Spatial-offset pump-probe imaging of nonradiative dynamics at optical resolution
Data files
Jun 30, 2025 version files 101.56 MB
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DAS_square_fish_weight.m
1.93 KB
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Figure1.zip
657.22 KB
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Figure2.zip
10.64 MB
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Figure3.zip
82.32 MB
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Figure4.zip
1.46 MB
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Figure5.zip
4.94 MB
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README.md
12.04 KB
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SI.zip
1.53 MB
Abstract
Nonradiative photothermal (PT) and photoacoustic (PA) processes have found widespread applications in imaging, stimulation, and therapy. Mapping the generation and propagation of PA and PT waves with resolution is important to elucidate how these fields interact with biological systems. To this end, we introduce spatial offset pump-probe imaging (SOPPI). By spatially offsetting the pump beam and the probe beam, SOPPI can image simultaneously PA and PT wave propagation with nanosecond temporal resolution, micrometer spatial resolution, 65 MHz detection bandwidth, and a sensitivity of 9.9 Pa noise equivalent pressure. We first map the PA and PT evolution from a fiber emitter, and how the wave interacts with a mouse skull and brain slices. SOPPI imaging of PA waves from a tapered fiber with water as an absorber shows a wavelength-dependent generation, an evanescent wave-generated PA, and a back-propagated acoustic Mach Cone. At last, a SOPPI-PACT is developed to reconstruct the pigment distribution inside a zebrafish larva with high precision and signal-to-noise ratio.
Dataset DOI: 10.5061/dryad.k3j9kd5kt
Description of the data and file structure
The data presented here is for the manuscript titled “Spatial offset pump-probe imaging of nonradiative dynamics at optical resolution”.
Data for each figure are organized separately, from Figure1 to Figure5 and SI.
Figure 1. Using a pump probe method to measure the photoacoustic and photothermal field generated by a fiber.
- (B). Representative AC signal detected by the pump probe imaging system.
*Variable definitions:
PA: Photoacoustic.
PT: Photothermal.
Time: Recording time. Unit: Microsecond.
AC Intensity: The signal recorded in the AC channel to plot the PA and PT traces.
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(C). Decomposition of the raw signal.
*Variable definitions:
Time: Recording time. Unit: Microsecond.
PA: Photoacoustic signal decomposed.
PT: Photothermal signal decomposed.
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(D). Spatial resolution characterization of SOPPI using a 3 μm PMMA bead.
*Variable definitions:
PSF: Point Spread Function.
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(E). PA signal generated by FE and measured by hydrophone (orange) and SOPPI (yellow).
*Variable definitions:
File: Hydrophone_PA_time trace / Hydrophone_PA_frequency spectrum.
Frequency: Ultrasound frequency. Unit: Hz.
Magnitude: Magnitude of the frequency components at different frequencies. (arbitrary unit)
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal detected by the hydrophone. (arbitrary unit)
File: SOPPI_PA_time trace / SOPPI_PA_frequency spectrum.
Frequency: Ultrasound frequency. Unit: Hz.
Magnitude: Magnitude of the frequency components at different frequencies: arbitrary unit
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal detected by the SOPPI: arbitrary unit
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(F). Peak to peak pressure measured by hydrophone and SOPPI plotted as a function of pump energy.
*Variable definitions:
Pump energy: The pulse energy of the pump laser. Unit: microjoule.
SOPPI: Signal amplitude detected by the SOPPI.
Hydrophone: Signal amplitude detected by the hydrophone.
Figure 2. SOPPI reveals the spatial evolution of PA and PT signal generated by a fiber emitter.
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(A). An overlaid image of PA (green) and PT (red) signals at every 100 ns from 0 ns to 1400 ns.
*Variable definitions:
t0 ~ t1400: Image at time = 0 ns ~ 1400 ns.
Overlap: The overlap imaging from t0 to t1400.
- (B). High-frequency component of the PA signal from panel A. Bottom: PA signal amplitude plotted as a function of location.
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(C) Time trace and Fast Fourier transfer of the high-frequency component of the photoacoustic signal.
*Variable definitions:
File: High_frequency_PA frequency spectrum
Frequency: Ultrasound frequency. Unit: Hz.
Magnitude: Magnitude of the frequency components at different frequencies. (arbitrary unit)
File: High_frequency_PA time trace
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal detected by the SOPPI: arbitrary unit
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(D) Spatial distribution of high-frequency PA (orange) and low-frequency PA (blue).
*Variable definitions:
File: High frequency profile
x position: distance away from the fiber emitter. Unit: Micrometer.
Intensity: Field intensity: arbitrary unit
File: Low frequency profile
x position: distance away from the fiber emitter. Unit: Micrometer.
Intensity: Field intensity: arbitrary unit
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(E) Low-frequency component of the PA signal from panel A. Bottom: PA signal amplitude plotted as a function of location
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(F) Time trace and Fast Fourier transfer of the low-frequency component of the photoacoustic signal.
*Variable definitions:
File: Low_frequency_PA frequency spectrum
Frequency: Ultrasound frequency. Unit: Hz.
Magnitude: Magnitude of the frequency components at different frequencies: arbitrary unit
File: Low_frequency_PA time trace
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal detected by the SOPPI: arbitrary unit
- (G) Spatial distribution of the normalized photothermal signal generated by a fiber emitter.
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(H) Representative time trace of the photothermal signal inside and outside the FE.
*Variable definitions:
Time: Recording time. Unit: Microsecond.
Inside: Photothermal trace inside the fiber.
Outside: Photothermal trace outside the fiber.
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(I) PT intensity plotted as a function of distance away from the FE.
*Variable definitions:
Distance: Relative distance from inside to the outside of the fiber. Unit: Micrometer.
Intensity: Relative temperature increase. (arbitrary unit)
Figure 3. SOPPI of PA/PT fields generated by water through a tapered optical fiber.
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(C) PA signals generated from water at different wavelength of pump laser at a location 160 μm away from the tip.
*Variable definitions:
Time: Recording time. Unit: Nanosecond.
PA_1448: PA signal when pump wavelength is 1448 nm. Unit: a.u.
PA_1928: PA signal when pump wavelength is 1928 nm. Unit: a.u.
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(D-E) PA amplitude and frequency spectrum under different wavelength of pump laser in NIR.
*Variable definitions:
File: water_PA and absorption
wavelength: Pump laser wavelength. Unit: nanometer.
absorption: water absorption spectrum: arbitrary unit
PA: water generated PA intensity: arbitrary unit
File: water_PA spectrum
wavelength: Pump laser wavelength. Unit: nanometer.
Frequency: Ultrasound frequency. Unit: MHz.
- (F-J) Spatial distribution of PA (green and yellow) and PT fields (red) at 0-200 ns after the laser was turned on. Dashed boxes: evanescent wave absorption (blue), Mach cone (orange), and tip of the tapered fiber (green)
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(K) three PA waves from evanescent wave absorption (blue), Mach cone (orange), and tip of the tapered fiber (green) at 1920 nm pump. The signal was measured at the “probe” point labeled as purple.
*Variable definitions:
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal generated. arbitrary unit
Figure 4. SOPPI of ultrasound penetrating through mouse brain tissue and skull.
- (A) transmission DC image of the fiber emitter and a brain slice with 500 μm thickness. Scale bar: 100 μm.
- (B) Spatial distribution of FE-generated PA field in brain slice.
- (C) Spatial distribution of PA signal after normalization with respect to DC signals.
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(D) Representative time trace of the incident / transmitted PA signal.
*Variable definitions:
Time: Recording time. Unit: Nanosecond.
Incident US: Amplitude of the incident PA signal generated: arbitrary unit
Transmitted US: Amplitude of the transmitted PA signal generated: arbitrary unit
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(E) PA signal intensity before/after penetrating the brain slice.
*Variable definitions:
Location: Relative location from inside to the outside of the brain slice. Unit: Micrometer.
After correction: PA intensity after correction: arbitrary unit
Before correction: PA intensity before correction: arbitrary unit
- (F) transmission DC image of the fiber emitter and a piece of mouse skull.
- (G) Spatial distribution of the PA field across the skull.
- (H) Nine representative frames of photoacoustic wave penetrating the skull. US: ultrasound.
Figure 5. Photoacoustic computed tomography of a zebrafish using SOPPI.
- (A) Schematic of a PACT imaging of a zebrafish using SOPPI. The probe beam was scanned around the zebrafish following the yellow dashed line.
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(B) Representative PA signal generated by pigments inside the zebrafish and detected by SOPPI.
*Variable definitions:
File: Zebrafish_PA_frequecy spectrum
Frequency: Ultrasound frequency. Unit: Hz.
Magnitude: Magnitude of the frequency components at different frequencies: arbitrary unit
File: Zebrafish_PA_time trace
Time: Recording time. Unit: Nanosecond.
Amplitude: Amplitude of the PA signal generated by pigments in the zebrafish larva: arbitrary unit
- (C) Transmission imaging of a zebrafish.
- (D) Reconstructed mapping of pigments inside the zebrafish using SOPPI-PACT.
- (E) Overlap of transmission and PACT results.
- (F) Comparison of SOPPI-PACT and classic PACT results.
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(G) Comparison of XSSIM and XPSNR between SOPPI-PACT and classic PACT.
*Variable definitions:
SOPPI: XPSNR or XSSIM of SOPPI-PACT result.
classic: XPSNR or XSSIM of classic-PACT result.
Supplementary Information
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Figure S1. Sensitivity characterization of SOPPI. a. SOPPI shows a noise equivalent pressure of 9.89 Pa. b. PA signal from 1.25 mg/ml Hemoglobin in water.
*Variable definitions:
File: Figure S1a
Time: Recording time. Unit: Nanosecond.
PA: Amplitude of the PA signal generated by a fiber emitter: arbitrary unit
File: Figure S1b
Time: Recording time. Unit: Nanosecond.
PA: Amplitude of the PA signal generated by 1.25 mg/ml Hemoglobin in water: arbitrary unit
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Figure S2. SOPPI visualizing near-field acousto-thermal process. a. Four representative frames of PA and PT field distribution. b. signal detected at the boundary of the fiber emitter. c. signal detected inside the fiber emitter.
*Variable definitions:
File: Figure S2b
Time: Recording time. Unit: Nanosecond.
PA: Amplitude of the PA signal generated at position 1: arbitrary unit
File: Figure S2c
Time: Recording time. Unit: Nanosecond.
PA: Amplitude of the PA signal generated at position 2: arbitrary unit
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Figure S5. Background and noise level of SOPPI PACT.
*Variable definitions:
Distance: Relative location in the PACT reconstruction image. Unit: Micrometer.
Intensity: Field intensity: arbitrary unit
DAQ_Square_Fish_Weight
- This is the MATLAB script used to reconstruct the pigment distribution inside the zebrafish using a weighted delay-and-sum algorithm. Details of the algorithm can be found in the Supplementary Information: Weighted-Delay-and-Sum (W-DAS) SOPPI-PACT reconstruction algorithm.