JP2018081232A5 - - Google Patents

Claims (8)

Temperature coefficient dn / dT of the refractive index is negative, such that the magnitude of the focus shift amount f _b by the thermal lens effect is less than 2 times the size of the focus shift amount f _a due to thermal expansion, the thickness t and An optical lens, wherein the diameter D is selected. When the radius of curvature is R, the focal length before thermal expansion and the thermal lens effect occurs is f, the refractive index is n, the temperature difference between the center and the end is ΔT ° C., and the linear expansion coefficient is α, the following equation is obtained. All are true

The optical lens according to claim 1. A laser processing apparatus comprising the optical lens according to claim 1, and processing a workpiece with laser light through the optical lens. The laser processing apparatus according to claim 3, wherein the optical lens is used as a condenser lens. 5. The laser processing apparatus according to claim 3, wherein the optical lens is used as a protective lens that is provided behind the condenser lens on the optical path of the laser light and protects the condenser lens. The laser processing apparatus according to claim 3, wherein the optical lens is used for all lenses provided on an optical path of the laser light. A detector for detecting a convergence state of the laser light in an optical path until it is incident on the condenser lens;
A driving device for driving the condenser lens along the optical path based on a detection result of the detector;
The laser processing apparatus according to claim 4, comprising: The laser processing apparatus according to claim 7, wherein the optical lens is used for all the lenses provided on the optical path after the detection position where the detector detects the convergence state.