Laser device and laser anneal device

A laser anneal device comprising:

• (1) a laser device including a laser oscillator configured to output pulse laser light;
• (2) an optical pulse stretcher (OPS) device disposed on an optical path of the pulse laser light output from the laser oscillator and including a first OPS configured to stretch a pulse time width of the pulse laser light incident on the first OPS, by transmitting a part of the pulse laser light and causing the other part of the pulse laser light to circulate through a delay optical path and to be output, and in Which a delay optical path length L(1) as a length of the delay optical path of the first OPS being in a range of the following expression (A);
• and
• (3) an anneal device configured to anneal a semiconductor thin film by using the pulse laser light stretched by the OPS device,
• ΔT75%×c≤L(1)≤ΔT25%×c (A),
• where ΔTa % is a time full-width of a position at which light intensity represents a value of a % with respect to a peak value in an input waveform of the pulse laser light that is output from the laser oscillator and incident on the OPS device, and c is light speed.