Laser device and exposure device using the same

摘要

In a laser module, a laser beam which is emitted from a laser element is focused by a condensing optical system and caused to enter an incidence end of an optical fiber. A laser device is provided with a plurality of these laser modules. Emission end portions of the optical fibers are bundled to form a laser emission portion. A thickness of cladding h of each optical fiber is set to a value calculated in accordance with the following equation: 1 $\begin{array}{c}\mathrm{cladding}\\ \mathrm{thickness}h\end{array}\le (\sqrt{\frac{\begin{array}{c}\mathrm{emission}\mathrm{light}\mathrm{amount}\\ \mathrm{of}\mathrm{one}\mathrm{laser}\mathrm{module}W\end{array}}{\begin{array}{c}\mathrm{required}\\ \mathrm{intensity}C\end{array}x\begin{array}{c}\mathrm{packing}\\ \mathrm{ratio}P\end{array}}}-\begin{array}{c}\mathrm{core}\\ \mathrm{diameter}\&it\end{array}$