FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Science and Technology » Physics » Acoustics
non contact measurement
Post new topic   Reply to topic Page 1 of 1 [14 Posts] View previous topic :: View next topic
Author Message
ri
science forum beginner


Joined: 04 May 2006
Posts: 5

PostPosted: Thu May 11, 2006 12:38 am    Post subject: Re: non contact measurement Reply with quote

"GregS" <szekeres@pitt.edu> wrote in message
news:e3ssbr$3om$3@usenet01.srv.cis.pitt.edu...
Quote:
In article <e3sqb1$3om$1@usenet01.srv.cis.pitt.edu>, szekeres@pitt.edu
(GregS) wrote:
In article <44615277_2@news.tm.net.my>, "ri" <rupsyco@tm.net.my> wrote:

"GregS" <szekeres@pitt.edu> wrote in message
news:e3nfce$p5l$2@usenet01.srv.cis.pitt.edu...
In article <e3j4ck$shm$1@ss408.t-com.hr>, "Neky Lyk" <ned@m.mejl
wrote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you
see
breakup modes, but very simple ones, to focus on a cone vibrating
for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact
measurement of vibration of which I am aware. Both systems measure
displacementMT and are therefore frequency limited. One is the I
photonic
sensor, for which the vibrating surface needs to be reflective to
light,
which can be accomplished by bonding a very thin reflective piece
of
aluminum foil at the measurement location. The other is a
capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly
sense
the
"loud" signal of the driver...


On the cover of 6/1988 Speaker Builder magazine is a device hovering
over
the cone of an 8 inch driver, which is a Panasonic mic element.It has a
lever whereby the position
can be changed. This was for developing a map of the driver being
driven.

greg

i think there are ways to pre-filter the measured frequency. from what
i
saw
you get a cap of some sort that you put on the mic capsule and it
shriks
the
working/recieved freq. range.


I am in Malaysia, I don't know how to get that specific release of
Speaker
Builder. is there a link?

if let's say I use infrared, then I shall modulate a high frequency
signal
(40kHz i.e.), and using the FM coming out from doppler effect detect the
signal (does it make sense for a such relatively slow moving part to
cause
any shift in frequency for doppler effect?). Or I could measure the
change
in intensity of the reflected beam. Do you think ultrasounds would do?

The change in intensity should be fine. A little adjustment of angles and
reflectance.

I was thinking, there is probably non-linearity since doubling distance is
going to produce less than 1/2 the light.

greg
But if I'm just seeking the period to retrieve the frequency, it should be

fine, right?

Ric
Back to top
GregS
science forum beginner


Joined: 30 Jun 2005
Posts: 47

PostPosted: Wed May 10, 2006 2:11 pm    Post subject: Re: non contact measurement Reply with quote

In article <e3sqb1$3om$1@usenet01.srv.cis.pitt.edu>, szekeres@pitt.edu (GregS) wrote:
Quote:
In article <44615277_2@news.tm.net.my>, "ri" <rupsyco@tm.net.my> wrote:

"GregS" <szekeres@pitt.edu> wrote in message
news:e3nfce$p5l$2@usenet01.srv.cis.pitt.edu...
In article <e3j4ck$shm$1@ss408.t-com.hr>, "Neky Lyk" <ned@m.mejl> wrote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating
for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact
measurement of vibration of which I am aware. Both systems measure
displacementMT and are therefore frequency limited. One is the I
photonic
sensor, for which the vibrating surface needs to be reflective to
light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly sense
the
"loud" signal of the driver...


On the cover of 6/1988 Speaker Builder magazine is a device hovering over
the cone of an 8 inch driver, which is a Panasonic mic element.It has a
lever whereby the position
can be changed. This was for developing a map of the driver being driven.

greg

i think there are ways to pre-filter the measured frequency. from what i
saw
you get a cap of some sort that you put on the mic capsule and it shriks
the
working/recieved freq. range.


I am in Malaysia, I don't know how to get that specific release of Speaker
Builder. is there a link?

if let's say I use infrared, then I shall modulate a high frequency signal
(40kHz i.e.), and using the FM coming out from doppler effect detect the
signal (does it make sense for a such relatively slow moving part to cause
any shift in frequency for doppler effect?). Or I could measure the change
in intensity of the reflected beam. Do you think ultrasounds would do?

The change in intensity should be fine. A little adjustment of angles and
reflectance.

I was thinking, there is probably non-linearity since doubling distance is
going to produce less than 1/2 the light.

greg
Back to top
GregS
science forum beginner


Joined: 30 Jun 2005
Posts: 47

PostPosted: Wed May 10, 2006 1:37 pm    Post subject: Re: non contact measurement Reply with quote

In article <44615277_2@news.tm.net.my>, "ri" <rupsyco@tm.net.my> wrote:
Quote:

"GregS" <szekeres@pitt.edu> wrote in message
news:e3nfce$p5l$2@usenet01.srv.cis.pitt.edu...
In article <e3j4ck$shm$1@ss408.t-com.hr>, "Neky Lyk" <ned@m.mejl> wrote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating
for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact
measurement of vibration of which I am aware. Both systems measure
displacementMT and are therefore frequency limited. One is the I
photonic
sensor, for which the vibrating surface needs to be reflective to
light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly sense
the
"loud" signal of the driver...


On the cover of 6/1988 Speaker Builder magazine is a device hovering over
the cone of an 8 inch driver, which is a Panasonic mic element.It has a
lever whereby the position
can be changed. This was for developing a map of the driver being driven.

greg

i think there are ways to pre-filter the measured frequency. from what i
saw
you get a cap of some sort that you put on the mic capsule and it shriks
the
working/recieved freq. range.


I am in Malaysia, I don't know how to get that specific release of Speaker
Builder. is there a link?

if let's say I use infrared, then I shall modulate a high frequency signal
(40kHz i.e.), and using the FM coming out from doppler effect detect the
signal (does it make sense for a such relatively slow moving part to cause
any shift in frequency for doppler effect?). Or I could measure the change
in intensity of the reflected beam. Do you think ultrasounds would do?

The change in intensity should be fine. A little adjustment of angles and
reflectance.

greg
Back to top
ri
science forum beginner


Joined: 04 May 2006
Posts: 5

PostPosted: Wed May 10, 2006 2:39 am    Post subject: Re: non contact measurement Reply with quote

"GregS" <szekeres@pitt.edu> wrote in message
news:e3nfce$p5l$2@usenet01.srv.cis.pitt.edu...
Quote:
In article <e3j4ck$shm$1@ss408.t-com.hr>, "Neky Lyk" <ned@m.mejl> wrote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating
for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact
measurement of vibration of which I am aware. Both systems measure
displacementMT and are therefore frequency limited. One is the I
photonic
sensor, for which the vibrating surface needs to be reflective to
light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly sense
the
"loud" signal of the driver...


On the cover of 6/1988 Speaker Builder magazine is a device hovering over
the cone of an 8 inch driver, which is a Panasonic mic element.It has a
lever whereby the position
can be changed. This was for developing a map of the driver being driven.

greg

i think there are ways to pre-filter the measured frequency. from what i
saw
you get a cap of some sort that you put on the mic capsule and it shriks
the
working/recieved freq. range.


I am in Malaysia, I don't know how to get that specific release of Speaker

Builder. is there a link?

if let's say I use infrared, then I shall modulate a high frequency signal
(40kHz i.e.), and using the FM coming out from doppler effect detect the
signal (does it make sense for a such relatively slow moving part to cause
any shift in frequency for doppler effect?). Or I could measure the change
in intensity of the reflected beam. Do you think ultrasounds would do?
Back to top
GregS
science forum beginner


Joined: 30 Jun 2005
Posts: 47

PostPosted: Mon May 08, 2006 12:59 pm    Post subject: Re: non contact measurement Reply with quote

In article <e3j4ck$shm$1@ss408.t-com.hr>, "Neky Lyk" <ned@m.mejl> wrote:
Quote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI
photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly sense the
"loud" signal of the driver...


On the cover of 6/1988 Speaker Builder magazine is a device hovering over
the cone of an 8 inch driver, which is a Panasonic mic element.It has a lever whereby the position
can be changed. This was for developing a map of the driver being driven.

greg

Quote:
i think there are ways to pre-filter the measured frequency. from what i saw
you get a cap of some sort that you put on the mic capsule and it shriks the
working/recieved freq. range.

Back to top
Neky Lyk
science forum beginner


Joined: 25 Mar 2006
Posts: 15

PostPosted: Sun May 07, 2006 9:19 am    Post subject: Re: non contact measurement Reply with quote

"Neky Lyk" <ned@m.mejl> wrote in message news:e3kd4v$mdj$1@ss408.t-com.hr...

<cut>

Quote:

You really need to get off the drugs.

nah. i like them Smile they help me. you don't wanna see what happens when i
don't :)


*when i don't take them
Back to top
Neky Lyk
science forum beginner


Joined: 25 Mar 2006
Posts: 15

PostPosted: Sun May 07, 2006 9:03 am    Post subject: Re: non contact measurement Reply with quote

"The Ghost" <theghost@hotmail.com> wrote in message
news:8U87g.117427$2g2.61584@fe07.news.easynews.com...
Quote:
"Neky Lyk" <ned@m.mejl> wrote in news:e3j4ck$shm$1@ss408.t-com.hr:


"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up, I guess not as a mic would do, but often to check on
resonance frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you
see breakup modes, but very simple ones, to focus on a cone
vibrating for sympathy and gives you a signal from it's
vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact measurement of vibration of which I am aware. Both
systems measure displacement and are therefore frequency limited.
One is the MTI
photonic
sensor, for which the vibrating surface needs to be reflective to
light, which can be accomplished by bonding a very thin reflective
piece of aluminum foil at the measurement location. The other is a
capacitive probe, for which the vibrating surface needs to be
electrically conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly
sense the "loud" signal of the driver...


i think there are ways to pre-filter the measured frequency. from what
i saw you get a cap of some sort that you put on the mic capsule and
it shriks the working/recieved freq. range.


You really need to get off the drugs.

nah. i like them Smile they help me. you don't wanna see what happens when i
don't Smile
Back to top
TheGhost
science forum addict


Joined: 09 Aug 2005
Posts: 85

PostPosted: Sat May 06, 2006 9:52 pm    Post subject: Re: non contact measurement Reply with quote

"Neky Lyk" <ned@m.mejl> wrote in news:e3j4ck$shm$1@ss408.t-com.hr:

Quote:

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a
pick-up, I guess not as a mic would do, but often to check on
resonance frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you
see breakup modes, but very simple ones, to focus on a cone
vibrating for sympathy and gives you a signal from it's
vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making
non-contact measurement of vibration of which I am aware. Both
systems measure displacement and are therefore frequency limited.
One is the MTI
photonic
sensor, for which the vibrating surface needs to be reflective to
light, which can be accomplished by bonding a very thin reflective
piece of aluminum foil at the measurement location. The other is a
capacitive probe, for which the vibrating surface needs to be
electrically conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work
without much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly
sense the "loud" signal of the driver...


i think there are ways to pre-filter the measured frequency. from what
i saw you get a cap of some sort that you put on the mic capsule and
it shriks the working/recieved freq. range.


You really need to get off the drugs.
Back to top
Neky Lyk
science forum beginner


Joined: 25 Mar 2006
Posts: 15

PostPosted: Sat May 06, 2006 9:27 pm    Post subject: Re: non contact measurement Reply with quote

"ri" <rupsyco@tm.net.my> wrote in message
news:445ad5b6$1_2@news.tm.net.my...
Quote:
"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI
photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the
passive
radiator of a subwoofer, then a mic, even if nearby, will mainly sense the
"loud" signal of the driver...


i think there are ways to pre-filter the measured frequency. from what i saw
you get a cap of some sort that you put on the mic capsule and it shriks the
working/recieved freq. range.
Back to top
ri
science forum beginner


Joined: 04 May 2006
Posts: 5

PostPosted: Fri May 05, 2006 4:32 am    Post subject: Re: non contact measurement Reply with quote

"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
Quote:
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
but lets say I want to pickup the signal of a resonant body like the passive

radiator of a subwoofer, then a mic, even if nearby, will mainly sense the
"loud" signal of the driver...
Back to top
Neky Lyk
science forum beginner


Joined: 25 Mar 2006
Posts: 15

PostPosted: Wed Apr 19, 2006 6:31 pm    Post subject: Re: non contact measurement Reply with quote

"GregS" <szekeres@pitt.edu> wrote in message
news:e25bv5$lgq$2@usenet01.srv.cis.pitt.edu...
Quote:
In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost
theghost@hotmail.com> wrote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI
photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically
conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge

what's expensive? Smile it's a very relative term.
i suppose you could use a bruel&kjaer mic, model 4193 if i'm correct.
infrasound measurement. pro equipment.
it's _VERY_ expensive... of course 4 my pocket. don't know about yours Smile
Back to top
GregS
science forum beginner


Joined: 30 Jun 2005
Posts: 47

PostPosted: Wed Apr 19, 2006 12:54 pm    Post subject: Re: non contact measurement Reply with quote

In article <HZg1g.3800$4P2.3574@fe03.news.easynews.com>, The Ghost <theghost@hotmail.com> wrote:
Quote:
"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically conductive,
which can be accomplished by spraying it with a conductive paint.

A simple IR emitter detector mounted together will tend to work without
much concern with reflectance.
A small microphone capsule held close to the surface
has also been used.

grge
Back to top
TheGhost
science forum addict


Joined: 09 Aug 2005
Posts: 85

PostPosted: Wed Apr 19, 2006 2:09 am    Post subject: Re: non contact measurement Reply with quote

"Riccardo Balistrerri" <riccardo.balistreri@poste.it> wrote in
news:44458800$1_1@news.tm.net.my:

Quote:
Dear All,

I've seen vibrations measurement systems that use laser as a pick-up,
I guess not as a mic would do, but often to check on resonance
frequencies of cones i.e.

I'm not talking about the very expensive systems that lets you see
breakup modes, but very simple ones, to focus on a cone vibrating for
sympathy and gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.


There are only two relatively inexpensive systems for making non-contact
measurement of vibration of which I am aware. Both systems measure
displacement and are therefore frequency limited. One is the MTI photonic
sensor, for which the vibrating surface needs to be reflective to light,
which can be accomplished by bonding a very thin reflective piece of
aluminum foil at the measurement location. The other is a capacitive
probe, for which the vibrating surface needs to be electrically conductive,
which can be accomplished by spraying it with a conductive paint.
Back to top
Riccardo Balistrerri
science forum beginner


Joined: 19 Apr 2006
Posts: 11

PostPosted: Wed Apr 19, 2006 12:44 am    Post subject: non contact measurement Reply with quote

Dear All,

I've seen vibrations measurement systems that use laser as a pick-up, I
guess not as a mic would do, but often to check on resonance frequencies of
cones i.e.

I'm not talking about the very expensive systems that lets you see breakup
modes, but very simple ones, to focus on a cone vibrating for sympathy and
gives you a signal from it's vibrations.

Anybody can tell me where to get them, and how do they work?

Thanks,
R.
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 1 of 1 [14 Posts] View previous topic :: View next topic
The time now is Thu Jun 29, 2017 7:15 am | All times are GMT
Forum index » Science and Technology » Physics » Acoustics
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts Fluoride measurement: ISE vs. IC liujx7@yahoo.com Chem 0 Fri Jul 21, 2006 1:53 pm
No new posts Fluoride measurement: ISE vs. IC liujx7@yahoo.com Electrochem 2 Fri Jul 21, 2006 4:44 am
No new posts Fluoride measurement: ISE vs. IC liujx7@yahoo.com Analytical 0 Fri Jul 21, 2006 4:24 am
No new posts Fuzzy Inference System (FIS) Based Decision-Making Algori... amizo1@gmail.com Mechanics 0 Fri Jul 14, 2006 7:26 pm
No new posts Qualitative measurement of ion content Jay Electrochem 0 Thu Jul 13, 2006 12:51 am

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Electronics forum |  Medicine forum |  Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums  |  send newsletters
 


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.1658s ][ Queries: 20 (0.1337s) ][ GZIP on - Debug on ]