Heterodyne moiré interferometry for measuring corneal surface profile
| Autor: | Wei-Yao Chang, Han Ying Sun, Shyan Tarng Chen, Jung Kai Tseng, Ken-Yuh Hsu, Jing-Heng Chen, Der Chin Chen, Kun-Huang Chen |
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| Rok vydání: | 2014 |
| Předmět: |
Heterodyne
Materials science business.industry Mechanical Engineering Physics::Medical Physics Phase (waves) Moiré pattern Grating Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials Interferometry Sine wave Optics Talbot effect Electrical and Electronic Engineering Projection (set theory) business |
| Zdroj: | Optics and Lasers in Engineering. 54:232-235 |
| ISSN: | 0143-8166 |
| DOI: | 10.1016/j.optlaseng.2013.07.013 |
| Popis: | This study proposes an accurate method for reconstructing the corneal surface profile. By applying a constant velocity to the projection grating along the grating plane, a series of sampling points of the sinusoidal wave, which behaves in the manner of heterodyne interferometric signals, can be recorded using a CMOS camera. The phase distribution of the moire fringes can then be obtained using the IEEE 1241 least-square sine fitting algorithm and two-dimensional (2D) phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into a specially derived equation. To validate the proposed method, the corneal surface of a pig eyeball was measured. The measurement resolution was approximately 3.5 μm. Because of the introduction of the Talbot effect, the projection moire method, and heterodyne interferometry, this approach provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution. |
| Databáze: | OpenAIRE |
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