To make liquid sufficiently movable in a short time and to prevent the uncomfortable transient optical strain induced by the flow of the liquid by changing the spacings between rigid lenses and expandable films, thereby changing focal lengths.
The lens assembly includes the rigid lenses 20 and the expandable films 22. The spaces between the rigid lenses 20 and the expandable films 22 are filled with the liquid 25 having the same refractive index as the refractive index of the material of the lenses 20. Since the liquid 25 is hardly compressible, the expandable films 22 expand to enhance the refraction performance of the light of the assembly as a fore ring 23 approaches a rear ring 21. Finger manipulation type positioning devices which exist on the outer side of a frame 10 and preferably exist in one of actuator positions are fixed to a band 31 by spot welding or other method. A wearing person moves the band 31 and adjusts the position of a cam 30 by moving one of the finger manipulation type positioning devices. The focal lengths of the lenses may be thereby adjusted as desired.
DANIEL E FEDEERU
SOULE IPUSUTEIN
