Resolution Enhancement in Wide-Field IR Imaging and Time-Domain Spectroscopy Using Dielectric Microspheres

Abstract

Wide-field imaging through dielectric microspheres has emerged in recent years as a simple and effective approach for generating super-resolution images at visible wavelengths. We present, to our knowledge, the first demonstration that dielectric microspheres can be used in a wide-field infrared (IR) microscope to enhance the far field resolution. We have observed a substantial improvement in resolution and magnification when images are collected through polystyrene microspheres. In addition, we demonstrate that spectroscopic imaging with a pulse-shaper based femtosecond mid-IR laser system is possible through the dielectric microspheres, which is a promising first step toward applying this technique to ultrafast IR imaging methods such as pump–probe and 2DIR microscopy.

Converting Evanescent Waves into Propagating Waves: The Super-Resolution Mechanism in Microsphere-Assisted Microscopy

“…The resolution of BTG microspheres fully immersed in ethanol can reach 0.19 ± 0.01 λ. In addition, Modulation transfer function (MTF) has been used to evaluate the resolution capability of the microsphere imaging system . The experimental results of using MTF to evaluate the impact of the immersion depth on the resolution of microspheres are shown in Figures S3 and S4.…”

“…It has been proven that microsphere-assisted microscopy is a simple and effective method to observe unlabeled nanoscale objects or viruses. , Microsphere-assisted microscopy generally works by introducing a dielectric microsphere with a diameter of 5–100 μm between the objective lens and the sample, and the information of the object is first magnified by the microsphere and then collected by the objective lens of an optical microscope. − The subwavelength focusing and super-resolution imaging capabilities of microspheres have been widely used in the fields of biology and physical chemistry, such as single-molecule imaging, fluorescence enhancement, spectroscopic imaging, and microsphere-enhanced Raman scattering microscopy . The above results show the potential of microsphere lenses in the field of physical chemistry and exploring the imaging mechanism of microspheres will provide more inspiration for the application of microsphere lenses in this field.…”

Chalcogenide Microsphere‐Assisted Optical Super‐Resolution Imaging

“…Moreover, benefiting from the broadband infrared transparency (up to 6 µm wavelength) of the As 2 S 3 glass, As 2 S 3 microspheres show great potentials as a new vibrational super-resolved imaging approach in the mid-infrared region. [42,43]…”

Leaving the Limits of Linearity for Light Microscopy

“…These implementations can be complex or require high powers, which can induce sample damage, and few applications have been reported. Newer designs are still being sought including, for example, a proposed structured illumination in a wide field geometry that has been proposed but not implemented and the recent report of dielectric microspheres for resolution improvement in the IR . An alternative may be a completely computational approach via deep learning that has been demonstrated for linear fluorescence microscopy …”

“…Newer designs are still being sought including, for example, a proposed structured illumination in a wide field geometry that has been proposed but not implemented 48 and the recent report of dielectric microspheres for resolution improvement in the IR. 49 An alternative may be a completely computational approach via deep learning that has been demonstrated for linear fluorescence microscopy. 50 The strength of TAM to acquire information across spatial, temporal, and spectral dimensions also represents one of its greatest weaknesses for collecting data in reasonable timeframes.…”