Abstract:We demonstrate a multi-color background-free coherent anti-Stokes Raman scattering (CARS) imaging system, using a robust, all-fiber, low-cost, multi-wavelength timelens source. The time-lens source generates picosecond pulse trains at three different wavelengths. The first is 1064.3 nm, the second is tunable between 1052 nm and 1055 nm, and the third is tunable between 1040 nm and 1050 nm. When the time-lens source is synchronized with a mode-locked Ti:Sa laser, two of the three wavelengths are used to detect … Show more
“…The existence of the nonresonant background can either distort or even saturate the resonant signal of Raman peaks, which reduces the image contrast. Qin et al [278] have recently demonstrated multi-colour background-free coherent anti-Stokes Raman scattering microscopy using an all-fibre, low-cost, multi-wavelength time lens source. A time lens, in analogy to a spatial lens, is simply a quadratic optical phase modulator in time, which can be approximated by a portion of a sinusoidal phase modulator [279–281].…”
Section: Recent Resultsmentioning
confidence: 99%
“…Pixel-to-pixel wavelength switching was achieved, which provided simultaneous two-colour CARS imaging with real-time nonresonant background subtraction. Qin et al [278] demonstrated the technique with an excised fresh tissue sample from a mouse ear and imaged molecular stretching vibrations at 2845 cm −1 (CH 2 ) and 2940 cm −1 (CH 3 ) and non-resonance background at = 2770 cm −1 . Figure 7a i–iii shows the process applied to the Raman peak of CH 3 stretching vibration from the mouse ear tissue sample.Fig.…”
Section: Recent Resultsmentioning
confidence: 99%
“…c High-speed polarisation-resolved CARS image sequence on a MLV moving over the sample surface taken at different times of the observation sequence shown as a composite image of S 2 and φ 2 as coloured sticks and with the acousto-optic modulation (AOM) as a grey background. a reproduced with permission from the OSA [278]. b Adapted from [289] and licenced under CC BY 4.0. c reproduced with permission from the OSA [259].…”
Driven by applications in chemical sensing, biological imaging and material characterisation, Raman spectroscopies are attracting growing interest from a variety of scientific disciplines. The Raman effect originates from the inelastic scattering of light, and it can directly probe vibration/rotational-vibration states in molecules and materials. Despite numerous advantages over infrared spectroscopy, spontaneous Raman scattering is very weak, and consequently, a variety of enhanced Raman spectroscopic techniques have emerged. These techniques include stimulated Raman scattering and coherent anti-Stokes Raman scattering, as well as surface- and tip-enhanced Raman scattering spectroscopies. The present review provides the reader with an understanding of the fundamental physics that govern the Raman effect and its advantages, limitations and applications. The review also highlights the key experimental considerations for implementing the main experimental Raman spectroscopic techniques. The relevant data analysis methods and some of the most recent advances related to the Raman effect are finally presented. This review constitutes a practical introduction to the science of Raman spectroscopy; it also highlights recent and promising directions of future research developments.
“…The existence of the nonresonant background can either distort or even saturate the resonant signal of Raman peaks, which reduces the image contrast. Qin et al [278] have recently demonstrated multi-colour background-free coherent anti-Stokes Raman scattering microscopy using an all-fibre, low-cost, multi-wavelength time lens source. A time lens, in analogy to a spatial lens, is simply a quadratic optical phase modulator in time, which can be approximated by a portion of a sinusoidal phase modulator [279–281].…”
Section: Recent Resultsmentioning
confidence: 99%
“…Pixel-to-pixel wavelength switching was achieved, which provided simultaneous two-colour CARS imaging with real-time nonresonant background subtraction. Qin et al [278] demonstrated the technique with an excised fresh tissue sample from a mouse ear and imaged molecular stretching vibrations at 2845 cm −1 (CH 2 ) and 2940 cm −1 (CH 3 ) and non-resonance background at = 2770 cm −1 . Figure 7a i–iii shows the process applied to the Raman peak of CH 3 stretching vibration from the mouse ear tissue sample.Fig.…”
Section: Recent Resultsmentioning
confidence: 99%
“…c High-speed polarisation-resolved CARS image sequence on a MLV moving over the sample surface taken at different times of the observation sequence shown as a composite image of S 2 and φ 2 as coloured sticks and with the acousto-optic modulation (AOM) as a grey background. a reproduced with permission from the OSA [278]. b Adapted from [289] and licenced under CC BY 4.0. c reproduced with permission from the OSA [259].…”
Driven by applications in chemical sensing, biological imaging and material characterisation, Raman spectroscopies are attracting growing interest from a variety of scientific disciplines. The Raman effect originates from the inelastic scattering of light, and it can directly probe vibration/rotational-vibration states in molecules and materials. Despite numerous advantages over infrared spectroscopy, spontaneous Raman scattering is very weak, and consequently, a variety of enhanced Raman spectroscopic techniques have emerged. These techniques include stimulated Raman scattering and coherent anti-Stokes Raman scattering, as well as surface- and tip-enhanced Raman scattering spectroscopies. The present review provides the reader with an understanding of the fundamental physics that govern the Raman effect and its advantages, limitations and applications. The review also highlights the key experimental considerations for implementing the main experimental Raman spectroscopic techniques. The relevant data analysis methods and some of the most recent advances related to the Raman effect are finally presented. This review constitutes a practical introduction to the science of Raman spectroscopy; it also highlights recent and promising directions of future research developments.
“…PBS2 (PBS102, Thorlabs) combined ARM1 and ARM2. Spatial synchronizations of two arms were achieved by using similar methods to those described in [18]. We placed a quarter-wave plate (QWP, WPQ05M-850, Thorlabs) and an EOM (EO-AM-NR-C1, Thorlabs) after PBS2.…”
Section: Methodsmentioning
confidence: 99%
“…In addition, using near infrared (NIR) excitation wavelengths also increases the penetration depth, which is particularly significant for biomedical imaging [10][11][12]. Multiphoton microscopy (MPM) and coherent Raman scattering (CRS) microscopy are the most frequently applied nonlinear imaging technologies for biomedical microscopy [13][14][15][16][17][18]. The former mainly includes two-photon fluorescence (TPF), three-photon fluorescence (ThPF), second-harmonic generation (SHG), and third-harmonic generation (THG) microscopy.…”
Multiphoton microscopy is a well-established technique for biomedical applications, but real-time multidepth multimodal multiphoton microscopy using non-imaging detection has barely been discussed. We demonstrate a novel label-free imaging system capable of generating multimodal multiphoton signals at different focal planes simultaneously. Two spatially overlapped and temporally interlaced beams are obtained by applying cost-effective electro-optic modulator (EOM)-based fast-switching light paths. The switching beams have different divergence properties, enabling imaging at different depths into samples. The EOM is synchronized to the pixel clock from the microscope, achieving pixel-to-pixel focus-switching. The capability of the imaging system is demonstrated by performing real-time multidepth two-photon fluorescence (TPF) and second-harmonic generation (SHG) imaging of freshly excised mouse lung lobes. TPF and SHG images are acquired at two wavelength ranges. One is between 415 and 455 nm, and the other is between 495 and 635 nm. The microenvironment of pulmonary alveoli is depicted by the distributions of both elastin fibers visualized by TPF and collagen fibers illustrated by SHG. Macrophages residing inside apparent alveolar lumens are also identified by TPF, which shows that the imaging system is capable of localizing biological objects in three dimensions and has the potential of monitoring in vivo cellular dynamics in the axial direction.
We use the time-lens concept to demonstrate a new scheme for synchronization of two pulsed light sources for biological imaging. An all fiber, 1064 nm time-lens source is synchronized to a picosecond solid-state Ti: Sapphire mode-locked laser by using the mode-locked laser pulses as the clock. We demonstrate the application of this synchronized source for CARS and SRS imaging by imaging mouse tissues. Synchronized two wavelength pulsed source is an important technical difficulty for CARS and SRS imaging. The time-lens source demonstrated here may provide an all fiber, user friendly alternative for future SRS imaging.
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