Attenuator device and laser processing apparatus

An attenuator device comprising:

• a first window pair which includes a pair of first windows on which laser light is incident along an optical axis, each of the pair of first windows including a pair of first surfaces extending to form a Brewster's angle with the optical axis, one pair of first surfaces of the pair of first windows is inclined on a side opposite to the other pair of first surfaces of the pair of first windows with respect to the optical axis;
• a rotation holding portion which holds the first window pair so that the first window pair is rotatable around the optical axis;
• a second window pair which includes a pair of second windows, each of the pair of second windows including a pair of second surfaces extending to form a Brewster's angle with the optical axis, one pair of second surfaces of the pair of second windows is inclined on a side opposite to the other pair of second surfaces of the pair of second windows with respect to the optical axis;
• and
• a λ/4 phase element which is disposed so that the laser light is incident after passing through the first window pair and the second window pair in this order and gives a phase difference of λ/4 between a polarized component parallel to an optical axis of the λ/4 phase element and a polarized component orthogonal to the optical axis of the λ/4 phase element when a wavelength of the laser light is λ,
• wherein the second window pair is disposed so that a vibration direction of a P-polarized component transmitted through the second window pair is inclined with respect to the optical axis of the λ/4 phase element by 45° when viewed from a direction parallel to the optical axis along which the laser light is incident.