We developed a high brightness ophthalmic photocoagulator with an orange fiber laser source. In order to improve brightness, a simple optical irradiation system (simple delivery) was used which achieved experimentally a beam diameter of 6.8 μm on a focal plane. From wavefront analysis, it was verified that the simple delivery has much reduced residual aberrations over the conventional optical system (zoom delivery) tested for comparison. In irradiation experimentation, an 11.5 μm diameter burn

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... ark was observed on coagulation test paper and a 12.7 μm coagulation mark on a pseudo-biological sample. The difference between the actual beam diameter and irradiation results is due to thermal diffusion property of the sample media. A photocoagulator with a beam of this improved brightness is expected to be particularly applicable to microsurgery in ophthalmic treatment.