The invention relates to a lens structure, in particular to the lens structure which has safe and reliable sealing, realizes the in-situ
optical observation under a high-temperature and high-pressure fluid environment (the
maximum temperature and the
maximum pressure can be 350 DEG C / 20MPa) as well as the application thereof, and solves the sealing and the visual (observation) problems under the high-temperature and high-pressure environment. The lens structure is assembled on an
autoclave, and is composed of a pressure cap, a butterfly-shaped
washer, a flat
washer, a lens, an O-shaped ring, a lens
barrel, a lens
mount, a
graphite washer, a clamping ring and a gland. When assembled, the components such as the pressure cap, the washers, the lens, and the like extend into the
autoclave through the lens
mount; then the gland is screwed on the lens
mount until clamping the clamping ring and the washers tightly. In order to ensure that the lens
barrel structure can stably work for a long time under the high-temperature fluid environment and can realize the high-quality in-situ
optical observation, a single-
crystal sapphire wafer with high high-temperature strength, good
corrosion resistance and excellent optical performance is taken as the lens material. Besides, the invention increases the
luminous flux through designing the lens
barrel into a conical structure, thereby facilitating the realization of the in-situ
optical observation.