an associated area on the front surface of the article;
• a collection system producing at least two signals containing different phase information in response to said at least one illumination beam after modification by said article;
• and
• an analyzer determining said variations in the phase or amplitude of modified illumination beams at associated front surface area(s) according to said signals,
• wherein said illumination system or collection system comprises a Zernike plate with orthogonally polarized, complementary +/−α degree Zernike point spread functions, where α is between the values of 0 and 180 degrees.

An optical inspection method for inspecting an article having a front surface and detecting optical variations therein, said method comprising:

• providing at least one illumination beam along an illumination path, where each illumination beam has an associated area on the front surface of the article;
• producing at least two signals containing different phase information in response to said at least one illumination beam after modification by said article;
• and
• determining said variations in the phase or amplitude of modified illumination beams at associated front surface area(s) according to said signals,
• wherein said providing or producing employs a Zernike plate with orthogonally polarized, complementary +/−α degree Zernike point spread functions, where α is between the values of 0 and 180 degrees.