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.

A Simple Doublet Lens Design for Mid-Infrared Imaging

“…This is due, in part, to a reduction in coherent ringing artifacts that have previously been reported in coherent MIR imaging. 59,68,69 Additionally, when normalizing the grating MTF with coherent light to 0 lp/mm, Figure 6, the experimental doublet produced an MTF that follows a similar shape as the simulated doublet MTF produced in OpticStudio shown in Figure 3. Imaging done with incoherent light, however, did not produce the same results.…”

“…This is unexpected given our previous work, in which the microspheres enabled us to resolve gratings at much higher spatial frequencies than calculated frequency cutoffs would predict. 59 One possibility for this could be due to an effect caused by the addition of the CaF 2 lens. We hypothesize that because PS has a MIR refractive index similar to CaF 2 , 53 the ZnSe asphere and PS previously acted to offset each other, similar to a crude doublet lens.…”

A Simple Doublet Lens Design for Mid-Infrared Imaging

“…This is due, in part, to a reduction in coherent ringing artifacts that have previously been reported in coherent MIR imaging. 59,68,69 Additionally, when normalizing the grating MTF with coherent light to 0 lp/mm, Figure 6, the experimental doublet produced an MTF that follows a similar shape as the simulated doublet MTF produced in OpticStudio shown in Figure 3. Imaging done with incoherent light, however, did not produce the same results.…”

“…This is unexpected given our previous work, in which the microspheres enabled us to resolve gratings at much higher spatial frequencies than calculated frequency cutoffs would predict. 59 One possibility for this could be due to an effect caused by the addition of the CaF 2 lens. We hypothesize that because PS has a MIR refractive index similar to CaF 2 , 53 the ZnSe asphere and PS previously acted to offset each other, similar to a crude doublet lens.…”

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.…”

“…In addition, Modulation transfer function (MTF) has been used to evaluate the resolution capability of the microsphere imaging system. 18 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 is reported that the resolution of microsphere-assisted microscopy would be enhanced toward 0.14λ by introducing a short-period plasmonic metasurface substrate used for coupling of the emission of fluorescently labeled nanoscale objects.…”

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]…”

A Simple Doublet Lens Design for Mid-Infrared Imaging

“…This is due, in part, to a reduction in coherent ringing artifacts that have previously been reported in coherent MIR imaging. 59,68,69 Additionally, when normalizing the grating MTF with coherent light to 0 lp/mm, Figure 6, the experimental doublet produced an MTF that follows a similar shape as the simulated doublet MTF produced in OpticStudio shown in Figure 3. Imaging done with incoherent light, however, did not produce the same results.…”

“…This is unexpected given our previous work, in which the microspheres enabled us to resolve gratings at much higher spatial frequencies than calculated frequency cutoffs would predict. 59 One possibility for this could be due to an effect caused by the addition of the CaF 2 lens. We hypothesize that because PS has a MIR refractive index similar to CaF 2 , 53 the ZnSe asphere and PS previously acted to offset each other, similar to a crude doublet lens.…”

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.…”

“…In addition, Modulation transfer function (MTF) has been used to evaluate the resolution capability of the microsphere imaging system. 18 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 is reported that the resolution of microsphere-assisted microscopy would be enhanced toward 0.14λ by introducing a short-period plasmonic metasurface substrate used for coupling of the emission of fluorescently labeled nanoscale objects.…”

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]…”

A Simple Doublet Lens Design for Mid-Infrared Imaging

“…This is due, in part, to a reduction in coherent ringing artifacts that have previously been reported in coherent MIR imaging. 59,68,69 Additionally, when normalizing the grating MTF with coherent light to 0 lp/mm, Figure 6, the experimental doublet produced an MTF that follows a similar shape as the simulated doublet MTF produced in OpticStudio shown in Figure 3. Imaging done with incoherent light, however, did not produce the same results.…”

“…This is unexpected given our previous work, in which the microspheres enabled us to resolve gratings at much higher spatial frequencies than calculated frequency cutoffs would predict. 59 One possibility for this could be due to an effect caused by the addition of the CaF 2 lens. We hypothesize that because PS has a MIR refractive index similar to CaF 2 , 53 the ZnSe asphere and PS previously acted to offset each other, similar to a crude doublet lens.…”

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.…”

“…In addition, Modulation transfer function (MTF) has been used to evaluate the resolution capability of the microsphere imaging system. 18 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 is reported that the resolution of microsphere-assisted microscopy would be enhanced toward 0.14λ by introducing a short-period plasmonic metasurface substrate used for coupling of the emission of fluorescently labeled nanoscale objects.…”

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]…”