Chao's Blog

(45) 2022-03-15:

(44) 2022-02-04:

(43) 2022-02-03:

(42) 2021-11-19:

• Fiber-tip polymer clamped-beam probe for high-sensitivity nanoforce measurements

(41) 2021-09-19:

• Millimeter-scale chip-based supercontinuum generation for optical coherence tomography

See the sensitivity roll off in the supplementary material

(40) 2021-09-13:

Basic principle of FDOCT, need to understand

• In vivo human retinal imaging by Fourier domain optical coherence tomography

How to measure the dynamic range of Differential FFT OCT system

• Astigmatism Corrected Common Path Probe for Optical Coherence Tomography

(39) 2021-09-09:

• Super-achromatic optical coherence tomography capsule for ultrahigh-resolution imaging of esophagus

• Exposure-dependent refractive index of Nanoscribe IP-Dip photoresist layers

• Ultrafast multi-focus 3-D nano-fabrication based on two-photon polymerization

• Ultrathin fiber probes with extended depth of focus for optical coherence tomography

Use phase mask to increase the depth of focus

(38) 2021-09-08:

• Stitching-free 3D printing of millimeter-sized highly transparent spherical and aspherical optical components

What is stitching? How it works? What is its effect?

(37) 2021-09-07:

• High-sensitivity anastigmatic imaging needle for optical coherence tomography

Cylindrical tube doesn’t necessary make the working distance shorter along azimuthal direction.

• Optical properties of photoresists for femtosecond 3D printing: refractive index, extinction, luminescence-dose dependence, aging, heat treatment and comparison between 1-photon and 2-photon exposure
• Real-time numerical dispersion compensation using graphics processing unit for Fourier-domain optical coherence tomography

(36) 2021-09-06:

• 3D printed hybrid refractive/diffractive achromat and apochromat for the visible wavelength range (Not so optimal)

(35) 2021-08-31:

• Two-photon polymerisation 3D printed freeform micro-optics for optical coherence tomography fibre probes (Some confusion)
• Resolution dependence on phase extraction by the Hilbert transform in phase calibrated and dispersion compensated ultrahigh resolution spectrometer-based OCT (method needs to be verified)

(34) 2021-08-25:

• Microstructured gradient-index antireflective coating fabricated on a fiber tip with direct laser writing
• Direct laser writing of volumetric gradient index lenses and waveguides (Not finished)

(33) 2021-08-24:

• Inverse Design and 3D Printing of a Metalens on an Optical Fiber Tip for Direct Laser Lithography

(32) 2021-08-21:

• Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres (Not finished)

During 3D printing, why high resolution photoresist (IP-Dip) is used for the lower part (close to the fibre end), while low resolution photoresist (IP-S) for the upper part (far from the fibre end)?

• Photonic-dispersion neural networks for inverse scattering problems

(31) 2021-08-20:

• Two-photon direct laser writing of ultracompact multi-lens objectives

(30) 2021-08-19:

• Dual-modality optical coherence tomography and fluorescence tethered capsule endomicroscopy (Not finished)

(29) 2021-08-18:

• Nano-optic endoscope for high-resolution optical coherence tomography in vivo
• Ultrathin monolithic 3D printed optical coherence tomography endoscopy for preclinical and clinical use

Two-photon direct laser writing of ultracompact multi-lens objectives

Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

Aberration characterization for the optimal design of high-resolution endoscopic optical coherence tomography catheters

(28) 2021-08-13: High-resolution OCT balloon imaging catheter with astigmatism correction

(27) 2021-08-12: Depth-resolved model-based reconstruction of attenuation coefficients in optical coherence tomography (to be read again, not fully understand)

Optical phantoms of varying geometry based on thin building blocks with controlled optical properties

(26)2021-08-06:

Optimization for Axial Resolution, Depth Range, and Sensitivity of Spectral Domain Optical Coherence Tomography at 1.3 microns

In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve

(25) 2021-08-05:

(24) 2021-08-04:

• Spectral calibration in spectral domain optical coherence tomography (not finished yet)

(23) 2021-08-03:

• Estimation and compensation of dispersion for a high-resolution optical coherence tomography system (to be simulated)

Dispersion:

High-speed phase- and group-delay scanning with a grating-based phase control delay line

Dual-fiber stretcher as a tunable dispersion compensator for an all-fiber optical coherence tomography system

Dispersion compensation in high-speed optical coherence tomography by acousto-optic modulation

Dispersion compensation in Fourier domain optical coherence tomography

Dispersion compensation for FD-OCT using spectrum reconstruction

Dispersion compensation in Fourier domain optical coherence tomography using the fractional Fourier transform

Demonstration of tolerance to dispersion of master/slave interferometry

Extracting and compensating dispersion mismatch in ultrahigh-resolution Fourier domain OCT imaging of the retina

Ultrahigh-resolution high-speed retinal imaging using spectral-domain optical coherence tomography

Spectral calibration in spectral domain optical coherence tomography

(22) 2021-07-28:

• Diffractive catheter for ultrahigh-resolution spectral-domain volumetric OCT imaging

• Broadband rotary joint for high-speed ultrahigh-resolution endoscopic OCT imaging at 800 nm

• Compensating spatially dependent dispersion in visible light OCT

Fourier domain optical coherence tomography with a linear-in-wavenumber spectrometer

Machine learning optics:

Deep learning in holography and coherent imaging

Extended depth-of-field in holographic imaging using deep-learning-based autofocusing and phase recovery

High-resolution two-photon transcranial imaging of brain using direct wavefront sensing

Endoscopic OCT:

Diffractive catheter for ultrahigh-resolution spectral-domain volumetric OCT imaging (read before)

Broadband rotary joint for high-speed ultrahigh-resolution endoscopic OCT imaging at 800 nm (read before)

OCT sensitivity:

Sensitivity advantage of swept source and Fourier domain optical coherence tomography

Analytical model of spectrometer-based two-beam spectral interferometry

Noise of supercontinuum sources in spectral domain optical coherence tomography

Optimal operational conditions for supercontinuum-based ultrahigh-resolution endoscopic OCT imaging (read before)

Optical attenuation:

Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

Depth-resolved model-based reconstruction of attenuation coefficients in optical coherence tomography

Characterizing optical properties of nano contrast agents by using cross-referencing OCT imaging

(19) 2021-07-26: Machine learning and applications in ultrafast photonics

Not finished yet.

The polarization state of the sample and reference arm was carefully managed by using polarization controllers to maximize the interference fringe contrast.

The fluctuation in the double-pass coupling efficiency was measured by connecting a short piece (∼5 cm long) of flat cleaved fiber to the rotary arm. The fluctuation of backreflected light intensity from the fiber tip during circumferential scanning was measured to be less than ±2% at a speed of 5 revolution/s (rps).

The shot-noise density per detector element is reduced by a factor of 2 because only half of the reference arm’s optical power is incident upon each detection element.

Extending the above analysis demonstrates that the shot-noise contribution to the system is reduced by a factor approximately equal to the number of detectors over which the spectrum is dispersed.

By use of Nyquist’s theorem, the bandwidth per detector element (BW/M) in Eq. (8) is replaced by 1/(2${\tau _i}$), where ${\tau _i}$ is the integration time of the array.

In conclusion, the increased SNR in SD OCT compared with that of TD OCT is based on the significant reduction of shot noise obtained by replacement of the single-element detector with a multielement array detector.

(13) 2021-07-03: Optimal interferometer designs for optical coherence tomography

It is clear that maximizing the SNR for the standard OCT interferometer requires low reference-arm reflectivity .

The objective-first inverse method is used to design a metalens, which can be fabricated on the tip of a single mode fibre. The circular metalens can transform the parallel waveform to spherical wavefront, with a focal length of 8 um at the wavelength of 980 nm and a focal spot of 100 nm. For its demonstration use, the metalens is integrated with a 780 nm laser platform for two-photon direct laser lithography.

Insight: Can I use this design method to create desired pattern for ball lens used in the catheter?

Limitation: Manual control in the z-axis for the laser lithography.

(10) 2021-03-16: Analysis of intermediary scan-lens and tube-lens mechanisms for optical coherence tomography (in reading)

A 25-gauge hypodermic tube with a side opening was employed to protect the distal end, and a torque coil of a 600 µm diameter was used to protect the rest of the optical fiber and transfer rotation from the proximal to the distal end for performing circumferential beam scanning.

(4) 2021-02-25: Mems scanning mirrors for optical coherence tomography (in reading)

A system that can acquire essentially crosstalk-free volumes of the retina by using a fast deformable membrane.

(1) 2021-02-20: Microrobotic laser steering for minimally invasive surgery