Determination of the axial stiffness of an optical trap with information entropy signals

Mincheng Zhong; Jinhua Zhou; Jianguang Wu; Yinmei Li

doi:10.1117/12.837347

1 December 2009 Determination of the axial stiffness of an optical trap with information entropy signals

Mincheng Zhong, Jinhua Zhou, Jianguang Wu, Yinmei Li

Proceedings Volume 7507, 2009 International Conference on Optical Instruments and Technology: Optical Trapping and Microscopic Imaging; 75070J (2009) https://doi.org/10.1117/12.837347
Event: International Conference on Optical Instrumentation and Technology, 2009, Shanghai, China

Abstract

Optical tweezers has been used to manipulate micro-sized particles for many years, and has been widely used in various applications. The axial trapping stiffness is one of the most important parameters to evaluate the trapping ability of an optical tweezers. In this paper, we calibrated the axial optical stiffnesses for micro-sized polystyrene spheres. When an external force was applied to particle held by an optical trap, the particle was displaced from the trap center by an amount proportional to the applied force. We displaced the particle from the trap center by applying triangular waves of varying velocity, and the varying velocity was obtained by altering the frequency of the triangular waves. In this case the particle has two balance position distributed at two-side of the trap center. The calibration of the axial position was critical to the measurement of axial optical stiffness. In this paper, the axial displacement between the balance position and the trap center was calibrated with image information entropy signals. According to Stokes Law, when the axial displacement of the particle relative to the external force was known, the axial optical stiffness can be measured, and this method was known as viscous drag method. The stiffnesses for a 2μm-diameter at different trapped depth were measured. Typical values for axial optical stiffness of our optical tweezers were between 4.0 and 7.5 pN/μm when the laser power was 35mW. Dependence of axial optical trapping stiffness on the diameter of the particles was measured with viscous drag method. At last, the origin of the measurement error was discussed.

Citation Download Citation

Mincheng Zhong, Jinhua Zhou, Jianguang Wu, and Yinmei Li "Determination of the axial stiffness of an optical trap with information entropy signals", Proc. SPIE 7507, 2009 International Conference on Optical Instruments and Technology: Optical Trapping and Microscopic Imaging, 75070J (1 December 2009); https://doi.org/10.1117/12.837347

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
7 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Particles

Optical tweezers

Calibration

Optical spheres

Image information entropy

Charge-coupled devices

Optical calibration

Show All Keywords

Keywords/Phrases

Search In:

Publication Years