Lensometer with autocollimation and a square Ronchi grid

Area of Science:

• Optics and Photonics
• Ophthalmology Instrumentation

Background:

• Accurate measurement of lens refractive power is crucial for vision correction.
• Existing lensometers can be expensive or bulky, necessitating simpler alternatives.

Purpose of the Study:

• To design, construct, and validate a novel lensometer utilizing an autocollimation system and a square Ronchi grid.
• To assess the performance of this new lensometer for various lens types, including monofocal, astigmatic, bifocal, and progressive lenses.

Main Methods:

• The lensometer employs an autocollimation system and a square Ronchi grid to identify the focal plane by observing spot patterns or fringe minima.
• Refractive and cylindrical powers are determined by analyzing fringe transformations for astigmatic lenses.
• Progressive lens analysis involves tracking a zero-spot circle's movement relative to the grid.

Main Results:

• The developed lensometer successfully measured the refractive powers of monofocal, astigmatic, bifocal, and progressive lenses.
• Measurements demonstrated high precision, with errors comparable to those of a commercial lensometer.
• The system proved effective in identifying focal planes and determining lens parameters.

Conclusions:

• The designed lensometer is a compact, cost-effective, and precise instrument for ophthalmic lens power measurement.
• Its performance is on par with commercial lensometers, offering a viable alternative.
• This technology has potential applications in optometry and optical manufacturing.