An optical device (44) includes fluid circulating member link sections (446) that can link a plurality of fluid circulating members (448). The fluid circulating member link sections (446) are arranged respectively between a main tank (445) and an optical device main body (440) and between a radiator (447) and the optical device main body (440) to allow the optical device main body (440) to be fitted to and removed from the main tank (445) and the radiator (447).