Browsing by Author "Kawasumi, Koshi"

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Optimal detection angle in sub-diffraction resolution photothermal microscopy: application for high sensitivity imaging of biological tissues
(2014-08-11)
Miyazaki, Jun
;
Tsurui, Hiromichi
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
We evaluated the optimal detection angle for maximizing the signal to noise ratio (SNR) in sub-diffraction resolution photothermal microscopy. The angular dependent photothermal signal was calculated based on scattering theory using the temporally modulated Yukawa potential, and its detection angle and modulation frequency dependencies were analyzed. We verified the theoretical findings by imaging gold nanoparticles using laser diode based photothermal microscopy with balanced detection scheme. High-sensitivity (SNR similar to 40) photothermal biological imaging of a mouse brain was also demonstrated.
Optimal detection angle in sub-diffraction resolution photothermal microscopy: application for high sensitivity imaging of biological tissues
(2014-08-11)
Miyazaki, Jun
;
Tsurui, Hiromichi
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
We evaluated the optimal detection angle for maximizing the signal to noise ratio (SNR) in sub-diffraction resolution photothermal microscopy. The angular dependent photothermal signal was calculated based on scattering theory using the temporally modulated Yukawa potential, and its detection angle and modulation frequency dependencies were analyzed. We verified the theoretical findings by imaging gold nanoparticles using laser diode based photothermal microscopy with balanced detection scheme. High-sensitivity (SNR similar to 40) photothermal biological imaging of a mouse brain was also demonstrated. (C) 2014 Optical Society of America
"Optimal detection angle in sub-diffraction resolution photothermal microscopy: application for high sensitivity imaging of biological tissues": reply
(2015-03-09)
Miyazaki, Jun
;
Tsurui, Hiromichi
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
The differences between our model and existing models are rationalized in terms of the experimental conditions. The theory in [Opt. Express 22(16), 18833-18842 (2014)] is applicable when the temperature increase is moderate (similar to 1 K) and the spatial extend of refractive index being modulated is comparable to or smaller than the wavelength, which are in accordance with our experiment. (C) 2014 Optical Society of America
Resolution enhancement of pump-probe microscope with an inverse-annular filter
(2018-04-01)
Kobayashi, Takayoshi
;
Kawasumi, Koshi
;
Miyazaki, Jun
;
Nakata, Kazuaki
;
電子物理學系
Optical pump-probe microscopy can provide images by detecting changes in probe light intensity induced by stimulated emission, photoinduced absorbance change, or photothermal-induced refractive index change in either transmission or reflection mode. Photothermal microscopy, which is one type of optical pump-probe microscopy, has intrinsically super resolution capability due to the bilinear dependence of signal intensity of pump and probe. We introduce new techniques for further resolution enhancement and fast imaging in photothermal microscope. First, we introduce a new pupil filter, an inverse-annular pupil filter in a pump-probe photothermal microscope, which provides resolution enhancement in three dimensions. The resolutions are proved to be improved in lateral and axial directions by imaging experiment using 20-nm gold nanoparticles. The improvement in X (perpendicular to the common pump and probe polarization direction), Y (parallel to the polarization direction), and Z (axial direction) are by 15 +/- 6, 8 +/- 8, and 21 +/- 2% from the resolution without a pupil filter. The resolution enhancement is even better than the calculation using vector field, which predicts the corresponding enhancement of 11, 8, and 6%. The discussion is made to explain the unexpected results. We also demonstrate the photothermal imaging of thick biological samples (cells from rabbit intestine and kidney) stained with hematoxylin and eosin dye with the inverse-annular filter. Second, a fast, high-sensitivity photothermal microscope is developed by implementing a spatially segmented balanced detection scheme into a laser scanning microscope using a Galvano mirror. We confirm a 4.9 times improvement in signal-to-noise ratio in the spatially segmented balanced detection compared with that of conventional detection. The system demonstrates simultaneous bi-modal photothermal and confocal fluorescence imaging of transgenic mouse brain tissue with a pixel dwell time of 20 mu s. The fluorescence image visualizes neurons expressing yellow fluorescence proteins, while the photothermal signal detected endogenous chromophores in the mouse brain, allowing 3D visualization of the distribution of various features such as blood cells and fine structures most probably due to lipids. This imaging modality was constructed using compact and cost-effective laser diodes, and will thus be widely useful in the life and medical sciences. Third, we have made further resolution improvement of high-sensitivity laser scanning photothermal microscopy by applying non-linear detection. By this, the new method has super resolution with 61 and 42% enhancement from the diffraction limit values of the probe and pump wavelengths, respectively, by a second-order non-linear scheme and a high-frame rate in a laser scanning microscope. The maximum resolution is determined to be 160 nm in the second-order non-linear detection mode and 270 nm in the linear detection mode by the PT signal of GNPs. The pixel rate and frame rate for 300 x 300 pixel image are 50 mu s and 4.5 s, respectively. The pixel and frame rate are shorter than the rates, those are 1 ms and 100 s, using the piezo-driven stage system.
Resolution improvement in laser diode-based pump-probe microscopy with an annular pupil filter
(2014-07-15)
Miyazaki, Jun
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
;
Department of Electrophysics
We experimentally demonstrate the use of annular beams to improve lateral resolution in laser-diode-based pump-probe microscopy. We found that the width of the point-spreading function in the case of the annular pump-probe beams is 162 nm, which is 30% smaller than that of the circular beams (232 nm). Furthermore, side lobes were efficiently suppressed at the focal plane since the pump-probe signal is proportional to the product of the two beam intensities. This scheme is demonstrated for the photothermal signal of nonfluorescent gold nanoparticles and the stimulated emission signal of fluorescence beads. (C) 2014 Optical Society of America
Sensitivity enhancement of photothermal microscopy with radially segmented balanced detection
(2015-02-15)
Miyazaki, Jun
;
Tsurui, Hiromichi
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
A novel detection method is proposed for highly sensitive photothermal microscopic imaging. This method is based on the characteristics of an angular-dependent photothermal signal; it improves signal intensity by up to two times and rejects the intensity noise of the probe beam. The subdiffraction resolution photothermal imaging of mouse skin melanoma is demonstrated using a laser diode-based photothermal microscopy system to evaluate this method. We confirm that the signal intensity is enhanced 1.7 times compared with the conventional detection method. Moreover, the intensity noise of the laser diode used for the probe beam is effectively reduced by approximately 31 dB, even for a sample with non-uniformity of the refractive index and stationary absorption. This method is implemented by means of a commonly used balanced detector and is thus potentially useful for high-speed imaging. (C) 2015 Optical Society of America
Simultaneous dual-wavelength imaging of nonfluorescent tissues with 3D subdiffraction photothermal microscopy
(2015-02-09)
Miyazaki, Jun
;
Tsurui, Hiromichi
;
Kawasumi, Koshi
;
Kobayashi, Takayoshi
;
電子物理學系
Multi-wavelength microscopic imaging is essential to visualize a variety of nanoscale cellular components with high specificity and high spatial resolution. However, previous techniques are based on fluorescence, and thus cannot visualize nonfluorescent species, which are much less suffered from photodamage or photobleaching and hence are intrinsically useful in wider range of optical microscopy. Here, we show that simultaneous multi-wavelength imaging of nonfluorescent species can be achieved with the use of a photothermal microscope. Dual-wavelength subdiffraction imaging of biological tissues stained with hematoxylin and eosin is demonstrated. Three-dimensional label-free imaging of mouse melanoma tissue section is also presented to demonstrate the effectiveness of the enhanced spatial resolution. Our technique can be implemented using cost-effective and compact laser diodes and is applicable for various types of both fluorescent and nonfluorescent tissues. (C) 2015 Optical Society of America