Attenuator device and laser processing apparatus
An attenuator device includes: a first window pair including a pair of first windows having a pair of first surfaces extending to form a Brewster's angle with an optical axis; a rotation holding portion which holds the first window pair to be rotatable around the optical axis; a second window pair including a pair of second windows having a pair of second surfaces extending to form a Brewster's angle with the optical axis; and a λ/4 phase element which gives a phase difference of λ/4 between a polarized component parallel to an optical axis and a polarized component orthogonal to the optical axis when a wavelength of laser light is λ. 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°.
1 . 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.
2 . The attenuator device according to claim 1 ,
wherein the first window pair, the rotation holding portion, and the second window pair are fixed to each other to form one unit.
3 . The attenuator device according to claim 1 ,
wherein the first window pair and the second window pair are disposed inside a common housing.
4 . The attenuator device according to claim 3 ,
wherein the housing is provided with a heat dissipation structure.
5 . The attenuator device according to claim 1 , further comprising:
a controller which controls the rotation holding portion so that a rotation angle of the first window pair is to be a rotation angle in accordance with a target intensity.
6 . The attenuator device according to claim 5 ,
wherein the controller controls the rotation holding portion so that the rotation angle of the first window pair is to be a rotation angle in accordance with a target intensity based on a relationship between the rotation angle of the first window pair and an attenuation rate of the laser light due to the first window pair and the second window pair.
7 . A laser processing apparatus comprising:
a light source which outputs the laser light; and
the attenuator device according to claim 1 .
8 . The attenuator device according to claim 4 ,
wherein the heat dissipation structure includes a plurality of plate-shaped heat dissipation fins provided on an outer surface of the housing.
9 . The laser processing apparatus according to claim 7 ,
wherein the light source is a carbon dioxide laser oscillator.