Ex Parte Maier et al

Patent Trial and Appeal Board

Feb 14, 2017

13391218 (P.T.A.B. Feb. 14, 2017)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
13/391,218 05/02/2012
24972 7590 02/16/2017
NORTON ROSE FULBRIGHT US LLP
1301 Avenue of the Americas
NEW YORK, NY 10019-6022
FIRST NAMED INVENTOR
Martin Maier
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www .uspto.gov
ATTORNEY DOCKET NO. CONFIRMATION NO.
1019117352 4461
EXAMINER
PLESZCZYNSKA, JOANNA
ART UNIT PAPER NUMBER
1783
NOTIFICATION DATE DELIVERY MODE
02/16/2017 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address( es):
nyipdocket@nortonrosefulbright.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte MARTIN MAIER, KAI VON GARNIER, WILFRIED AICHELE,
JUERGEN LANDER, NIKOLAUS HAUTMANN, MICHAEL HONER,
and JENS KOENIG
____________

Appeal 2016-000932
Application 13/391,218
Technology Center 1700
____________
Before ROMULO H. DELMENDO, CHRISTOPHER C. KENNEDY, and
MICHAEL G. McMANUS, Administrative Patent Judges.
McMANUS, Administrative Patent Judge.
DECISION ON APPEAL
The Examiner finally rejected claims 16–29, 35–39, and 41–45 of
Application 13/391,218 under 35 U.S.C. § 103(a) as obvious and
provisionally rejected claims 16–29, 36–39, and 42–45 on the ground of
nonstatutory obviousness-type double patenting. Final Act. (Nov. 6, 2014).
Appellants1 seek reversal of these rejections pursuant to 35 U.S.C. § 134(a).
We have jurisdiction under 35 U.S.C. § 6.

1 Robert Bosch GmbH is identified as the real party in interest. Appeal
Br. 1.
Appeal 2016-000932
Application 13/391,218
2
For the reasons set forth below, we AFFIRM.
BACKGROUND
The present application relates generally to a composite article where
one component has a contact surface having a “microstructure overlaid by a
nanostructure.” Spec. 3. The contact surface is taught to ensure “an
improved adhesion.” Id. The claims at issue further require a second
component attached to the first by an adhesive layer. Appeal Br. (Claims.
App. 1).
Claims 16, 19, and 45 are representative of the pending claims and are
reproduced below:
16. A component composite, comprising:
a first component having a first contact surface, the first contact
surface having a surface structure which has a microstructure
overlaid by a nanostructure;
at least one second component having a second contact surface;
and
an adhesive layer situated for integral connection between the
first contact surface of the first component, and the second
contact surface of the second component.

19. The component composite as recited in claim 16, wherein
at least one of: i) the microstructure has microstructure
elements having a diameter in a size range between
approximately 1 μm and approximately 999 μm, and ii) the
nanostructure has nanostructure elements having a diameter in a
size range between approximately 1 nm and approximately 999
nm.

Appeal 2016-000932
Application 13/391,218
3
45. The component composite as recited in claim 16,
wherein:
the microstructure includes protruding microstructure elements,
depressed microstructure elements, and areas between the
protruding microstructure elements and the depressed
microstructure elements[ ]; and
the nanostructure includes first nanostructure elements located
on the protruding microstructure elements, second
nanostructure elements located in the depressed microstructure
elements, and third nanostructure elements located in the areas
between the protruding microstructure elements and the
depressed microstructure elements.
Appeal Br. (Claims App. 1, 3).
REJECTIONS
On appeal, the Examiner maintains the following rejections:
1. Claims 16–29, 36–39, and 42–45 are provisionally rejected on
the basis of nonstatutory obviousness-type double patenting. Final Act. 2–3.
2. Claims 16–18, 20–29, 35–39, 41, and 43–45 are rejected under
35 U.S.C. § 103(a) as being unpatentable over Il et al. (US 2008/0206520
A1, pub. Aug. 28, 2008) (hereinafter “Il”) in view of Tsukamoto et al.
(Masahiro Tsukamoto et al., Periodic Microstructures Produced by
Femtosecond Laser Irradiation on Titanium Plate, Vacuum 80 (2006) 1346–
1350) (hereinafter “Tsukamoto”). Id. at 4–10.
3. Claim 19 is rejected under 35 U.S.C. § 103(a) as being
unpatentable over Il in view of Tsukamoto and further in view of Akahoshi
et al. (US 4,970,107, iss. Nov. 13, 1990) (hereinafter “Akahoshi”). Id. at 10.
4. Claim 42 is rejected under 35 U.S.C. § 103(a) as being
unpatentable over Il in view of Tsukamoto and further in view of
Appeal 2016-000932
Application 13/391,218
4
Levendusky et al. (US 5,919,517, iss. July 6, 1999) (hereinafter
“Levendusky”). Id. at 11.
DISCUSSION
Rejection 1. The Examiner provisionally rejected claims 16–29, 36–
39, and 42–45 on the basis of nonstatutory obviousness-type double
patenting over claims 16, 18–25, 31, and 34 of copending U.S. Patent
Application No. 12/737,566. Appellants do not present argument in
opposition to such rejection, but rather state that such provisional rejection
does not form part of the present appeal because it is not yet a rejection.
Appeal Br. 11. Because Appellants advance no argument on appeal
traversing the provisional nonstatutory double patenting rejection, it is
summarily sustained. See 37 C.F.R. § 41.37(c)(1)(iv). Cf. Ex parte Frye, 94
USPQ2d 1072, 1075 (BPAI 2010) (“If an appellant fails to present
arguments on a particular issue—or, more broadly, on a particular
rejection—the Board will not, as a general matter, unilaterally review those
uncontested aspects of the rejection”) (citing Hyatt v. Dudas, 551 F.3d 1307,
1313–14 (Fed. Cir. 2008)).
Rejection 2. The Examiner rejected claims 16–18, 20–29, 35–39, 41
and 43–45 as obvious over Il in view of Tsukamoto. Final Act. 4.
Appellants assert that such rejection is in error as the Examiner has not
stated an adequate basis why a person of ordinary skill in the art would have
combined the teachings of Il and Tsukamoto, Appeal Br. 4–6, and that such
a person would not have been able to combine such teachings without undue
experimentation, id. at 6–7. Appellants additionally argue that the cited
references do not teach the nanostructure elements located on the
microstructure elements as required by claim 45. Id. at 7–8.
Appeal 2016-000932
Application 13/391,218
5
Reason to Combine the Teachings of Il and Tsukamoto
Appellants advance several arguments in support of their argument
that the Examiner has not stated a sufficient reason why a person of ordinary
skill in the art would have been led to combine the teachings of the cited
references. Appellants assert that Il teaches a continuous wave (“unpulsed”)
laser while Tsukamoto teaches a pulsed laser; that the Il process yields a
layer of metal hydroxide while Tsukamoto teaches no such layer; and that Il
teaches an irregular surface morphology, while Tsukamoto teaches regularly
arranged microstructures and nanostructures. Id. at 4; Reply 2. Appellants
argue that a person of ordinary skill in the art would have had no reason to
combine such dissimilar processes. Id. at 4
In response, the Examiner asserts that the rationale for combination
“does not discuss combination of the processes disclosed in the references.”
Answer 13. Rather, “it is the structures of the references that were
combined, not the processes, and the rationale was the improvement of
bonding properties.” Id. at 15. The Examiner further provides that “both
references teach using laser for forming surface structures, both form
microstructures, and in addition Tsukamoto teaches formation of
nanostructures, and both teach that these formations help to provide the
surfaces with bonding properties.” Answer 14.
Il teaches that surface energy is increased not just by formation of the
metal hydroxide layer but also by the increase in “contact area” arising from
the irregularities. Il ¶ 80. Similarly, Tsukamoto teaches that “[f]ormation of
microstructures on the materials is a useful and important technology
since . . . adhesion of the film to the substrate depend on the surface
morphology of the material.” Tsukamoto 1346.
Appeal 2016-000932
Application 13/391,218
6
“The combination of familiar elements according to known methods
is likely to be obvious when it does no more than yield predictable results.”
KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007). Here, Il teaches
each element of claim 16 other than a “microstructure overlaid by a
nanostructure.” See Il, Fig. 2. Tsukamoto teaches a microstructure overlaid
by a nanostructure. Final Act. 4; Tsukamoto 1347 (“periodic nanostructures
were also superimposed on the parallel periodic microstructures as shown”).
In view of Tsukamoto’s teaching that adhesion depends upon surface
morphology and Il’s teaching that increased contact area enhances adhesion,
the proposed combination of the structure of Il with the surface taught by
Tsukamoto to have microstructure overlaid by nanostructures in order to
enhance adhesion would have been no more than the combination of known
elements to yield a predictable result.
Undue Experimentation
Appellants argue that a person of ordinary skill in the art would not
have been able to combine the processes of Il and Tsukamoto without
engaging in undue experimentation.
The Examiner has indicated, however, that “it is the structures of the
references that were combined, not the processes.” Answer at 15.
Accordingly, the rejection does not depend upon the ability of a person of
ordinary skill in the art to combine such processes. Even were this not the
case, mere difference in two prior art processes does not necessarily mean
that a person having ordinary skill in the art would have been subjected to
undue experimentation in combining the prior art structures to arrive at the
claimed invention. In re Antor Media Corp., 689 F.3d 1282, 1287–1288
(Fed. Cir. 2012) (prior art publications are presumed to be enabling).
Moreover, “[o]bviousness does not require absolute predictability of
Appeal 2016-000932
Application 13/391,218
7
success. . . . For obviousness under § 103, all that is required is a reasonable
expectation of success.” In re O’Farrell, 853 F.2d 894, 903–04 (Fed. Cir.
1988). Here, Appellants have not shown that a person of ordinary skill in
the art would not have had a reasonable expectation of success in combining
the nanostructure and microstructure of Tsukamoto with the remaining
features of Il.
Accordingly, Appellants have not shown reversible error in the
Examiner’s determination that claims 16–18, 20–29, 35–39, 41, and 43–44
are obvious over Il in view of Tsukamoto.
Claim 45
The Examiner additionally rejected claim 45 as obvious over Il in
view of Tsukamoto. Final Act. 10. Appellants allege error in this rejection
on the basis that neither Il nor Tsukamoto teaches the nanostructure elements
located on the microstructure elements. The Examiner finds that Tsukamoto
teaches nanostructure elements located on protruding and depressed
microstructures as well as the space therebetween. Id. (citing Tsukamoto
1347, 1349). Tsukamoto teaches, inter alia, that the “periodic nanostructures
were also superimposed on the parallel periodic microstructures as shown in
Fig. 2(e).” Tsukamoto 1347. In addition, Tsukamoto provides that
As Figs. 2(b) and (e) show, when the parallel periodic
microstructures were produced, the periodic nanostructures
were also created and the parallel periodic microstructures were
always oriented to the direction perpendicular to the periodic
nanostructures’ direction.

Tsukamoto 1349; see also id. at 1348 (Fig. 3(b) and (e)).2

2 For convenience, we attach a copy of the Tsukamoto reference that is more
legible than that found in the prosecution history.
Appeal 2016-000932
Application 13/391,218
8
In view of the disclosure of Tsukamoto, Appellants have not shown
reversible error in the Examiner’s finding that Tsukamoto teaches a
nanostructure that includes first nanostructure elements located on the
protruding microstructure elements, second nanostructure elements located
in the depressed microstructure elements, and third nanostructure elements
located in the areas between the protruding microstructure elements and the
depressed microstructure elements.
Rejection 3. The Examiner rejected claim 19 as obvious over Il in
view of Tsukamoto and further in view of Akahoshi. Final Act. 10. Claim
19 depends from claim 16 and further requires “at least one of” i)
microstructures having a diameter in a size range between 1–999 µm and ii)
nanostructures having a diameter in a size range between 1 nm and 999 nm.
Appeal Br. (Claims App. 1). Appellants concede that Akahoshi teaches rod-
like projections having an average diameter between 5–10 nm. Appeal Br.
9.
Appellants argue that the claim limitation requiring microstructure
elements of the stated size is not taught by Akahoshi. Id. During
examination, claim terms must be given their broadest reasonable
construction consistent with the Specification. In re ICON Health and
Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007). Under such standard, a
claim requiring “at least one of” two limitations be met will be construed in
the disjunctive. That is, only one of the size limitations regarding
microstructure size or nanostructure size must be met. Here, Appellants
concede that Akahoshi teaches a feature satisfying the nanostructure
diameter size limitation.
Appellants additionally argue that “one of ordinary skill in the art
would not have been motivated, and indeed would not have understood how,
Appeal 2016-000932
Application 13/391,218
9
to combine the deposition and plating process of Akahoshi with the laser
irradiation processes of Il and Tsukamoto.” Appeal Br. 9. Thus, Appellants
argue that a person of ordinary skill in the art would not have had a
reasonable expectation of success.3 Id.; Reply Br. 8.
Akahoshi teaches that nanostructures having an average diameter of 5
to 10 nm can enhance bonding. Answer 20. As with Il and Tsukamoto,
above, the Examiner does not propose a hypothetical combination that
requires one to implement the process of Akahoshi. Rather, the Examiner
merely relies upon its teaching that structures of the given size may enhance
adhesion.
In this regard, Akahoshi teaches that “[t]o obtain high bonding
strength it is preferred to form further fine rod-like projections on the surface
of the knife-shaped projections after they are formed on the copper surface.”
Akahoshi 4:20–24. This is consistent with the basic principle taught by the
other references that greater contact area improves adhesion. Il ¶ 80;
Levendusky 9:45–49 (teaching that pre-treating by “surface roughening”
will improve adhesion); Tsukamoto 1346.
Accordingly, Appellants have not shown that a person of ordinary
skill would have lacked a reasonable expectation of success in making a
composite good having a contact surface having nanostructures falling
within the claimed range.

3 Appellants assert that a person of ordinary skill in the art “would not have
been motivated” to combine the references but do not support such
contention. Any such argument is, accordingly, waived. 37 C.F.R. §
41.37(c)(1)(iv).
Appeal 2016-000932
Application 13/391,218
10
Rejection 4. The Examiner rejected claim 42 as obvious over Il in
view of Tsukamoto and further in view of Levendusky. Claim 42 depends
from claim 16 with the further limitations that 1) the contact surface of the
second component is made of a thermoplastic and 2) the second component
overlies a “peripheral shoulder” of the first component. Appeal Br. (Claims
App. 3).
First, Appellants argue that Il lacks a teaching that the second contact
surface is made of a thermoplastic. In this regard, the Examiner finds that
several of the polymers taught by Il (polyethylene, polypropylene and
polyvinyl chloride) are known to be thermoplastic. Final Act. 11.
Appellants do not directly rebut such finding but instead point out that Il
does not explicitly teach that such polymers are “thermoplastic,” and further
that Il does not indicate that the specific resins are in a form suitable for use
as thermoplastics. Appeal Br. 10. Finally, they assert that use of a
thermoplastic would be incompatible with the curing process taught by Il.
Id.
Il teaches “[e]xamples of the counterpart member include a resin
molded article made from a resin material.” Il ¶ 60. Use in resin molding
suggests that a resin is thermoplastic. Further, the Examiner notes that a
thermoplastic resin is not incompatible with a curing process where the
melting temperature of the thermoplastic resin is higher than the curing
temperature of the curable resin used as an adhesive. Answer 21.
Accordingly, Appellants have not persuaded us of reversible error in the
Examiner’s finding that Il teaches to make a counterpart member from resin
known to be thermoplastic.
Appellants’ second argument regarding claim 42 is that the cited
references do not teach a counterpart member overlying a peripheral
Appeal 2016-000932
Application 13/391,218
11
shoulder. Appeal Br. 10–11; Reply Br. 10. The Examiner finds that the
second component taught by Il is a “counterpart” component, thus, it would
have been obvious to fully overlie the first component. Final Act. 11–12.
The Examiner further determines that the extent of overlap is merely a
design choice.
Appellants argue that modification to cover a peripheral shoulder is
not a mere change in size and that the Specification teaches the criticality of
coating the shoulder. Appeal Br. 10. Appellants further argue that one
component merely being a counterpart to another would not suggest that the
counterpart component should overlie the shoulder of the first component.
Appeal Br. 10–11.
“The combination of familiar elements according to known methods
is likely to be obvious when it does no more than yield predictable results.”
KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007). Here, a
thermoplastic component that covers two surfaces (or portions of two
surfaces) of another component is a familiar element. Combination of such
an element with a component having a contact surface yields only
predictable results. Further, “[a] person of ordinary skill is also a person of
ordinary creativity, not an automaton.” Id. at 421. A person of ordinary
creativity would readily understand that a thermoplastic component can
cover a single surface or one or more adjacent surfaces.
Accordingly, Appellants have not shown that the Examiner erred in
finding that Il teaches that the counterpart member may be made of a
thermoplastic resin or may cover a portion of the peripheral shoulder of the
first component.
Appeal 2016-000932
Application 13/391,218
12
CONCLUSION
The rejections of claims 16–29, 35–39, and 41–45 as obvious and
claims 16–29, 36–39, and 42–45 on the ground of nonstatutory obviousness-
type double patenting are sustained.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).
AFFIRMED

Notice of References Cited

Application/Control No.

13/391,218
Applicant(s)/Patent Under
Reexamination

Examiner

Pleszczynska
Art Unit

1700

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Masahiro Tsukamoto et al., Periodic Microstructures Produced by Femtosecond Laser Irradiation on Titanium Plate, 80 Vacuum
1346-1350 (2006).

V

W

X

*A copy of this reference is not being furnished with this Office action. (See MPEP § 707.05(a).)
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U.S. Patent and Trademark Office
PTO-892 (Rev. 01-2001) Notice of References Cited Part of Paper No.
Delete Last PageAdd A Page
Vacuum 80 (2006) 1346–1350
Periodic microstructures produced by femtosecond laser irradiation on
titanium plate
Masahiro Tsukamotoa,
, Keita Asukab, Hitoshi Nakanoc, Masaki Hashidad,
Masahito Kattoe, Nobuyuki Abea, Masayuki Fujitaf
aJoining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
bGraduate School of Engineering, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan
cSchool of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
dInstitute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
eCooperative Research Center, Miyazaki University, Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan
fInstitute for Laser Technology, Suita, Osaka 565-0871, Japan
Abstract
The periodic microstructures on titanium plate were formed by the irradiation of the femtosecond laser with the laser wavelength of
800 nm and the pulse length of 100 fs. They were oriented to the direction parallel to the laser polarization vector and their (parallel
periodic microstructures) period was 1.5–2.4 mm. The periodic nanostructures were also produced by the femtosecond laser ablation,
which were oriented to the direction perpendicular to the laser polarization vector and whose period was about 700 nm. Our results
indicated that the laser fluence required for the parallel periodic microstructures was higher than that for the periodic nanostructures.
The parallel periodic microstructures and the periodic nanostructures might be formed by an intensity modulation, which arose from the
interaction of the laser and its scattered wave with a surface wave. The number of laser pulses to irradiate Ti plate was increased from 10
to 110. From 50 pulses, microdots were generated on the hills of the parallel periodic microstructures. From 70 pulses, the parallel
periodic microstructures were varied to those with spatial modulation on the hills and the period of them was increased due to the
bonding of the hills.
r 2006 Elsevier Ltd. All rights reserved.
Keywords: Femtosecond laser; Laser ablation; Periodic microstructures; Periodic nanostructures; Titanium
1. Introduction
Formation of microstructures on the materials is a useful
and important technology since the tribological, frictional,
flow and hydrophilic properties, bioactivity, biocompat-
ibility and adhesion of the film to the substrate depend on
the surface morphology of the material. The femtosecond
laser is an advanced tool for precision material processing,
such as drilling, cutting and grooving into the metal [1].
The conventional method using the nanosecond laser gives
a heat-affected zone to the metal workpiece [2,3]. Laser
plume, including molten metal, vapor and plasmas, is
generated from the laser irradiation spot and also cause the
heat-affected zone and the morphological change of metal
surface. The heat-affected zone and the morphological
change limit the precision material processing for micro-
structure formation on metal. It is reported that the
femtosecond laser provides considerable advantages for the
hole formation in comparison with nanosecond lasers [2,3].
The advantages are based on very rapid creation of vapor
and plasma phase, negligible heat conduction, and the
absence of liquid phase. In addition to these advantages,
periodic nanostructures are self-organized in the femtose-
cond laser irradiated area [4–10]. The periodic nanostruc-
tures (grooves) lie perpendicular to the laser electric field
polarization vector. Thus, the grating vector of the periodic
nanostructures is parallel to the projection of the electric
field vector EL of the laser onto the material surface. The
periodic nanostructures formed by the femtosecond laser
ARTICLE IN PRESS
www.elsevier.com/locate/vacuum
0042-207X/$ - see front matter r 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.vacuum.2006.01.016

Corresponding author. Tel./fax: +81 6 6879 8675.
E-mail address: tukamoto@jwri.osaka-u.ac.jp (M. Tsukamoto).
ablation were similar to results observed for long pulse
ablation [11–14]. It was postulated that they were produced
by an intensity modulation, which arose from the interac-
tion of the incident and scattered wave with a surface wave
created from any periodic modulation in the surface. The
periods observed were ds ¼ lL= cos yi with s-polarization
and dp ¼ lL=ð1
sin yiÞ with p-polarization, where lL and
yi were the laser wavelength and the incident angle of the
laser, respectively [4,13,14]. When the incident angle of the
laser is 01, the period was derived from ds ¼ dp ¼ lL.
In this paper, we reported formation of the periodic
microstructures on the titanium (Ti) plate. The Ti is a
useful and important material in many industrial applica-
tions because of lower density, strong tensile strength, high
melting temperature and good chemical stability. In the
field of clinical orthopedics, the Ti or hydroxyapatite-
coated Ti is already used as biomaterials. A Ti plate was
irradiated with a femtosecond laser at an average laser
fluence of up to 1.50 J/cm2 under vacuum. To investigate
the dependence of the period of the periodic microstruc-
tures on the number of the laser pulses, a Ti plate was
irradiated by the femtosecond laser in the range of 10 to
110 laser pulses.
2. Experimental conditions
The schematic diagram of experimental setup is shown in
Fig. 1. A commercial femtosecond Ti: sapphire laser system
was employed in our experiments, which was based on the
chirped pulse amplification technique. This system pro-
vides laser pulses at wavelength of 800 nm and repetition
rate of 1 kHz. Pulse length and beam diameter of the laser
were 100 fs and about 4mm, respectively. Pulse length was
measured by a background-free second-order autocorre-
lator. An attenuator to reduce the output energy of the
laser composed of polarilizing filters. The laser beam was
focused on the Ti plate surface by a lens with a focal length
of 100mm, installed in a processing chamber as shown in
Fig. 1. Thickness and surface roughness (Ra) of the Ti
plate were 500 and 0.05 mm, respectively. The Ti plate’s
position was controlled with XYZ stages connected to a
computer. The processing chamber was pumped down with
a rotary pump to get the condition under vacuum (13.3 Pa).
A collimator and a mechanical shutter were installed on the
laser beam axis. Laser beam profile on the Ti plate surface
was measured with a monitoring system of laser beam
profile shown in Fig. 1. The beam diameter of the laser was
changed from 4 to 2mm with a collimator to improve the
beam profile and get the Gaussian laser beam profile on the
Ti plate surface. The Gaussian laser beam took the shape
of a circular with diameter of 50 mm at 1/e2 in intensity. In
the first experiment, 10 pulses of the laser irradiated the Ti
plate, which was obtained by opening the mechanical
shutter for 10ms, and the average laser fluence on the Ti
plate was varied from 0.25 to 1.5 J/cm2 by controlling the
attenuator. In the second experiment, the fluence was fixed
at 0.75 J/cm2 and number of the laser pulses was varied
from 10 to 110 by controlling the opening time of the
mechanical shutter. Microstructures produced by the laser
irradiation were observed with an optical microscope and a
scanning electron microscope (SEM).
3. Experimental results and discussion
SEM images of Ti plate surface irradiated with the
femtosecond laser for 0.25, 0.75 and 1.50 J/cm2 are shown
in Figs. 2(a)–(c), respectively. Higher magnification images
of Figs. 2(a)–(c), the center region of the irradiation area,
are shown in Figs. 2(d)–(f), respectively. As Figs. 2(a) and
(d) show, the periodic nanostructures were formed in the
irradiation area for 0.25 J/cm2. They were oriented to the
direction perpendicular to the laser electric field polariza-
tion vector, whose orientation was as same as those
reported in Refs. [4–10]. The period of the periodic
nanostructures in Figs. 2(a) and (d) was about 700 nm,
which was shorter than the period, 800 nm, derived from
ds ¼ dp ¼ lL at yi ¼ 0 (deg.). This result indicated that the
model in Refs. [4,13,14] has not yet been enough to
interpret the periodic nanostructures formation mechan-
isms on the Ti plate. For 0.75 J/cm2, there were two
regions, outer and center regions, in the irradiation area as
shown in Fig. 2(b). In the outer region of the irradiation
area, the periodic nanostructures were formed. In the
center area whose radius was about 20 mm, another
microstructures were observed. As shown in Fig. 2(b),
another microstructures were the periodic microstructures
(grooves), which lied parallel to the laser electric field
polarization vector. When the laser electric field polariza-
tion vector was rotated, the periodic microstructures
(parallel periodic microstructures) were also rotated. The
period of the parallel periodic microstructures was in the
range of 1.5–2.4 mm, which was 1.9–3.0 times longer than
the laser wavelength. The periodic nanostructures were also
superimposed on the parallel periodic microstructures as
shown in Fig. 2(e). The period of the periodic nanos-
tructures was about 700 nm. For 1.50 J/cm2, as Fig. 2(c)
shows, there were three regions, outer, middle and center
regions, in the irradiation area. Outer region had the
periodic nanostructures and middle region had the parallel
periodic microstructures with the periodic nanostructures
similar to the structures shown in Fig. 2(e). In the center
region, as Fig. 2(f) shows, the periodic nanostructures and
ARTICLE IN PRESS
Titanium plate
Lens
Femtosecond laser
Monitoring System of
laser beam profile
Processing chamber
Mechanical shutter
Energy attenuator
XY stages
Fig. 1. Schematic diagram of experimental setup.
M. Tsukamoto et al. / Vacuum 80 (2006) 1346–1350 1347
the parallel periodic microstructures were not produced.
These results indicated that threshold of the laser fluence
for the parallel periodic microstructures formation was
higher than that for periodic nanostructures. As the laser
fluence increased from 0.75 to 1.50 J/cm2, suppression of
the parallel periodic microstructures and the periodic
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10µm
E
(a)
10µm
3µm 3µm
10µm
(b) (c)
(f)
3µm
(e)(d)
Fig. 2. SEM images of the irradiation area at the laser fluence of 0.25 J/cm2 ((a) and (d)), 0.75 J/cm2 ((b) and (e)) and 1.50 J/cm2 ((c) and (f)). (a)–(c) At low
magnification and (d)–(f) at high magnification.
∝
3µm
E
(a)
(c1)
(d1)
(d2)
(e1)
(f2)
(f1)
3µm
3µm
3µm 3µm
3µm
(b) (c)
(f)(e)(d)
Fig. 3. Microstructures produced on the titanium plate at the laser fluence of 0.75 J/cm2 for (a) 10, (b) 25, (c) 50, (d) 70, (e) 90 and (f) 110 pulses.
M. Tsukamoto et al. / Vacuum 80 (2006) 1346–13501348
nanostructures formations might be caused. The suppres-
sion mechanisms should be investigated by analyzing the
conditions of the Ti surface shown in Fig. 2(f).
Microstructures produced in the center region of the
irradiation area at 0.75 J/cm2 for 10, 25, 50, 70, 90 and
110 pulses were shown in Figs. 3(a)–(f), respectively. As
Fig. 3(b) shows, the parallel periodic microstructures were
clearly observed for 25 pulses as compared with those for
10 pulses shown in Fig. 3(a). For 10 and 25 pulses, the
periodic nanostructures were superimposed on the parallel
periodic microstructures as shown in Figs. 3(a) and (b). For
50 pulses, as Fig. 3(c) shows, the periodic nanostructures
were not observed on the hill of the parallel periodic
microstructures. Small spheres (microdots) were locally
generated on the hill as indicated with an arrow (c1) in
Fig. 3(c). For 70 pulses, as Fig. 3(d) also shows, hills
between the microdots formed on the parallel periodic
microstructures were etched. Local portions indicated with
arrows (d1) and (d2) in Fig. 3(d) suggested that a microdot
was joined with a neighbor microdot. For 90 pulses, shape
of local portion indicated with an arrow (e1) in Fig. 3(e)
suggested that a hill of the parallel periodic microstructures
was bonded with a neighbor hill of that and this bond-
ing was induced by the joining of microdots such as
local portions indicated with (d1) and (d2) in Fig. 3(d). In
Fig. 3(f), the parallel periodic microstructures were still
observed for 110 pulses. However, as indicated with an
arrow (f1) in Fig. 3(f), etching of the hills between the
microdots was carried on throughout the bonding of the
hills shown with an arrow (e1) in Fig. 3(e). By this process,
height of the microdot from the bottom of the etching
region was increased as compared with that for 70 pulses
shown in Fig. 3(d). Thus, the hills of the parallel periodic
microstructures for 25 pulses were varied to the hills with
strong spatial modulations for 110 pulses.
The period of the parallel periodic microstructures as a
function of the number of laser pulses is shown in Fig. 4.
As shown in Fig. 4, the period was gradually increased in
the range of 10–70 pulses and increased in the range of
70–110 pulses as the number of pulse increased. In the
range of 70–110 pulses, observation of the microdots and
the hills in Figs. 3(d)–(f) indicated that the increasing of the
period was caused due to the bonding of the microdots and
the hill of the parallel periodic microstructures.
Distance between the microdots along the hill of periodic
microstructures as a function of the number of laser pulses
is shown in Fig. 5. As Fig. 5 shows, the distance was
increased in the range of 50–110 pulses. In the range of
10–25 pulses, microdots were not produced as shown in
Figs. 3(a) and (b). Observation of the microdots and the
hills in Figs. 3(c)–(f) indicated that the increasing of the
distance shown in Fig. 5 was caused due to the bonding of
the microdots and the hill of the parallel periodic
microstructures.
As Figs. 2(b) and (e) show, when the parallel periodic
microstructures were produced, the periodic nanostruc-
tures were also created and the parallel periodic micro-
structures were always oriented to the direction
perpendicular to the periodic nanostructures’ direction.
Thus, the periodic nanostructures might cause the parallel
periodic microstructures formation. In this case, as in the
periodic nanostructures creation [11–14], the parallel
periodic microstructures (angular frequency: oppm) were
formed by an intensity modulation (oim), which arose from
the interaction of the laser and its scattered wave (oL) with
a surface wave (osw). The surface wave might be induced
by the periodic nanostructures (opn). Then, the oppm is
given by oppm ¼ oim ¼ osw2oL ¼ opn2oL. Since oppm,
opn and oL are oppm ¼ 2pc=lppm, opn ¼ 2pc=lpn and
oL ¼ 2pc=lL, lpn is lpn ¼ lLlppm=ðlL þ lppmÞ, where c,
lppm and lpn are light velocity, the wavelengths (periods) of
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0
1
2
3
4
5
0 20 40 60 80 100 120
P
er
io
d
of
pa
ra
lle
l p
er
io
di
c
m
ic
ro
st
ru
ct
ur
es
[µ
m
]
Number of laser pulses
Fig. 4. Period of parallel periodic microstructures as a function of number
of laser pulses.
0
5
3
2
1
4
0 20 40 60 10080 120
Number of laser pulse
D
is
ta
nc
e
be
tw
ee
n
th
e
m
ic
ro
do
ts
al
on
g
th
e
hi
ll
of
p
er
io
di
c
m
ic
ro
st
ru
ct
ur
es
[µ
m
]
6
7
8
Fig. 5. Distance between the microdots along the hill of periodic
microstructures as a function of the number of laser pulses.
M. Tsukamoto et al. / Vacuum 80 (2006) 1346–1350 1349
the parallel periodic microstructures and the periodic
nanostructures, respectively. The period of the parallel
periodic microstructures, lppm, was in the range of
1.5–2.4 mm at 10 pulses as shown in Fig. 4. Then, lpn is
522–600 nm, which was derived from lpn ¼ lLlppm=ðlL þ
lppmÞ at lL ¼ 800 nm and lppm ¼ 1:522:4mm. The lpn is
shorter than 700 nm, the period of the periodic nanos-
tructures shown in Fig. 2(e). Thus, the energy conservation
law of the laser, the parallel periodic microstructures and
the surface wave has not yet been satisfied. When the
energy conservation law of them is satisfied, matching
conditions of the wave vectors of them must be satisfied to
propose the mechanism described above to interpret the
parallel periodic microstructures formation. Formation
mechanisms of microdots and spatial modulations on the
hills of the parallel periodic microstructures also have not
yet been elucidated. It is intended to report more detailed
analysis of the parallel periodic microstructures, microdots
and spatial modulations on the hills separately since
additional measurements and theory on the laser interac-
tion with surface microstructures formed on the Ti plate
are required.
4. Conclusion
We investigated the femtosecond laser-produced micro-
structures on the Ti plate surface. The parallel periodic
microstructures were observed in the range of over
0.25–1.5 J/cm2 for 10 pulses, which lied parallel to the
laser electric polarization field vector. For 50 pulses at
0.75 J/cm2, the microdots were generated on the hills of the
parallel periodic microstructures. For 70 pulses at 0.75 J/
cm2, initial spatial modulations on the hills were created
with the microdots formation. In the range of 70–110
pulses for 0.75 J/cm2, the period of the parallel periodic
microstructures was increased due to the bonding of the
hills and the parallel periodic microstructures were varied
to those with strong spatial modulations for 110 pulses.
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