New FRET plugin announcement
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Hi,
Our new sensitized emission ratiometric FRET plugin for ImageJ is available at: http://www.biophys.dote.hu/rifret/ Features: - FRET calculation based on donor, acceptor, and sensitized emission images with all the necessary corrections - three different calibration methods for various fluorophore constellations - handles image stacks - semi-automatic processing for larger data sets - automatic unbundling of lsm format image sets - registration, filtering - freely available - support and additional features on request Best regards, Janos |
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I have been requested to provide a non-gaussian profile for the laser
output on our Ti:Sapphire laser that is used on our custom built multiphoton devices. This profile--apparently more of an annulus--works best for obtaining SHG on nano-sized features introduced onto metal surfaces. The profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). Since I am hoping to add an additional laser to the system, my desire is to provide a laser system in which either the TEM00 or TEM10 profile can be chosen, if this is even a possibility. Barring that, can the TEM10 profile be used on standard biological samples for both SHG and standard excitation of fluorophores, or will the profile affect the results (e.g., will resolution or some other characteristic change)? If anyone has had experience with the TEM10 profile, I'd appreciate feedback! Jerry Sedgewick Program Director Biomedical Image Processing Lab University of Minnesota |
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Isn't TEM10 a double-lobed thing? I think shearing will generate that mode.
Craig On Thu, Aug 20, 2009 at 1:01 PM, Jerry (Gerald) Sedgewick<[hidden email]> wrote: > I have been requested to provide a non-gaussian profile for the laser output > on our Ti:Sapphire laser that is used on our custom built multiphoton > devices. This profile--apparently more of an annulus--works best for > obtaining SHG on nano-sized features introduced onto metal surfaces. The > profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). > Since I am hoping to add an additional laser to the system, my desire is to > provide a laser system in which either the TEM00 or TEM10 profile can be > chosen, if this is even a possibility. > Barring that, can the TEM10 profile be used on standard biological samples > for both SHG and standard excitation of fluorophores, or will the profile > affect the results (e.g., will resolution or some other characteristic > change)? > > If anyone has had experience with the TEM10 profile, I'd appreciate > feedback! > > Jerry Sedgewick > Program Director > Biomedical Image Processing Lab > University of Minnesota > |
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In reply to this post by Jerry (Gerald) Sedgewick
The profile that you describe is not TEM01 (a double D pattern) but TEM01* or the donut mode. It is a superposition of TEM10 and TEM01. It can be linearly polarized (vertical or horizontal) or radially polarized or tangentially polarized.
Lauren M. Peterson, PhD Lead Physicist - Photonics Michigan Research & Development Center General Dynamics - Advanced Information Systems; Integrated Space Systems 1200 Joe Hall Dr., P.O. Box 990 Ypsilanti, MI 48197 734-480-5303 -480-5252 FAX ISS-SIS-ATD-EPA [hidden email] Demetrius Ypsilanti fought in the Greek war for independence against the Ottoman Empire and led the culminating Battle of Petra in 1829. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Jerry (Gerald) Sedgewick Sent: Thursday, August 20, 2009 3:01 PM To: [hidden email] Subject: Re: laser profiles I have been requested to provide a non-gaussian profile for the laser output on our Ti:Sapphire laser that is used on our custom built multiphoton devices. This profile--apparently more of an annulus--works best for obtaining SHG on nano-sized features introduced onto metal surfaces. The profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). Since I am hoping to add an additional laser to the system, my desire is to provide a laser system in which either the TEM00 or TEM10 profile can be chosen, if this is even a possibility. Barring that, can the TEM10 profile be used on standard biological samples for both SHG and standard excitation of fluorophores, or will the profile affect the results (e.g., will resolution or some other characteristic change)? If anyone has had experience with the TEM10 profile, I'd appreciate feedback! Jerry Sedgewick Program Director Biomedical Image Processing Lab University of Minnesota |
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In reply to this post by Craig Brideau
The annular mode I think being referring to is a TEM01 (Laguerre-Gaussian) mode. This mode solves the propagation equation when using cylindrical coordinates. It is often referred to as a doughnut or bagel mode. These modes have a profile similar to a Bessel beam. In fact, a Bessel beam can be created by passing this mode through an axicon. Bessel beams are known to be non-diffracting (at least a perfect Bessel beam). This beam profile can be used to greatly enhance the lateral resolution of an imaging system. I presume this is the reason you are interested in the mode. The tighter focusing will allow higher SHG signal by improving the phase matching. This mode profile should not have any negative effects on SHG or two-photon fluorescence in biological samples. It may actually help generate higher signals and improve lateral resolution. Of course, the tighter focusing may require you to reduce the on sample power to reduce nonlinear photodamage. As far as I know the drawback to these beams is a reduction in the axial resolution. If I remember correctly, this results from the axial component of the polarization vector in the mode as it is focused under high NA. To make designing a laser a little bit easier since I believe that the Laguerre-Gaussian modes are a little bit more difficult to obtain than the usual Hermite-Gaussian mode profiles (misalignment, dirt and strain on optical surfaces tends to push lasers into propagation modes solved by rectangular coordinates), can you use a Gaussian TEM00 mode passed through an axicon creating a circular beam profile?.
Regards, Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau Sent: Thursday, August 20, 2009 3:29 PM To: [hidden email] Subject: Re: laser profiles Isn't TEM10 a double-lobed thing? I think shearing will generate that mode. Craig On Thu, Aug 20, 2009 at 1:01 PM, Jerry (Gerald) Sedgewick<[hidden email]> wrote: > I have been requested to provide a non-gaussian profile for the laser output > on our Ti:Sapphire laser that is used on our custom built multiphoton > devices. This profile--apparently more of an annulus--works best for > obtaining SHG on nano-sized features introduced onto metal surfaces. The > profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). > Since I am hoping to add an additional laser to the system, my desire is to > provide a laser system in which either the TEM00 or TEM10 profile can be > chosen, if this is even a possibility. > Barring that, can the TEM10 profile be used on standard biological samples > for both SHG and standard excitation of fluorophores, or will the profile > affect the results (e.g., will resolution or some other characteristic > change)? > > If anyone has had experience with the TEM10 profile, I'd appreciate > feedback! > > Jerry Sedgewick > Program Director > Biomedical Image Processing Lab > University of Minnesota > |
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A Gaussian beam laser often has an internal aperture to restrict higher modes leaving only the lowest order TEM00. If this is the case for your Ti:saph laser, the donut mode can often be obtained by simply replacing the aperture with one having a larger hole. You should get considerably greater laser output power but the beam divergence will also be significantly larger. Greater power can give you more SHG but the greater divergence will produce a larger focal spot which could reduce SHG. It depends on which dominates.
I don't have much experience with axicon lenses but I am skeptical about how effective it would be. The axicon may indeed produce a donut shaped beam in the near field but in the far field and therefore the focus of your lens, you may lose your donut and you may no longer be close to the diffraction limit making the SHG much worse. Lauren M. Peterson, PhD Lead Physicist - Photonics Michigan Research & Development Center General Dynamics - Advanced Information Systems; Integrated Space Systems 1200 Joe Hall Dr., P.O. Box 990 Ypsilanti, MI 48197 734-480-5303 -480-5252 FAX ISS-SIS-ATD-EPA [hidden email] Demetrius Ypsilanti fought in the Greek war for independence against the Ottoman Empire and led the culminating Battle of Petra in 1829. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Adam Larson Sent: Thursday, August 20, 2009 4:05 PM To: [hidden email] Subject: Re: laser profiles The annular mode I think being referring to is a TEM01 (Laguerre-Gaussian) mode. This mode solves the propagation equation when using cylindrical coordinates. It is often referred to as a doughnut or bagel mode. These modes have a profile similar to a Bessel beam. In fact, a Bessel beam can be created by passing this mode through an axicon. Bessel beams are known to be non-diffracting (at least a perfect Bessel beam). This beam profile can be used to greatly enhance the lateral resolution of an imaging system. I presume this is the reason you are interested in the mode. The tighter focusing will allow higher SHG signal by improving the phase matching. This mode profile should not have any negative effects on SHG or two-photon fluorescence in biological samples. It may actually help generate higher signals and improve lateral resolution. Of course, the tighter focusing may require you to reduce the on sample power to reduce nonlinear photodamage. As far as I know the drawback to these beams is a reduction in the axial resolution. If I remember correctly, this results from the axial component of the polarization vector in the mode as it is focused under high NA. To make designing a laser a little bit easier since I believe that the Laguerre-Gaussian modes are a little bit more difficult to obtain than the usual Hermite-Gaussian mode profiles (misalignment, dirt and strain on optical surfaces tends to push lasers into propagation modes solved by rectangular coordinates), can you use a Gaussian TEM00 mode passed through an axicon creating a circular beam profile?. Regards, Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau Sent: Thursday, August 20, 2009 3:29 PM To: [hidden email] Subject: Re: laser profiles Isn't TEM10 a double-lobed thing? I think shearing will generate that mode. Craig On Thu, Aug 20, 2009 at 1:01 PM, Jerry (Gerald) Sedgewick<[hidden email]> wrote: > I have been requested to provide a non-gaussian profile for the laser output > on our Ti:Sapphire laser that is used on our custom built multiphoton > devices. This profile--apparently more of an annulus--works best for > obtaining SHG on nano-sized features introduced onto metal surfaces. The > profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). > Since I am hoping to add an additional laser to the system, my desire is to > provide a laser system in which either the TEM00 or TEM10 profile can be > chosen, if this is even a possibility. > Barring that, can the TEM10 profile be used on standard biological samples > for both SHG and standard excitation of fluorophores, or will the profile > affect the results (e.g., will resolution or some other characteristic > change)? > > If anyone has had experience with the TEM10 profile, I'd appreciate > feedback! > > Jerry Sedgewick > Program Director > Biomedical Image Processing Lab > University of Minnesota > |
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Yes, I agree that would be a way to obtain a donut mode in a CW laser. If he is soft aperture Kerr lens modelocking his laser there will not be an aperture in the cavity. A Gaussian mode is favored here because you want to optimize the overlap of the pump, which has a Gaussian mode profile, and the Ti:S beam. Poor overlap or poor spatial mode overlap will result in less power, CW breakthrough, and a reduction in pulse spectrum. If the laser is hard aperture Kerr lens modelocked the slit will block most higher order modes from lasing. A slit opened wide enough to allow higher order cavity modes to propagate will likely not allow for modelocking. I am less familiar with modelocking using a saturable absorber but I believe the increased diameter of the higher order mode will not reach saturation and therefore does not see a high enough gain to propagate. That is why I am not sure it is relatively straight forward to create this mode.
Below are two papers which talk about annular illumination in laser scanning microscopes. E.J. Botcherby, R. Juskaitis, T. Wilson, "Scanning two photon fluorescence microscopy with extended depth of field" Optics Communications 268 (2006) 253-260 Colin J. R. Sheppard and Amarjyoti Choudhury, "Annular Pupils, Radial Polarization, and Superresolution," Appl. Opt. 43, 4322-4327 (2004) Regards Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Peterson, Lauren M. Sent: Thursday, August 20, 2009 4:20 PM To: [hidden email] Subject: Re: laser profiles A Gaussian beam laser often has an internal aperture to restrict higher modes leaving only the lowest order TEM00. If this is the case for your Ti:saph laser, the donut mode can often be obtained by simply replacing the aperture with one having a larger hole. You should get considerably greater laser output power but the beam divergence will also be significantly larger. Greater power can give you more SHG but the greater divergence will produce a larger focal spot which could reduce SHG. It depends on which dominates. I don't have much experience with axicon lenses but I am skeptical about how effective it would be. The axicon may indeed produce a donut shaped beam in the near field but in the far field and therefore the focus of your lens, you may lose your donut and you may no longer be close to the diffraction limit making the SHG much worse. Lauren M. Peterson, PhD Lead Physicist - Photonics Michigan Research & Development Center General Dynamics - Advanced Information Systems; Integrated Space Systems 1200 Joe Hall Dr., P.O. Box 990 Ypsilanti, MI 48197 734-480-5303 -480-5252 FAX ISS-SIS-ATD-EPA [hidden email] Demetrius Ypsilanti fought in the Greek war for independence against the Ottoman Empire and led the culminating Battle of Petra in 1829. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Adam Larson Sent: Thursday, August 20, 2009 4:05 PM To: [hidden email] Subject: Re: laser profiles The annular mode I think being referring to is a TEM01 (Laguerre-Gaussian) mode. This mode solves the propagation equation when using cylindrical coordinates. It is often referred to as a doughnut or bagel mode. These modes have a profile similar to a Bessel beam. In fact, a Bessel beam can be created by passing this mode through an axicon. Bessel beams are known to be non-diffracting (at least a perfect Bessel beam). This beam profile can be used to greatly enhance the lateral resolution of an imaging system. I presume this is the reason you are interested in the mode. The tighter focusing will allow higher SHG signal by improving the phase matching. This mode profile should not have any negative effects on SHG or two-photon fluorescence in biological samples. It may actually help generate higher signals and improve lateral resolution. Of course, the tighter focusing may require you to reduce the on sample power to reduce nonlinear photodamage. As far as I know the drawback to these beams is a reduction in the axial resolution. If I remember correctly, this results from the axial component of the polarization vector in the mode as it is focused under high NA. To make designing a laser a little bit easier since I believe that the Laguerre-Gaussian modes are a little bit more difficult to obtain than the usual Hermite-Gaussian mode profiles (misalignment, dirt and strain on optical surfaces tends to push lasers into propagation modes solved by rectangular coordinates), can you use a Gaussian TEM00 mode passed through an axicon creating a circular beam profile?. Regards, Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau Sent: Thursday, August 20, 2009 3:29 PM To: [hidden email] Subject: Re: laser profiles Isn't TEM10 a double-lobed thing? I think shearing will generate that mode. Craig On Thu, Aug 20, 2009 at 1:01 PM, Jerry (Gerald) Sedgewick<[hidden email]> wrote: > I have been requested to provide a non-gaussian profile for the laser output > on our Ti:Sapphire laser that is used on our custom built multiphoton > devices. This profile--apparently more of an annulus--works best for > obtaining SHG on nano-sized features introduced onto metal surfaces. The > profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). > Since I am hoping to add an additional laser to the system, my desire is to > provide a laser system in which either the TEM00 or TEM10 profile can be > chosen, if this is even a possibility. > Barring that, can the TEM10 profile be used on standard biological samples > for both SHG and standard excitation of fluorophores, or will the profile > affect the results (e.g., will resolution or some other characteristic > change)? > > If anyone has had experience with the TEM10 profile, I'd appreciate > feedback! > > Jerry Sedgewick > Program Director > Biomedical Image Processing Lab > University of Minnesota > |
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There several methods for producing a doughnut beam from a TEM00 laser output - look in the STED literature for examples since that it fundamental to STED.
Steve Baer will be presenting a totally new way of doing this at the 2009 Super and High Resolution Imaging Conference in Lipica, Slovenia (just over the border from Trieste, Italy) which gives me the chance to remind everyone that there is still time to register: http://SHRI.TASC.INFM.IT Guy Optical Imaging Techniques in Cell Biology by Guy Cox CRC Press / Taylor & Francis http://www.guycox.com/optical.htm ______________________________________________ Associate Professor Guy Cox, MA, DPhil(Oxon) Electron Microscope Unit, Madsen Building F09, University of Sydney, NSW 2006 ______________________________________________ Phone +61 2 9351 3176 Fax +61 2 9351 7682 Mobile 0413 281 861 ______________________________________________ http://www.guycox.net -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Adam Larson Sent: Friday, 21 August 2009 7:08 AM To: [hidden email] Subject: Re: laser profiles Yes, I agree that would be a way to obtain a donut mode in a CW laser. If he is soft aperture Kerr lens modelocking his laser there will not be an aperture in the cavity. A Gaussian mode is favored here because you want to optimize the overlap of the pump, which has a Gaussian mode profile, and the Ti:S beam. Poor overlap or poor spatial mode overlap will result in less power, CW breakthrough, and a reduction in pulse spectrum. If the laser is hard aperture Kerr lens modelocked the slit will block most higher order modes from lasing. A slit opened wide enough to allow higher order cavity modes to propagate will likely not allow for modelocking. I am less familiar with modelocking using a saturable absorber but I believe the increased diameter of the higher order mode will not reach saturation and therefore does not see a high enough gain to propagate. That is why I am not sure it is relatively straight forward to create this mode. Below are two papers which talk about annular illumination in laser scanning microscopes. E.J. Botcherby, R. Juskaitis, T. Wilson, "Scanning two photon fluorescence microscopy with extended depth of field" Optics Communications 268 (2006) 253-260 Colin J. R. Sheppard and Amarjyoti Choudhury, "Annular Pupils, Radial Polarization, and Superresolution," Appl. Opt. 43, 4322-4327 (2004) Regards Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Peterson, Lauren M. Sent: Thursday, August 20, 2009 4:20 PM To: [hidden email] Subject: Re: laser profiles A Gaussian beam laser often has an internal aperture to restrict higher modes leaving only the lowest order TEM00. If this is the case for your Ti:saph laser, the donut mode can often be obtained by simply replacing the aperture with one having a larger hole. You should get considerably greater laser output power but the beam divergence will also be significantly larger. Greater power can give you more SHG but the greater divergence will produce a larger focal spot which could reduce SHG. It depends on which dominates. I don't have much experience with axicon lenses but I am skeptical about how effective it would be. The axicon may indeed produce a donut shaped beam in the near field but in the far field and therefore the focus of your lens, you may lose your donut and you may no longer be close to the diffraction limit making the SHG much worse. Lauren M. Peterson, PhD Lead Physicist - Photonics Michigan Research & Development Center General Dynamics - Advanced Information Systems; Integrated Space Systems 1200 Joe Hall Dr., P.O. Box 990 Ypsilanti, MI 48197 734-480-5303 -480-5252 FAX ISS-SIS-ATD-EPA [hidden email] Demetrius Ypsilanti fought in the Greek war for independence against the Ottoman Empire and led the culminating Battle of Petra in 1829. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Adam Larson Sent: Thursday, August 20, 2009 4:05 PM To: [hidden email] Subject: Re: laser profiles The annular mode I think being referring to is a TEM01 (Laguerre-Gaussian) mode. This mode solves the propagation equation when using cylindrical coordinates. It is often referred to as a doughnut or bagel mode. These modes have a profile similar to a Bessel beam. In fact, a Bessel beam can be created by passing this mode through an axicon. Bessel beams are known to be non-diffracting (at least a perfect Bessel beam). This beam profile can be used to greatly enhance the lateral resolution of an imaging system. I presume this is the reason you are interested in the mode. The tighter focusing will allow higher SHG signal by improving the phase matching. This mode profile should not have any negative effects on SHG or two-photon fluorescence in biological samples. It may actually help generate higher signals and improve lateral resolution. Of course, the tighter focusing may require you to reduce the on sample power to reduce nonlinear photodamage. As far as I know the drawback to these beams is a reduction in the axial resolution. If I remember correctly, this results from the axial component of the polarization vector in the mode as it is focused under high NA. To make designing a laser a little bit easier since I believe that the Laguerre-Gaussian modes are a little bit more difficult to obtain than the usual Hermite-Gaussian mode profiles (misalignment, dirt and strain on optical surfaces tends to push lasers into propagation modes solved by rectangular coordinates), can you use a Gaussian TEM00 mode passed through an axicon creating a circular beam profile?. Regards, Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau Sent: Thursday, August 20, 2009 3:29 PM To: [hidden email] Subject: Re: laser profiles Isn't TEM10 a double-lobed thing? I think shearing will generate that mode. Craig On Thu, Aug 20, 2009 at 1:01 PM, Jerry (Gerald) Sedgewick<[hidden email]> wrote: > I have been requested to provide a non-gaussian profile for the laser > output on our Ti:Sapphire laser that is used on our custom built > multiphoton devices. This profile--apparently more of an > annulus--works best for obtaining SHG on nano-sized features > introduced onto metal surfaces. The profile is referred to as TEM10 (versus TEM00, which is a gaussian profile). > Since I am hoping to add an additional laser to the system, my desire > is to provide a laser system in which either the TEM00 or TEM10 > profile can be chosen, if this is even a possibility. > Barring that, can the TEM10 profile be used on standard biological > samples for both SHG and standard excitation of fluorophores, or will > the profile affect the results (e.g., will resolution or some other > characteristic change)? > > If anyone has had experience with the TEM10 profile, I'd appreciate > feedback! > > Jerry Sedgewick > Program Director > Biomedical Image Processing Lab > University of Minnesota > |
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In reply to this post by Adam Larson
This is a bit removed from the original topic of donut modes, but since Bessel beams were brought up: I'm wondering if there's a sheet-like analog of a Bessel beam, i.e. a way of focusing a Gaussian beam along one dimension only, creating a line (or long ellipse) such that along the short axis the beam is non-diffracting. Another way to ask: An axicon converts a Gaussian beam into a non-diffracting Bessel beam. A cylindrical lens converts a Gaussian beam into a line. "X" converts a Gaussian beam into a non-diffracting line. What is "X"? (This is, in fact, relevant for a sheet-illumination setup I plan to build, so any thoughts would be
appreciated!) best wishes, Raghu From: Adam Larson <[hidden email]> To: [hidden email] Sent: Thursday, August 20, 2009 1:04:54 PM Subject: Re: laser profiles The annular mode I think being referring to is a TEM01 (Laguerre-Gaussian) mode. This mode solves the propagation equation when using cylindrical coordinates. It is often referred to as a doughnut or bagel mode. These modes have a profile similar to a Bessel beam. In fact, a Bessel beam can be created by passing this mode through an axicon. Bessel beams are known to be non-diffracting (at least a perfect Bessel beam). This beam profile can be used to greatly enhance the lateral resolution of an imaging system. [deleted]... Regards, Adam M. Larson, Ph.D. Advanced Imaging Group 435 Route 206 Newton, NJ 07860 Tel: (973)300-4497 THORLABS Inc. -----Original Message----- From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau Sent: Thursday, August 20, 2009 3:29 PM To: [hidden email] Subject: Re: laser profiles Isn't TEM10 a double-lobed thing? I think shearing will generate that mode. Craig -- Raghuveer Parthasarathy [hidden email] Assistant Professor Department of Physics 1274 University of Oregon Eugene, OR 97403-1274 http://physics.uoregon.edu/~raghu/ |
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Dear Raghu, It is probably the best to scan the Gaussian beam to generate a
line, but I guess you might use a barrel lens to enter a collimated line into
an axicon. Florian
Fahrbach & Alexander Rohrbach from Freiburg university have presented an
apparatus that uses a
spatial light modulator (SLM) instead of an axicon to generate such a Bessel beam
light sheet illumination. http://www.focusonmicroscopy.org/2009/PDF/281_Fahrbach.pdf Cheers, jens From: Confocal Microscopy
List [mailto:[hidden email]] On Behalf Of Raghu
Parthasarathy
This is a bit removed from the original topic of donut modes, but since Bessel
beams were brought up: I'm wondering if there's a sheet-like analog of a
Bessel beam, i.e. a way of focusing a Gaussian beam along one dimension
only, creating a line (or long ellipse) such that along the short axis the beam
is non-diffracting. Another way to ask: An axicon converts a
Gaussian beam into a non-diffracting Bessel beam. A cylindrical lens
converts a Gaussian beam into a line. "X" converts a Gaussian
beam into a non-diffracting line. What is "X"? (This is,
in fact, relevant for a sheet-illumination setup I plan to build, so any
thoughts would be appreciated!) From: Adam Larson
<[hidden email]> |
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