Vibration insensitive interferometer using sinusoidal phase-modulation and feedback control

Osami Sasaki; Hidetaka Iwai; Takamasa Suzuki

doi:10.1117/12.666829

9 December 2005 Vibration insensitive interferometer using sinusoidal phase-modulation and feedback control

Osami Sasaki, Hidetaka Iwai, Takamasa Suzuki

Proceedings Volume 6024, ICO20: Optical Devices and Instruments; 60240N (2005) https://doi.org/10.1117/12.666829
Event: ICO20:Optical Devices and Instruments, 2005, Changchun, China

Abstract

It is easy to extract a signal proportional to a phase fluctuation from a sinusoidally phase-modulated interference signal. This fluctuation is caused by mechanical vibration or air turbulence. In a sinusoidal phase-modulating interferometer using a laser diode (LD) the phase fluctuation is reduced by changing the injection current of the LD with a feedback control system. This control is very useful to a Fizeau type interferometer for surface profile measurement of a large size object. IC wafers of 100 mm diameter are measured with an interferometer insensitive to mechanical vibration and air turbulence. The phase fluctuation with nearly constant amplitude which corresponds to 30nm in surface height is reduced by about 10%. However the reduction in the phase fluctuation is not performed well for an instantaneous and large phase fluctuation. In order to be insensitive to all kinds of phase fluctuations the feedback signal is always observed, so that the interference signal is captured when the amplitude of the feedback signal is less than a specified level during the capturing time of 0.53 s. Thus surface profiles of the IC wafers can be measured with a high repeatability of a few nm even when any kind of vibration exists.

Citation Download Citation

Osami Sasaki, Hidetaka Iwai, and Takamasa Suzuki "Vibration insensitive interferometer using sinusoidal phase-modulation and feedback control", Proc. SPIE 6024, ICO20: Optical Devices and Instruments, 60240N (9 December 2005); https://doi.org/10.1117/12.666829

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
6 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Interferometers

Feedback control

Signal detection

Phase interferometry

Charge-coupled devices

Semiconducting wafers

Feedback signals

Show All Keywords

Keywords/Phrases

Search In:

Publication Years