Coherent Optical Adaptive Techniques

Bridges, William B.; Brunner, P.; Lazzara, Samuel P.; Nussmeier, T. A.; O'Meara, T. R.; Sanguinet, J. A.; Brown, W. P.

doi:10.1364/ao.13.000291

Cited by 100 publications

(25 citation statements)

References 1 publication

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“…In the first phase of development, upto early 1980's adaptive optic systems were developed mainly for defence purposes in which the primary goal was to achieve an operating capability for a high percentage of time, even under bad conditions. The first practical successes in real-time compensation of atmospheric turbulence was achieved in the 1970's with laser sources and bright stars 2,3,4 . These experiments proved that real-time compensation of optical wavefront distortion was feasible, promising enormous benefits for ground-based astronomy if the practical obstacles could be overcome.…”

Section: Introductionmentioning

confidence: 99%

Measurement of atmospheric turbulence parameters relevant to adaptive optic system design

Razdan¹

2003

Atmospheric Propagation

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Experimental measurements to investigate the effects of atmospheric turbulence on two major parameters for laser adaptive optic (AO) system design (turbulence coherence length r 0 and the atmospheric time constant τ 0) were carried out to cover weak, moderate and strong turbulence conditions prevailing in the city of Delhi (India). Diurnal and seasonal variation of atmospheric refractive index structure parameter (C n 2 ) near the ground was measured with a minimum and maximum recorded values of 2 x10 -13 m -2/3 and 10 -11 m -2/3 respectively. Estimated values of r 0 range from 0.42 mm to 4.4 mm (for 0.6328 µm wavelength of He-Ne laser), 0.8 mm to 8.3 mm (for 1.06 µm wavelength of Nd:YAG laser), 1 mm to 10.5 mm (for 1.3 µm wavelength of Chemical Oxy-Iodine laser), 3.7 mm to 38.2 mm (for 3.8 µm wavelength of DF laser) and 12.5 mm to 131 mm for 10.6 µm CO 2 laser wavelength, each for measured C n 2 values of 10 -11 m -2/3 to 2 x10 -13 m -2/3 . Intensity autocorrelation function measurements of laser scintillations indicate that a bandwidth of ~ 0.5 kHz (corresponding to measured τ 0 ~ 2.25 ms)is required for the adaptive optic system to operate effectively in our conditions. Laser beam wander exceeding 100 µrad (both at 0.6328 µm and 1.06 µm wavelengths) at frequencies ranging from 10-20 Hz were observed under strong turbulence conditions. Estimation of number of correction zones for deformable mirror indicate that for the measured turbulence strengths in our atmosphere, the complexity of the AO system at 1.06 µm, 1.3 µm and 3.8 µm wavelengths will be very high as compared to 10.6 µm system where the actuator requirements are much less and within manageable range.

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Section: Introductionmentioning

confidence: 99%

Measurement of atmospheric turbulence parameters relevant to adaptive optic system design

Razdan¹

2003

Atmospheric Propagation

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“…The COAT method has been demonstrated recently in microscopy imaging [19, 21] to achieve high speed and high precision wavefront control with improved freedom in comparison to the Zernike polynomials based methods. Since the depletion beam has more impact on the resolution, we only did aberration correction with the SLM on the depletion beam.…”

Section: Aberration Correctionmentioning

confidence: 99%

“…Here, we report an aberration correction approach in STED microscopy by measuring the phase distortion of samples with the COAT method. Originally developed for astronomy imaging, the COAT method was introduced to the optical microscopy field recently in optimizing the light focusing in scattering media [19]. In our experiment, a spatial light modulator (SLM) was introduced to the depletion beam path to provide both the spiral phase for generating the doughnut-shaped focus and the correction phase for reducing aberrations.…”

Section: Introductionmentioning

confidence: 99%

Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

et al. 2017

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Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens’ optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples.

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“…They assumed that if the achieved phase pattern could correct the wavefront aberration of a Gaussian beam, it could also compensate that of a doughnut beam . COAT was first developed for beam focusing through air turbulence by Hughes Research Laboratories in the 1970s , and then introduced to microscopy . Instead of the pixel‐by‐pixel correction method, this indirect parallel wavefront optimization method can focus light into strong scattering media with high efficiency.…”

Section: Introductionmentioning

confidence: 99%

Aberration corrections of doughnut beam by adaptive optics in the turbid medium

Chen

et al. 2019

Journal of Biophotonics

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The doughnut beam is a spatially structured beam which has been widely used in super-resolution microscopy, laser trapping and so on. However, when it passes through thick scattering medium, aberrations will seriously affect its performance. Currently, adaptive optics (AO) has become one of the most powerful tools to compensate aberrations. However, conventional AO always suffers from limited corrected field of view (FOV). Here, we propose a method with conjugate AO system based on coherent optical adaptive technique. The results show that the corrected FOV can be improved effectively. For a wide range of the optical applications with doughnut beam, our method has potentials in correcting aberrations with high speed in turbid media.(A) Mouse brain slice, (B) the distribution of r PAO , (C) the distribution of r CAO . The vortex beam focus of the blue point in (B) and (C) among a 137.5 × 137.5 μm FOV (D1) ideally, (D2) with scattering, (D3) in pupil AO system and (D4) in conjugate AO system. K E Y W O R D S aberration correction, adaptive optics, doughnut beam, turbid medium

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Coherent Optical Adaptive Techniques

Cited by 100 publications

References 1 publication

Measurement of atmospheric turbulence parameters relevant to adaptive optic system design

Measurement of atmospheric turbulence parameters relevant to adaptive optic system design

Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

Aberration corrections of doughnut beam by adaptive optics in the turbid medium

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