Abstract
We found errors in Eqs. (5), (6), (7), (8), (23), (25), Figs. 2, 3, 4, 5, 10, and Discussion of our article “Three-dimensional wide-field pump-probe structured illumination microscopy.” Here we publish the revised equations, figures, and discussion. In general, the corrections do not affect the essential conclusion and image reconstruction quality improves with these corrections.
© 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
1. Configuration of a wide-field pump-probe structured illumination microscope (ppSIM)
The 3rd plane wave component, of Eq. (5) in [1] has an error for the positive/negative signs in front of the unit vectors in y and z directions. The revised equation is as the following.
The above-mentioned revision affects the plus/minus signs in the following equations and the revised equations for Eq. (6), (7), and (8) in [1] are shown below. The structured pump beam intensity for S-pol interference pattern (Eq. 6) in [1]) can be calculated as
where .By Fourier transforming this pump beam intensity, , we obtain the pump beam spectrum in the spatial-frequency domain (Eq. 7) in [1]) as
where and .Substituting the previous result into Eq. (4) in [1], and mathematically expanding, we get the corresponding image field in the Fourier space (Eq. 8) in [1]) as
2 Appendix A
The light field in the image plane with a shifted object (Eq. (23) in [1]) was represented incorrectly according to the standard convolution definition. The right representation is as the following.
with a change of a integration variable in z direction and a new function . Thus the acquired image field is the 3D convolution of the object function with the point spread function. Here the negative sign before the coordinate variable () inside the point spread function implies that the image is inverted.With the above mentioned change, the final equation for 3D CTF (Eq. (25) in [1]) changes as
where (NA: numerical aperture of the optical system) and is a delta function.This 3D CTF is an axially shifted cap of a paraboloid of revolution about the s axis in Fig. 1(a) (Fig. 10) in [1]). However, this axial shift of the 3D CTF comes from the wave vector of the incident light and the 3D CTF in Fig. 1(a) is a 3D Fourier transform of the diffracted light over the object. Therefore, the effective 3D CTF to measure the pass/block of the object information passes the origin without the axial shift in Fig. 1(b) [2].
3. Theoretical framework
The Fig. 2 corresponds to the Fig. 2 in [1]. In Fig. 2(d)–2(f), we can see the change of 3D CTF. With the revised equations and the effective 3D CTF (without the axial shift), we re-simulated all the results of [1] in the following.
4. Pump-probe structured illumination imaging of a planar target: calibration chart
The Fig. 3 corresponds to the Fig. 3 in [1]. In Fig. 3(a4), 3(b4), and 3(c4), we can see the change of 3D CTF. In both the lateral and axial cases, excellent agreement with the theoretical expectations is observed in Fig. 3(e) and 3(g). The field amplitude modulation of lateral case is close to one because of the dense spatial frequency support in the lateral direction, while that of axial case is smaller than one because of relatively coarse spatial frequency support in the axial direction.
5. Pump-probe structured illumination imaging of a non-planar target: a 3D MIT logo
The re-simulated Fig. 4 in [1] shows almost the same as before except for the better contrast in Fig. 4(c) because near DC spatial information is allowed to pass through the system’s transfer function.
6. Pump-probe structured illumination imaging of biomolecules in HeLa cells
The Fig. 5 corresponds to the Fig. 5 in [1]. In Fig. 5(f3), 3(g3), and 3(h3), we can see the change of 3D CTF. For high NA pump-probe SIM simulation, we changed the NA from 0.9 to 1.0 to match the sectioning capability similar to the previous result (grating period is also changed from 0.84 µm ~2.77 μm to 1.11 µm ~3.66 µm). For all the HEC1 protein and the DNA, both the low NA pump-probe SIM and the high NA pump-probe SIM successfully reconstruct original sample information in both lateral and axial dimensions in Fig. 5(c), 5(d), 5(g), and 5(h). Comparing the images in Fig. 5, we can observe the 3D imaging capability of our grating period scanning pump-probe SIM is consistent regardless of the characteristics of the sample itself and NA of the objective lens.
7. Discussion
We found an error in counting the number of images for the intensity SIM framework to reconstruct a single 3D resolved image (). The revised numbers are images for and images for ). On the other hand, the field SIM framework that we suggested requires 5 pump beams (17 Fourier copies), 4 measurements for optical phase and amplitude, and grating period scanning which results in total images (680 images for and 1088 images for ). In conclusion, our optical field based pump-probe SIM framework requires 30~50 times less number of pump beams and 17~29 times less number of images to reconstruct a single 3D image with the same synthetic CTF than the intensity SIM framework.
Funding
National Institutes of Health (9P41EB015871-26A1, 5R01NS051320, 4R44EB012415, and 1R01HL121386-01A1); National Science Foundation (CBET-0939511); Hamamatsu Corporation; Singapore–Massachusetts Institute of Technology Alliance for Research and Technology (SMART) Center, BioSystems and Micromechanics (BioSyM); Samsung Scholarship.
References and links
1. Y.-H. Kim and P. T. C. So, “Three-dimensional wide-field pump-probe structured illumination microscopy,” Opt. Express 25(7), 7369–7391 (2017). [PubMed]
2. S. S. Kou and C. J. R. Sheppard, “Imaging in digital holographic microscopy,” Opt. Express 15(21), 13640–13648 (2007). [PubMed]