Calcination-Enhanced Laser-Induced Damage Threshold of 3D Micro-Optics Made with Laser Multi-Photon Lithography
, Rokas Zvirblis 1, Karolis Galvanauskas 1, Gintare Bataviciute 2 and Mangirdas Malinauskas 1,*
Thomas Gischkat
Round 1
Reviewer 1 Report
This work is a pilot study to report the femtosecond Laser-Induced Damage Threshold (LIDT) results using Series-on-1 protocol for non-calcinated and calcinated suspended micro-lenses. The authors demonstrate that the LIDT increased multiple times when the SZ2080TM micro-structures by Laser Direct Writing subsequently heat treated. These findings could provide important insights for the development of robust micro-optical devices.
My comments and questions:
1. How uniform, in terms of the chemical composition, is the drop-casted prepolymer SZ2080TM coating on a quartz substrate (sample by sample) and how much does the quality (purity, roughness) of the quartz (or fused silica) substrate itself affect the fabrication of microstructures and overall results?
2. How is the length of the femtosecond laser pulses measured and controlled?
3. How much can the heating time affect the results, i.e. 1h vs. 3h?
4. How much can humidity affect the heating process?
5. In line 102: …”damage sites for NCA lenses (Fig. 2 (b))”… Should not there be a Fig. 3(b) instead of Fig. 2 (b)?
6. In line 297, could you please add more information about reference 39 OrmoComp®.
It is well written. It is worthy of acceptance if the sections I commented on to the author can be corrected.
Author Response
- How uniform, in terms of the chemical composition, is the drop-casted prepolymer SZ2080TM coating on a quartz substrate (sample by sample) and how much does the quality (purity, roughness) of the quartz (or fused silica) substrate itself affect the fabrication of microstructures and overall results?
When used fresh, SZ2080 can be considered unifom and chemically pure. Drop casting does not introduce any aditional impurities. In our case when fabricating top to bottom, drop casting has no effect on performance.
- How is the length of the femtosecond laser pulses measured and controlled?
Laser used is a commercial product, specifications are validated by the producer.
- How much can the heating time affect the results, i.e. 1h vs. 3h?
Shorter heating rise time results in trapped unoxydized carbon inside structures. Shorter hold times may result in deformations due to chemical processes being incomplete
- How much can humidity affect the heating process?
Calcination done in 1100C, is not affected by moisture. Oxygen content and it‘s diffusivity, however, could do, since the oxydation of carbon removes the organic part of the polymer.
- In line 102: …”damage sites for NCA lenses (Fig. 2 (b))”… Should not there be a Fig. 3(b) instead of Fig. 2 (b)?
Thank you, correction was made
- In line 297, could you please add more information about reference 39 OrmoComp®.
Link was added, thank you for noticing - https://www.microresist.de/en/produkt/ormocomp/
It is well written. It is worthy of acceptance if the sections I commented on to the author can be corrected.
We thank the Reviewer for the positive evaluation.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear authors
Thank you very much for your work and your investigations on the LIDT of 3D micro-optics by means of LDW. The paper is well written and everything is well described and explained. But there are a few comments and suggestions for improving the manuscript:
Section 2:
Figure 1: As the figure is mentioned/introduced in section 1 and section 2 I would suggest to split it into two pictures (1) a and b for fabrication and 2) c for Testing -> include in fig 2 on page 3). What do you mean with delocalised regime and lens array in the picture?
Page 2, line 67: I would suggess to introduce the NCA and CA here -> is referred to ...
Page 3, line 69: (also in fig 1): Is it necessarry/important to the work to mention the darkening at 600°C?
3. LIDT Metrology
Page 3, line 76: What do you mean with "image function"? Can describe in more detail
Figure 3, figure descritption: not clear, should be revised
4. Results
Page 4, line 100: I do not understand. In Figure 1 a) a NCA lense is shown?
Page 4, line 104 ff.: This section need a little bit more logical structure. It jumps between results for NCA and CA.
Page 4, line 110 ff.: I think one point has to be taken into account is the refractive index (band edge) and the absorption as well as the microstructure of the material. In generall it would be beneficial to add information on dispersion, absorption, transmission measurements of NCA and CA samples (single layers). This would also help to discuss the results.
Figure 4: Why is it so big?
5.Discussion
I think it is more a conclusion and should be revised.
E.g.
The shrinkage: what does it mean (influence) for production?
Page 6, line151 and 152: in case of CA lense the material is something like glass. In consequence I would expect similar LIDTs. If you have some measurements/inforamtion on chemical composition, n, k, strucutre you can discuss better.
Abstract, page 1, line 5 to 6: The sentence is difficult to understand
1. Introduction, page 1, line 24: LDW schould be also intriduced here for the first time.
2. Fabrication, page 3, line 69 and 70: The sentence is difficult to understand
3. LIDT Metrology, page 3, line 80: NCA used as reference (or similar) sound better than "control". "(test)" I would not mention -> sound like a clinical study
..., line 88: "represented" -> better use "as illustrated"
Author Response
Section 2:
Figure 1: As the figure is mentioned/introduced in section 1 and section 2 I would suggest to split it into two pictures (1) a and b for fabrication and 2) c for Testing -> include in fig 2 on page 3). What do you mean with delocalised regime and lens array in the picture?
In the eyes of the authors, splitting the figure introduces more confusion than clarity. Fig. 1 follows the experiment method from begining to the end.
Figure gives visual representation of an actual lens array and the delocalised regime illuminarion as an example.
Additional changes in caption were made.
Page 2, line 67: I would suggess to introduce the NCA and CA here -> is referred to ...
Fixed, thank you.
Page 3, line 69: (also in fig 1): Is it necessarry/important to the work to mention the darkening at 600°C?
Darkening explains the need for calcination in higher temperatures (1100C+).
- LIDT Metrology
Page 3, line 76: What do you mean with "image function"? Can describe in more detail
Lens ability to form an image of an object placed under microcope illumination
Figure 3, figure descritption: not clear, should be revised
Fixed, thank you.
- Results
Page 4, line 100: I do not understand. In Figure 1 a) a NCA lense is shown?
Yes, moved the reference. Thank you.
Page 4, line 104 ff.: This section need a little bit more logical structure. It jumps between results for NCA and CA.
We do not see it illogical and would prefer leave it as it is, unless specified more of where the jump is seen?
Information given goes point by point comparing CA and NCA results.
Page 4, line 110 ff.: I think one point has to be taken into account is the refractive index (band edge) and the absorption as well as the microstructure of the material. In generall it would be beneficial to add information on dispersion, absorption, transmission measurements of NCA and CA samples (single layers). This would also help to discuss the results.
Currently, it is not possible to produce calcinated bulk SZ2080 samples large enough for such measurements to efficiently and reliably done, therefore direct comparison of material optical properties would not be wise in this work. We can, however, theorize it exhibiting similar characteristics to „classic“ Silica-Zirconia glass.
Figure 4: Why is it so big?
Shrunk to ½ size.
5.Discussion
I think it is more a conclusion and should be revised.
E.g. The shrinkage: what does it mean (influence) for production?
The shrinkage factor must be taken into account for designing and including pre-compensation constant for the CAD model to be manufacturing as actually required object, however this phenomenon is out of the scope of this article.
We agree with the Reviewer that the section should be considered as Conclusion. The current Conclusions are just a restatement of formal numeric results and therefore is superfluous. Therefore, we renamed the Discussion section to Conclusions and removed the “Summary” from Conclusions.
We took the result Discussion elements from the section above, where we listed the results and properly included them in Discussion, and separated the Conclusions elements to Conclusions.
Page 6, line151 and 152: in case of CA lense the material is something like glass. In consequence I would expect similar LIDTs. If you have some measurements/inforamtion on chemical composition, n, k, strucutre you can discuss better.
Previous results of SZ2080 LIDT are given in [24,25,30]. We do not have any additional information on calcinated SZ2080 properties yet, it is a matter of current research.
Comments on the Quality of English Language
Abstract, page 1, line 5 to 6: The sentence is difficult to understand
Rewritten accordingly making it a two sentence claim for easier readability.
- Introduction, page 1, line 24: LDW schould be also intriduced here for the first time.
Fixed, thank you.
- Fabrication, page 3, line 69 and 70: The sentence is difficult to understand.
Fixed, thank you.
- LIDT Metrology, page 3, line 80: NCA used as reference (or similar) sound better than “control”. “(test)” I would not mention -> sound like a clinical study …, line 88: “represented” -> better use “as illustrated” .
Fixed, thank you.
Once again we thank the Editor ant both of the Reviewers for the accurate comments and insights, which helped significantly to improve the quality of the manuscript.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear Authors
Thank you for the revised manuscript and the explanations. Than I am looking forward to see the results of future investigations on this topic.
Best regards
