Detection and discrimination of particles on and below smooth surfaces by laser scattering with polarization measurement

Fan Wu; Yubin Du; Pengfei Zhang; Yanwei Li; Yongying Yang

doi:10.1117/12.2528373

3 September 2019 Detection and discrimination of particles on and below smooth surfaces by laser scattering with polarization measurement

Fan Wu, Yubin Du, Pengfei Zhang, Yanwei Li, Yongying Yang

Author Affiliations +

Proceedings Volume 11102, Applied Optical Metrology III; 111021F (2019) https://doi.org/10.1117/12.2528373
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

The inspection of particles plays an important role in quality control of smooth surfaces, such as optics and silicon wafers. The difficulty of inspection lies not only in the high-resolution detectivity for small-size particles, but also in the need to distinguish among different types of particles due to their different damages and re-work processes. This paper proposes a detection and discrimination method of the particles on (surface particles) and below smooth surfaces (subsurface particles) by laser scattering with polarization measurement. The incident laser beam passes through a polarization state generator (PSG) to illuminate the smooth surface. A large proportion of the particle-induced scattered light is detected after collected by an ellipsoidal mirror. Meanwhile, in the blind area of the ellipsoidal mirror, a small amount of scattered light enters the polarization measurement channel, where a polarization state analyzer (PSA) is used to finally obtain a two-dimensional polarization signal for discriminating the two types of particles. Then, by a nonlinear global search combined with the theoretical models for polarized light scattering from particles, the optimal polarization measurement state of the PSG and the PSA is obtained to maximize the separability between the surface particles and subsurface particles on the acquired polarization signals. This method takes full advantage of the polarization of scattered light, and with one single scan the inspection for the whole surface can be accomplished. Finally, experimental results demonstrate the effectiveness and accuracy of the method.

Citation Download Citation

Fan Wu, Yubin Du, Pengfei Zhang, Yanwei Li, and Yongying Yang "Detection and discrimination of particles on and below smooth surfaces by laser scattering with polarization measurement", Proc. SPIE 11102, Applied Optical Metrology III, 111021F (3 September 2019); https://doi.org/10.1117/12.2528373

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
10 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Particles

Polarization

Light scattering

Mueller matrices

Laser scattering

Computer simulations

Scatter measurement

Show All Keywords

Keywords/Phrases

Search In:

Publication Years