Flat Plate Magnifier
Recommended reading in Optical Engineering.
If you are a senior optics and photonics professional, you may have noticed that your eyesight is not quite as good as it used to be. Reading glasses can help considerably, but sometimes it would be nice to have just a little bit of magnification.
An interesting article published in the September 2014 issue of Optical Engineering entitled “Flat-plate magnifier for magnifying the view of a distant object” attempts to address this problem.
Lead author Masataka Shirasaki (USA), along with Takehiro Kodaira, Hiroshi Yamaguchi, and Tsuneo Takei of Nittoh Kogaku in Japan, seek to develop a flat optic that can be placed in an eyeglass frame to provide 3x magnification over a large part of the ocular field of view.
To achieve magnification with a 3- to 4-mm plastic plate, they mated a two-dimensional array of two-mirror, micro-magnifying telescopes to a ray angle adjuster plate that directs the magnified ray bundles toward the center of rotation of the eye.
The researchers then made a prototype magnifier using a plastic mold manufactured with high-precision, multi-axis diamond turning. Aluminum coating was used for the mirror surfaces. The prototype provided the requisite magnification but lacked image sharpness due to distortion and roughness of the parabolic micro-magnifier surfaces.
The authors describe their innovation with design equations and illustrate the primary components with figures.
Perhaps we’ll have to wait for more refinement before we can buy a pair of these hands-free magnifiers at the local market or optometrist.
–SPIE Fellow Michael T. Eismann is a member of the SPIE Board of Directors and editor in chief of Optical Engineering.
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