Encoder device, method for measuring moving amount, optical apparatus, exposure apparatus, exposure method and method for producing device

An encoder device which measures a relative moving amount between a first member and a second member, a diffraction grating having a diffraction pattern of which periodic directions are a first direction and a second direction crossing the first direction being provided on the first member, the encoder device comprising:

• a first optical member configured to direct a measuring light toward a surface of the diffraction grating along a first axis;
• a second optical member which is provided on the second member and which is configured to deflect first, second, third and fourth diffracted lights generated, by the measuring light deflected from the diffraction grating, along second, third, fourth and fifth axes, respectively, back toward the diffraction grating, the first direction being a direction in a first plane including the second and third axes and the second direction being a direction in a second plane including the fourth and fifth axes;
• a third optical member configured to deflect each of the first, second, third and fourth diffracted lights from the diffraction grating toward the second optical member multiple times in a direction toward the first axis;
• and
• first, second, third and fourth photo-detectors configured to receive fifth, sixth, seventh and eighth diffracted lights generated by the first, second, third and fourth diffracted lights deflected from the diffraction grating, respectively,
• wherein the third optical member is configured to deflect each of the fifth, sixth, seventh, and eighth diffracted lights multiple times.