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Das S, Liang YC, Tanaka S, Ozeki Y, Kao FJ. Synchronized subharmonic modulation in stimulated emission microscopy. OPTICS EXPRESS 2019; 27:27159-27167. [PMID: 31674582 DOI: 10.1364/oe.27.027159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
In this work, we have demonstrated a stimulated emission (SE)-based pump-probe microscopy with subharmonic fast gate synchronization, which allows over an order of magnitude improvement in signal-to-noise ratio. Critically, the alternative way of modulation is implemented with the highest possible frequency that follows the lasers' repetition rate. Its working is based on a homemade frequency divider that divides the repetition frequency (76 MHz) of the Ti:sapphire (probe) laser to half of the repetition frequency, 38 MHz, which is used to synchronously drive the pump laser and to provide the reference signal for the ensuing lock-in detection. In this way, SE can be detected with sensitivity reaching the theoretical (shot noise) limits, with a much lower time constant (0.1 ms) for faster image acquisition.
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Dake F, Hayashi S. High-resolution nonlinear fluorescence microscopy using repetitive stimulated transition based on the saturation of stimulated emission implemented with two-color continuous-wave lasers. OPTICS LETTERS 2019; 44:3402-3405. [PMID: 31259971 DOI: 10.1364/ol.44.003402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 06/07/2019] [Indexed: 06/09/2023]
Abstract
High-resolution nonlinear fluorescence (NF) microscopy that utilizes repetitive stimulated transition due to the saturation of stimulated emission caused by two-color continuous-wave lasers was developed. The resulting NF signal, detected via the lock-in technique, is produced by the multiplicative combination of incident beams, which results in an improvement of the optical resolution. The proposed method is demonstrated to have a three-dimensional optical resolution superior to that of conventional NF microscopy. The results of biological imaging reveal the feasibility and superiority of the proposed method.
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Seto K, Yamada H, Kobayashi T, Tokunaga E. Demonstration of wavelength-scan-free action spectroscopy in pump/probe measurement with supercontinuum pump light. OPTICS EXPRESS 2019; 27:6976-6995. [PMID: 30876272 DOI: 10.1364/oe.27.006976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/10/2019] [Indexed: 06/09/2023]
Abstract
We devise and introduce the principle of wavelength-scan-free spectroscopy for the pump light in pump/probe measurement (action spectroscopy) using supercontinuum light; we demonstrate its implementation by measuring transmission spectra. We use the supercontinuum light noise as a code in order to discriminate wavelength. We extract the stimulation at the desired wavelength by correlating the noise at that wavelength observed separately and the observed total stimulation carried by the probe light. The wavelength-scan-free spectroscopy is enabled with a simultaneous procedure for multiple wavelengths.
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Miyazaki J, Kawasumi K, Kobayashi T. Frequency domain approach for time-resolved pump-probe microscopy using intensity modulated laser diodes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:093703. [PMID: 25273732 DOI: 10.1063/1.4895832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a scheme for time-resolved pump-probe microscopy using intensity modulated laser diodes. The modulation frequencies of the pump and probe beams are varied up to 500 MHz with fixed frequency detuning typically set at 15 kHz. The frequency response of the pump-probe signal is detected using a lock-in amplifier referenced at the beat frequency. This frequency domain method is capable of characterizing the nanosecond to picosecond relaxation dynamics of sample species without the use of a high speed detector or a high frequency lock-in amplifier. Furthermore, as the pump-probe signal is based on the nonlinear interaction between the two laser beams and the sample, our scheme provides better spatial resolution than the conventional diffraction-limited optical microscopes. Time-resolved pump-probe imaging of fluorescence beads and aggregates of quantum dots demonstrates that this method is useful for the microscopic analysis of optoelectronic devices. The system is implemented using compact and low-cost laser diodes, and thus has a broad range of applications in the fields of photochemistry, optical physics, and biological imaging.
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Affiliation(s)
- J Miyazaki
- Advanced Ultrafast Laser Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - K Kawasumi
- Advanced Ultrafast Laser Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - T Kobayashi
- Advanced Ultrafast Laser Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
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Miyazaki J, Tsurui H, Hayashi-Takagi A, Kasai H, Kobayashi T. Sub-diffraction resolution pump-probe microscopy with shot-noise limited sensitivity using laser diodes. OPTICS EXPRESS 2014; 22:9024-9032. [PMID: 24787791 DOI: 10.1364/oe.22.009024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We demonstrate the use of intensity-modulated laser diodes to implement pump-probe microscopy and achieved sub-diffraction resolution imaging with shot-noise limited sensitivity with a scheme of balanced detection. This technique has several applications for various types of induced transmission change, including excited-state absorption, ground state absorption bleaching and stimulated emission. By using our technique, biological imaging of mouse T cells and the axons of neurons in the cerebral cortex was demonstrated.
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Abstract
For the past two decades, nonlinear microscopy has been developed to overcome the scattering problem in thick tissue imaging. Owing to its increased imaging depth and high spatial resolution, nonlinear microscopy becomes the first choice for imaging living tissues. The use of nonlinear optical effects not only facilitates the signal originating from an extremely small volume defined by light focusing but also provides novel contrast mechanisms with molecular specificity. Nonlinear absorption is a nonlinear optical effect in which the absorption coefficient depends on excitation intensity. As a commonly used spectroscopy tool, nonlinear absorption measurement uncovers many photophysical and photochemical processes correlated with electronic states of molecules. Recently we have been focusing on adapting this spectroscopy method to a microscopy imaging technique. The effort leads to a novel modality in nonlinear microscopy-nonlinear absorption microscopy. This article summarizes the principles and instrumentation of this imaging technique and highlights some of the recent progress in applying it to imaging skin pigmentation and microvasculature under ex vivo or in vivo conditions.
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Affiliation(s)
- Tong Ye
- Department of Neurobiology, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, USA.
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Fu D, Ye T, Matthews TE, Grichnik J, Hong L, Simon JD, Warren WS. Probing skin pigmentation changes with transient absorption imaging of eumelanin and pheomelanin. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054036. [PMID: 19021416 DOI: 10.1117/1.2976424] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
As some of the most ubiquitous and biologically important natural pigments, melanins play essential roles in the photoprotection of skin. Changes in melanin production could potentially be useful for clinical diagnosis of the progression stage of melanoma. Previously we demonstrated a new method for imaging melanin distribution in tissue with two-color transient absorption microscopy. Here we extend this study to longer wavelengths and show that we are able to image melanin in fixed thin skin slices with higher signal-to-noise ratios (SNRs) and demonstrate epimode imaging. We show that both photothermal effects and long-lived excited states can contribute to the long-lived signal. Eumelanin and pheomelanin exhibit markedly different long-lived excited state absorption. This difference should enable us to map out their respective distribution in tissue samples with subcellular resolution. This technique could provide valuable information in diagnosing the malignant transformation of melanocytes.
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Affiliation(s)
- Dan Fu
- Princeton University, Department of Chemistry, Princeton, New Jersey 08544, USA
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Fu D, Ye T, Matthews TE, Yurtsever G, Warren WS. Two-color, two-photon, and excited-state absorption microscopy. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:054004. [PMID: 17994892 DOI: 10.1117/1.2780173] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We develop a new approach in imaging nonfluorescent species with two-color two-photon and excited state absorption microscopy. If one of two synchronized mode-locked pulse trains at different colors is intensity modulated, the modulation transfers to the other pulse train when nonlinear absorption takes places in the medium. We can easily measure 10(-6) absorption changes caused by either two-photon absorption or excited-state absorption with a RF lock-in amplifier. Sepia melanin is studied in detail as a model system. Spectroscopy studies on the instantaneous two-photon absorption (TPA) and the relatively long-lived excited-state absorption (ESA) of melanin are carried out in solution, and imaging capability is demonstrated in B16 cells. It is found that sepia melanin exhibits two distinct excited states with different lifetimes (one at 3 ps, one lasting hundreds of nanoseconds) when pumped at 775 nm. Its characteristic TPA/ESA enables us to image its distribution in cell samples with high resolution comparable to two-photon fluorescence microscopy (TPFM). This new technique could potentially provide valuable information in diagnosing melanoma.
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Affiliation(s)
- Dan Fu
- Princeton University, Department of Chemistry, Princeton, New Jersey 08544, USA
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Elson DS, Galletly N, Talbot C, Requejo-Isidro J, McGinty J, Dunsby C, Lanigan PMP, Munro I, Benninger RKP, de Beule P, Auksorius E, Hegyi L, Sandison A, Wallace A, Soutter P, Neil MAA, Lever J, Stamp GW, French PMW. Multidimensional Fluorescence Imaging Applied to Biological Tissue. REVIEWS IN FLUORESCENCE 2006 2006. [DOI: 10.1007/0-387-33016-x_22] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Fwu PT, Wang PH, Tung CK, Dong CY. Effects of index-mismatch-induced spherical aberration in pump--probe microscopic image formation. APPLIED OPTICS 2005; 44:4220-7. [PMID: 16045208 DOI: 10.1364/ao.44.004220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Pump--probe fluorescence microscopy has been demonstrated to be a powerful tool for obtaining three-dimensional, time-resolved information in bioimaging applications. However, the use of this technique can be complicated by the fact that the different wavelengths used to achieve pump--probe microscopy can result in wavelength-dependent spherical aberration, thus limiting the usefulness of the technique. We address this issue by investigating the effects of refractive-index-mismatch-induced spherical aberration on pump--probe image formation. We model the effects by considering pump--probe imaging performed with an objective with a numerical aperture of 0.75 focusing through an oil-water interface. Our results show that spherical aberration has the greatest effect in degrading an axial point-spread function. In addition to signal loss, the redistribution of signal strength along the axial direction results in broadening of the FWHM of the plane response function. The inclusion of confocal detection tends to improve image resolution but at a significant loss of signal strength.
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Affiliation(s)
- Peter T Fwu
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
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Watanabe T, Iketaki Y, Omatsu T, Yamamoto K, Fujii M. Two-point separation in far-field super-resolution fluorescence microscopy based on two-color fluorescence dip spectroscopy, Part I: Experimental evaluation. APPLIED SPECTROSCOPY 2005; 59:868-72. [PMID: 16053556 DOI: 10.1366/0003702054411562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The two-point resolution of a novel two-color far-field super-resolution fluorescence microscopy was evaluated by measuring fluorescent beads 100 nm in diameter. This microscopy is based on a combination of two-color fluorescence dip spectroscopy and a phase-modulation technique for a laser beam. By simply introducing two-color laser light, the size of the fluorescent image of a bead was shrunk down to a diameter of 250 nm from the diffraction-limited image with a diameter of 360 nm. For two closely adjacent fluorescent beads with a separation distance of 350 nm, the two-color microscope clearly gave separated fluorescence images, while the conventional one-color fluorescence microscope could not resolve them. It has been proved that our technique breaks Rayleigh's diffraction limit.
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Affiliation(s)
- Takeshi Watanabe
- Tokyo Institute of Technology, Chemical Resources Laboratory, 4259 Nagatsuta-cho, Midoriku, Yokohama 226-8503 Japan
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Dong CY, French T, So PT, Buehler C, Berland KM, Gratton E. Fluorescence-lifetime imaging techniques for microscopy. Methods Cell Biol 2004; 72:431-64. [PMID: 14719344 DOI: 10.1016/s0091-679x(03)72021-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Affiliation(s)
- Chen Y Dong
- Laboratory for Fluorescence Dynamics, Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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