| 摘要 |
A method for in vitro evaluation of focal length changes in a lens is disclosed, involving the steps of projecting parallel laser beams through the lens at at least two points, examining the convergence of the beams after exiting the lens to determine the focal length of the lens, and after a period of time, repeating these steps and comparing the focal length. Preferably, a scanning laser is used so that a number of beams pass through different spots on the lens, so that the spherical aberration of the lens may also be determined and compared over time. Apparatus is disclosed for carrying out the method, comprising a carousel plate having a number of spaced holes for receiving lens containers. A carousel drive servo motor rotates the carousel from lens container position to lens container position. A helium-neon laser is mounted horizontally on an X-Y table, and the laser beam is deflected upwardly through a lens held in a lens container. Mirrors provide a video camera with two views of the lens focal point area, the viewpoints being offset from each other by 90 degrees. The video camera signal is fed to a personal computer for analysis. A display monitor and printer are connected to the computer. The software may be directed to display and print the actual video camera image, or to digitize the information and produce a display or printout illustrating the spherical aberration of the lens.
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