Ultrasonic generator and detector using an optical mask having a grating for launching a plurality of spatially distributed, time varying strain pulses in a sample

Patent · Tue Jan 01 00:00:00 EST 2002

OSTI ID:874392

Maris, Humphrey J ^[1]

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1. Barrington, RI

A method and a system are disclosed for determining at least one characteristic of a sample that contains a substrate and at least one film disposed on or over a surface of the substrate. The method includes a first step of placing a mask over a free surface of the at least one film, where the mask has a top surface and a bottom surface that is placed adjacent to the free surface of the film. The bottom surface of the mask has formed therein or thereon a plurality of features for forming at least one grating. A next step directs optical pump pulses through the mask to the free surface of the film, where individual ones of the pump pulses are followed by at least one optical probe pulse. The pump pulses are spatially distributed by the grating for launching a plurality of spatially distributed, time varying strain pulses within the film, which cause a detectable change in optical constants of the film. A next step detects a reflected or a transmitted portion of the probe pulses, which are also spatially distributed by the grating. A next step measures a change in at least one characteristic of at least one of reflected or transmitted probe pulses due to the change in optical constants, and a further step determines the at least one characteristic of the sample from the measured change in the at least one characteristic of the probe pulses. An optical mask is also disclosed herein, and forms a part of these teachings.

• Research Organization: Brown Univ., Providence, RI (United States)
• DOE Contract Number: FG02-86ER45267
• Assignee: Brown University Research Foundation (Providence, RI)
• Patent Number(s): US 6381019
• OSTI ID: 874392
• Country of Publication: United States
• Language: English

Related Subjects

ultrasonic
generator
detector
optical
mask
grating
launching
plurality
spatially
distributed
time
varying
strain
pulses
sample
method
disclosed
determining
characteristic
contains
substrate
film
disposed
surface
step
placing
free
top
bottom
placed
adjacent
formed
features
forming
directs
pump
individual
ones
followed
probe
pulse
detectable
change
constants
detects
reflected
transmitted
portion
measures
due
determines
measured
forms
teachings
pump pulse
/356/73/374/