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Cited by 11Advanced Surface Polishing TechniquesSurface Roughness and Optical MeasurementsAdvanced optical system design

Smoothing tool design and performance during subaperture glass polishing

Open access
Suratwala, T., Tham, G., Steele, R., Wong, L., Menapace, J., Ray, N., Bauman, B.·2023·Applied Optics
DOI 10.1364/ao.482739
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Abstract

During subaperture tool grinding and polishing, overlaps of the tool influence function can result in undesirable mid-spatial frequency (MSF) errors in the form of surface ripples, which are often corrected using a smoothing polishing step. In this study, flat multi-layer smoothing polishing tools are designed and tested to simultaneously (1) reduce or remove MSF errors, (2) minimize surface figure degradation, and (3) maximize the material removal rate. A time-dependent convergence model in which spatial material removal varies with a workpiece-tool height mismatch, combined with a finite element mechanical analysis to determine the interface contact pressure distribution, was developed to evaluate various smoothing tool designs as a function of tool material properties, thicknesses, pad textures, and displacements. An improvement in smoothing tool performance is achieved when the gap pressure constant, h ¯ (which describes the inverse rate at which the pressure drops with a workpiece-tool height mismatch), is minimized for smaller spatial scale length surface features (namely, MSF errors) and maximized for large spatial scale length features (i.e., surface figure). Five specific smoothing tool designs were experimentally evaluated. A two-layer smoothing tool using a thin, grooved IC1000 polyurethane pad (with a high elastic modulus, E pad =360MPa), thicker blue foam (with an intermediate modulus, E foam =5.3MPa) underlayer, and an optimized displacement ( d t =1mm) provided the best overall performance (namely, high MSF error convergence, minimal surface figure degradation, and high material removal rate).

AI snapshot

Written from the paper’s full text.

TL;DR

The paper develops a time-dependent convergence model and finite element analysis to design flat multi-layer smoothing tools for subaperture glass polishing, balancing mid-spatial frequency (MSF) ripple removal, surface figure degradation, and material removal rate. Experiments with five tool designs show a grooved IC1000 pad on blue foam at an optimized displacement of 1 mm gives the best overall performance.

Key findings

  • The gap pressure constant (h) should be minimized at small spatial scale lengths (MSF ripples) and maximized at large spatial scale lengths (surface figure). In model calculations, h = 5 µm gave 98.5% ripple convergence, while h = 410 µm gave only 4.8% convergence for longer-scale features.
  • FEA showed h increases with foam modulus and spatial scale length, and decreases with pad modulus, pad thickness, and foam thickness. Adding grooves changed h little at small scale (6 to 7–8 µm) but increased it at long scale (120 µm to >300 µm).
  • Material removal scaled with foam underlayer modulus: blue foam (5.3 MPa) tool removed 1.6 µm (7.1 mm³/hr); yellow foam (2.2 MPa) tools removed 0.9 or 1.1 µm (4.0 or 4.9 mm³/hr); black foam (0.13 MPa) tools removed 0.25 or 0.6 µm (1.1 or 2.7 mm³/hr). At Rt = 1000 rpm, tool D removal decreased from 1.1 to 0.5 µm (2.2 mm³/hr).
  • Ripple reduction was best for grooved IC1000 blue foam (E) with 1% rms remaining, followed by grooved IC1000 yellow foam (D) with 3% rms; pitch/felt yellow foam (A) left 26% rms. Tool E repeated five times gave average figure degradation rsf = 138 ± 45 nm/µm.

Methods

  • Design: a time-dependent convergence model based on workpiece–tool height mismatch and the Preston equation, combined with 2D semi-infinite static elastic FEA (COMSOL Multiphysics) to determine interface pressure distributions and an empirical gap pressure constant as a function of pad/foam modulus, thickness, feature amplitude/spacing, and tool displacement.
  • Experiments: five 25 mm diameter smoothing tools (A–E) were tested on a Satisloh SPS-200 CNC polishing machine using 100 mm diameter fused silica workpieces (Corning 7980) and CeO2 slurry (Cerox1663, Baume 9, ~100 ml/s). Baseline conditions were dt = 0.5 mm, Rt = 250 rpm, tilt 0°, Vf = 62 mm/min, pitch step 0.5 mm, n = 1; polishing time was 67 min.
  • Three performance tests: material removal rate (half-polished flat workpieces, Michelson interferometer), MSF ripple reduction (pre-created ripples ~5 µm PV, ~300 µm spacing; measured by 3D coherence scanning interferometry), and figure degradation (Alvarez freeform with 1.2 mm PV and 47 µm/mm max slope; stitching interferometer).

Limitations

  • Stated: data are not publicly available at this time but may be obtained from the authors upon reasonable request. Also stated: increasing tool displacement beyond 1.0 mm led to tool delamination during polishing, indicating a practical displacement limit.
  • Evident from the text: only five specific tool designs were tested, on one glass type (fused silica), one polishing machine, and one slurry; the model assumes a linear pressure drop with gap and constant Preston/friction terms except pressure, and the time-average velocity varied spatially by 5.9% in one linear direction.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1364/ao.482739

Cites

38 of 38 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

9 of 41 cited sources checked · 2 supported · 0 flagged · accuracy not yet measured

  • Findingcitation
    § 2. Experimental · p. 6

    The lack of rotation of the workpiece results in the generation of ripples (typically 5 μm high and 100's of microns apart) on the surface that are analogous to MSF ripples that can occur during grinding.

    “The lack of rotation of the workpiece results in the generation of ripples (typically 5 µ m high and 100's of microns apart) on the surface that are analogous to MSF ripples that can occur during grinding [37].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [37] Preston, 1922, Trans. Opt. Soc. source

      The discussion of smoothing (section I49; page not given) says that abrasive grains can produce chatter cuts on glass, supporting only the general point that abrasion can leave repeated surface markings. The copy does not link those markings to a lack of workpiece rotation, identify them as analogous to MSF ripples, or give the claimed 5 µm height and hundreds-of-microns spacing. The much finer chatter-flaw spacing reported in Section 11, Etch Patterns, does not substantiate those dimensions. (LLM, conf=0.83)

      Experimental — accuracy not yet measured
  • Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    The flat two-layer smoothing tool has high pressures at the workpiece peaks both at small and large spatial scale lengths.

    “The resulting pressure distribution is shown in Fig. 9a which shows that the flat twolayer smoothing tool has the expected high pressures at the workpiece peaks both at small (lefttop) and large (left-bottom) spatial scale lengths.”
    Quote in the paperSubstantial claim
  • Findingcitation
    § 2. Experimental · p. 5

    Using a vector based kinematics analysis described previously, the time average velocity, using the parameters described above with full overlap the tool diameter, varies spatially only 5.9% in one of the linear direction.

    “Using a vector based kinematics analysis described previously [36], the time average velocity, using the parameters described above with full overlap the tool diameter, varies spatially only 5.9% in one of the linear direction.”
    • Also stated in: § 3.1.1 Time-dependent pressure convergence model · p. 7 · plain
      “Because the time average velocity variation in the kinematics is small (see Fig. 2)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [36] Suratwala, 2014, J. Am. Ceram. Soc. source
  • Findingown data
    § 4. Conclusions · p. 18

    An elastic mechanic FEA analysis determined the pressure distribution and gap pressure constant (the rate of change in interface pressure with workpiece-tool height mismatch) for various single-layer and two-layer smoothing tool designs.

    “Using an elastic mechanic FEA analysis, the pressure distribution and gap pressure constant (describing the rate of change in interface pressure with change in workpiece-tool height mismatch) has been determined for various single layer and two-layer smoothing tool designs.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3.1.2 Gap constant determination h · p. 10

    The empirical relationship (Eqs. 4-5) can describe the gap pressure constants over the range of parameters evaluated.

    “The following empirical relationship can describe the gap pressure constants over the range of parameters evaluated as:”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The sinusoidal bumps used in the FEA are representative of linear ripples often observed on optical workpieces.
  • Classified as probably not a substantial claim. 11
  • May combine two claims. 34
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 4

    Existing models on the removal of MSF ripples are based on concepts similar to the workpiece-tool mismatch mechanism described above.

    “Existing models on the removal of MSF ripples are based on concepts similar to the workpiece-tool mismatch mechanism described above [26-29].”
    Quote in the paperNot a substantial claim1 of 4 sources checked
    • cites [26] Jones, 1995, Appl. Opt. source
    • cites [27] Mehta, 1999, Proc. SPIE source
    • cites [28] Nie, 2014, Appl. Opt. source
    • cites [29] Kim, 2010, Opt. Express source

  • May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    The smoothing mechanism is based on the workpiece-lap (or workpiece-tool) mismatch and the convergence concept, where greater pressure (and hence material removal) occurs at the taller surface height locations on the workpiece relative to the lower surface height locations, resulting in a reduction of overall height variations with polishing.

    “The smoothing mechanism is based on the workpiece-lap (or workpiece-tool) mismatch and the convergence concept, where greater pressure (and hence material removal) occurs at the taller surface height locations on the workpiece relative to the lower surface height locations resulting in a reduction of overall height variations with polishing[21-24].”
    Quote in the paperSubstantial claim1 of 4 sources checked
    • cites [21] Suratwala, 2010, J. Am. Ceram. Soc. source
    • cites [22] Suratwala, 2021, Appl. Opt. source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
    • cites [23] Suratwala, 2012, Int. J. Appl. Glass Sci. source
    • cites [24] Burge, 2001 source

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    The general approach to minimizing MSF errors in the final workpiece during fabrication is to develop processes that minimize the creation of MSF errors during surface figure correction and/or to reduce MSF errors post surface figure correction using a smoothing polishing process.

    “The general approach to minimizing MRF errors in the final workpiece during fabrication is to: 1) develop processes that minimize the creation of MSF errors during surface figure correction (such as optimized rastering patterns[12-14], tool size selection, and tool process parameters[15, 16]); and/or 2) reduce MSF errors post surface figure correction using a smoothing polishing process[17-20].”
    Quote in the paperSubstantial claim3 of 9 sources checked
    • cites [12] Cheng, 2016

      Not checked in the free run.

    • cites [13] Dong, 2018, Appl. Opt. source
    • cites [14] Beaucamp, 2021, Opt. Express source
    • cites [15] Lin, 2015, Opt. Eng. source
    • cites [16] Tuell, 2002, Opt. Eng. source
    • cites [17] Kim, 2010, Opt. Express source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
    • cites [18] Li, 2019, Appl. Opt. source
    • cites [19] Nie, 2014, Proc. SPIE source
    • cites [20] Suratwala, 2018 source

      Split into 2 atoms — 0 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 2 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 1. Introduction · p. 4

    Various tool types have been developed including multilayer elastic tools, viscoelastic tools (like Newtonian fluids), semi-flexible tools (e.g. thin metal layer), viscoplastic (pitch) tools, and mechanically driven tools.

    “Various tool types have been developed including multilayer elastic tools, viscoelastic tools (like Newtonian fluids) [18, 30, 31], semi-flexible tools (e.g. thin metal layer) [17, 19, 20], viscoplastic (pitch) tools [19, 27, 28, 32], and mechanically driven tools[33].”
    Quote in the paperNot a substantial claim3 of 9 sources checked
    • cites [18] Li, 2019, Appl. Opt. source
    • cites [30] Zhu, 2022, CIRP Ann. source
    • cites [31] Song, 2017, Photonics Sens. source

      The Introduction describes a rigid conformal lap using a visco-elastic fluid, supporting this source's citation for a viscoelastic tool. But it calls the fluid non-Newtonian, as does Section 2; it does not support the parenthetical example of a Newtonian fluid. The other tool types have separate citations in the citing sentence. (LLM, conf=0.89)

      Experimental — accuracy not yet measured
    • cites [17] Kim, 2010, Opt. Express source

      The Introduction describes a visco-elastic polishing tool, supporting the cited tool category. But it specifies that the RC lap uses a non-Newtonian fluid, not a Newtonian fluid as the citing sentence suggests. The other tool categories have separate citations in the citing sentence and are not assessed here. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [19] Nie, 2014, Proc. SPIE source
    • cites [20] Suratwala, 2018 source

      The Organization (p. 4) lists viscoelastic/viscoplastic lap response, supporting the existence of viscoplastic polishing laps. The Organization (p. 6) separately lists pitch button blocking, but our copy does not identify pitch as a viscoplastic polishing tool; that example is not established by this source. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
    • cites [27] Mehta, 1999, Proc. SPIE source
    • cites [28] Nie, 2014, Appl. Opt. source
    • cites [32] West, 1994, Appl. Opt. source

  • May combine two claims.

    Findingreasoning
    § 3.2 Smoothing tool performance · p. 14

    Material removal amount or rate scaled with the modulus of the thicker foam underlayer: highest for the blue foam (5.3 MPa) tool at 1.6 μm (7.1 mm3/hr), followed by the yellow foam (2.2 MPa) tools at 0.9 or 1.1 μm (4.0 or 4.9 mm3/hr), and then the black foam (0.13 MPa) tools at 0.25 or 0.6 μm (1.1 or 2.7 mm3/hr).

    “In general, the removal amount or rate scaled with the modulus of the thicker foam underlayer, highest with the blue foam (5.3 MPa) tool with 1.6 µ m (or 7.1 mm 3 /hr), followed by the yellow foam (2.2 MPa) tools with 0.9 or 1.1 µ m (4.0 or 4.9 mm 3 /hr), and then the black foam (0.13 MPa) tools with 0.25 or 0.6 µ m (1.1 or 2.7 mm 3 /hr).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 3.2 Smoothing tool performance · p. 15

    For smoothing tool (D) at a higher tool rotation rate of 1000 rpm, the removal decreases from 1.1 to 0.5 μm (2.2 mm3/hr) despite an expected increase due to the 4x increase in relative velocity.

    “Interestingly, the removal decreases from 1.1 to 0.5 µ m (2.2 mm 3 /hr) despite an expected increase due the 4x increase in relative velocity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3.1.1 Time-dependent pressure convergence model · p. 8

    In the time-dependent convergence model, a small gap pressure constant (5 μm) results in rapid ripple convergence (98.5% convergence) whereas a large gap constant (410 μm) results in little change in surface shape (4.8% convergence).

    “The small gap pressure constant ( = 5 µ m) results in rapid ripple convergence (98.5% convergence) whereas the large gap constant ( = 410 µ m) results in little change in surface shape (4.8% convergence).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    A higher modulus single-layer tool results in a lower h at small spatial scale lengths (desired) but at the expense of a lower than desired h at larger spatial scale lengths.

    “A higher modulus single-layer tool results in a lower at small spatial scale lengths (desired) but at the expense of a lower than desired at larger spatial scale lengths.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Findingown data
    § 3.2 Smoothing tool performance · p. 18

    This tool had the highest modulus top layer, a grooved top layer, and an intermediate modulus bottom layer, used at the optimum displacement.

    “This tool had the highest modulus top layer, a grooved top layer, and intermediate modulus bottom layer used at the optimum displacement.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    A lower modulus single layer tool results in a higher h at larger spatial scale lengths (desired), but at the expense of higher than desired h at lower spatial scale lengths.

    “Similarly, a lower modulus single layer tool results in a higher at larger spatial scale lengths (desired), but at the expense of higher than desired at lower spatial scale lengths.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Findingreasoning
    § 3.1.3 Smoothing tool design optimization · p. 12

    A two-layer smoothing tool with the correct tool design enables better smoothing tool performance leading to both smaller h at small spatial scale lengths and higher h at larger spatial scale lengths.

    “In contrast, a two-layer smoothing tool with the correct tool design (see discussion below) enables better smoothing tool performance leading to both smaller at small spatial scale lengths and higher at larger spatial scale lengths.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Findingown data
    § 3.2 Smoothing tool performance · p. 17

    The same experiment was repeated 5 times, yielding an average rf of 138 ± 45 nm/μm.

    “the same experiment was repeated 5 times yielding average r f =138 ±45 nm/ µ m.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    At longer spatial scale lengths, the effective gap pressure constant increases from 120 μm to greater than 300 μm with the addition of grooves, which should further reduce the amount of surface figure degradation.

    “At longer spatial scale lengths, the effective increase, from 120 µ m to >300 µ m with the addition of grooves, h h h h which should further reduce the amount of surface figure degradation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 3.2 Smoothing tool performance · p. 14

    The similar notched IC1000 black foam tool (C) had a removal rate of 0.6 μm, which is more than double that of tool B despite having a similar tool design.

    “Initially this was surprising since the similar notched IC1000 black foam tool (C) had a removal rate of 0.6 µ m, which is more than double despite having a similar tool design.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3.2 Smoothing tool performance · p. 15

    Starting ripples on the fused silica surface typically have a peak-to-valley height of about 5 μm (or about 1 μm rms) and a spatial scale length of about 300 μm.

    “typically having a PV height of ~5 µ m (or ~1 µ m rms) and spatial scale length of ~300 µ m.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data
    § 3.1.1 Time-dependent pressure convergence model · p. 8

    The specific values in Fig. 4 are for the IC1000 pad on blue foam tool (E) determined from FEA simulations due to changes in spatial scale length (L=200 μm or L=30,000 μm).

    “The specific values are for the IC1000 pad on blue foam tool (E) determined from FEA simulations (discussed in h h Section 3.2.2) due to changes in the spatial scale length (L=200 µ m or L=30,000 µ m, respectively).”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Findingown data
    § 3.2 Smoothing tool performance · p. 15

    The different smoothing tools led to different overall removal rates, so the extent of material removal was different for each smoothing tool used.

    “Because the different smoothing tools led to different overall removal rates (refer to Fig. 10b), the extent of material removal was different for each smoothing tool used.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    The grooved two-layer smoothing tool has a more complex pressure distribution at large spatial scale lengths, with pressure peaks that do not always line up with the workpiece peaks.

    “However, the grooved two-layer smoothing tool has a more complex pressure distribution with pressure peaks that don't always line up with the workpiece peaks (right-bottom).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3.1.3 Smoothing tool design optimization · p. 12

    At small spatial scale lengths, the addition of grooves or notches leads to little change in the gap pressure constant from 6 to 7-8 μm, so ripple convergence should be similar.

    “At small spatial scale lengths, the addition of grooves or notches leads to little change in from 6 to 7-8 µ m, hence ripple convergence should be similar.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 1. Introduction · p. 3

    The phenomenon is time dependent as material is removed; the workpiece-tool mismatch will change and hence the pressure distribution will also.

    “Note that this phenomenon is time dependent as material is removed; the workpiece-tool mismatch will change and hence the pressure distribution will also.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 3

    Machine vibrations or non-smooth movements of the stage can cause MSF errors.

    “or by various machine vibrations or non-smooth movements of the stage[4, 5].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [4] Tinker, 2013, Proc. SPIE source
    • cites [5] Boerret, 2005, Proc. SPIE source

  • May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    MSF errors can cause detrimental effects on optical performance including increased small angle scatter, increased downstream modulation/intensification, and reduced image contrast.

    “MSF errors can cause detrimental effects on the optical performance including increased small angle scatter, increased downstream modulation/intensification, and reduced image contrast [6-11].”
    Quote in the paperSubstantial claim0 of 6 sources checked
    • cites [6] Tamkin, 2010, Appl. Opt. source
    • cites [7] Aikens, 1995, Proc. SPIE source
    • cites [8] Hull, 2012, Proc. SPIE source
    • cites [9] Forbes, 2015 source
    • cites [10] Noll, 1979, Opt. Eng. source
    • cites [11] Tamkin, 2010, Appl. Opt. source

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given
    § 3.2 Smoothing tool performance · p. 16

    An increase in displacement should increase the overall applied pressure (and hence material removal) and may or may not reduce surface figure degradation.

    “Increase in displacement should increase the overall applied pressure (and hence material removal) and may or may not reduce surface figure degradation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning
    § 3.2 Smoothing tool performance · p. 15

    The smoothing polishing runs were conducted using the same kinematics for each smoothing tool, and hence had the same polishing run times.

    “Note the smoothing polishing runs were conducted using the same kinematics for each smoothing tool, and hence had the same polishing run times.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given
    § 3.1.3 Smoothing tool design optimization · p. 11

    An ideal smoothing tool would have a small value of h at small spatial scale lengths (representing MSF errors), a large value of h at longer scale lengths (representing surface figure), and a high material removal rate to maintain short process times.

    “An ideal smoothing tool would have: 1) a small value of at small spatial scale lengths (representing MSF errors); 2) a large value of at longer scale lengths (representing surface figure); and 3) a high material removal rate to maintain short process times.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Study design and conductcitation
    § 3.2 Smoothing tool performance · p. 14

    The kinematics used for each experiment were largely kept the same, and analysis of the time average velocity distribution suggests uniform removal over the workpiece as long as a given workpiece location experiences the full set of tool contact overlaps.

    “The kinematics used for each of the experiments were largely kept the same, and the analysis of the time average velocity distribution suggests uniform removal over the workpiece as long as a given workpiece location experiences the full set of tool contact overlaps (see [36] for details).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [36] Suratwala, 2014, J. Am. Ceram. Soc. source

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given
    § 1. Introduction · p. 4

    One challenge with time-dependent tools, such as viscoplastic or viscoelastic tools, is that its time response can often be slower than the relative velocity between the tool and workpiece, which can result in a delayed pressure response to the workpiece surface height being addressed.

    “One challenge with the time-dependent tools, such as viscoplastic or viscoelastic tools, is that its time response can often be slower than the relative velocity between the tool and workpiece. This can result in a delayed pressure response to the workpiece surface height being addressed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given
    § 3.2 Smoothing tool performance · p. 17

    To get a high material removal rate, higher pressures are desired, requiring a higher modulus underlayer.

    “However, to get high material removal rate, higher pressures are desired requiring a higher modulus underlayer.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Interpretationreasoning
    § 3.2 Smoothing tool performance · p. 14

    The interface pressure at a fixed tool displacement, and hence material removal rate, scales with the tool effective modulus.

    “Intuitively, this makes qualitative sense since the interface pressure (at a fixed tool displacement), and hence material removal rate, would scale with the tool effective modulus.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 3.1.1 Time-dependent pressure convergence model · p. 7

    The smaller the gap pressure constant, the larger the pressure change with mismatch and the greater the convergence rate (i.e., ripple removal).

    “The smaller the gap pressure constant, the larger the pressure change with mismatch and the greater the convergence rate (i.e., ripple removal).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data
    § 3.2 Smoothing tool performance · p. 15

    The results are consistent with the simulation results in Section 3.1, where smoothing tools with a high modulus top layer and a groove pattern can be effective at removing ripples (MSF errors).

    “These results are consistent with the simulation results discussed in Section 3.1 , where smoothing tools with a high modulus top layer and with a groove pattern can be effective at removing ripples (MSF errors).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given
    § 3.2 Smoothing tool performance · p. 18

    Optimization of the tool displacement dt can aid in both an improvement in material removal rate and a reduction in surface figure degradation.

    “Finally, optimization of the tool displacement, dt , can aid in both an improvement in material removal rate and reduction in surface figure degradation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductreasoning
    § 2. Experimental · p. 6

    The pitch step (xs=0.5 mm) is significantly smaller than the tool diameter of 25 mm; hence only workpiece surface locations that experienced 50 steps observed the full polishing intent of the polishing run.

    “Note the pitch step ( xs =0.5 mm) is significantly smaller than the tool diameter of 25 mm; hence only workpiece surface locations that experienced 50 steps (25 mm/0.5 mm) observed the full polishing intent of the polishing run.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning
    § 3.1.1 Time-dependent pressure convergence model · p. 8

    For the design of a specific smoothing tool, one desires to maximize convergence of midspatial scale length surface features (i.e., ripples) and to minimize the convergence of the longer spatial scale length features (i.e., surface figure); in other words, the smoothing tool should be locally (small spatial scale) stiff and globally (long spatial scale) compliant.

    “For the design of a specific smoothing tool, one desires to maximize convergence of midspatial scale length surface features (i.e., ripples) and to minimize the convergence of the longer spatial scale length features (i.e., surface figure). In other words, the smoothing tool should be locally (small spatial scale) stiff and globally (long spatial scale) compliant.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

  • May combine two claims.

    Interpretationown data
    § 3.2 Smoothing tool performance · p. 15

    Hydrodynamic forces dominate at higher rotation rates, decreasing friction at the interface and hence removal rates.

    “These results suggest that hydrodynamic forces dominate at the higher rotation rates decreasing the friction at the interface and hence removal rates.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation
    § 3.2 Smoothing tool performance · p. 14

    The untextured IC1000 pad surface is more prone to hydroplaning, which explains the lower removal rate of tool B compared to tool C.

    “We attribute this to the untextured IC1000 pad surface being more prone to hydroplaning.[39]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [39]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationnone given
    § 3.1.1 Time-dependent pressure convergence model · p. 7

    A larger gap leads to lower local strain of the tool and hence less stress at that location.

    “A larger gap leads to lower local strain of the tool and hence less stress at that location.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § Abstract: · p. 3

    Improvement in smoothing tool performance is achieved when the gap pressure constant is minimized for smaller spatial scale length surface features (namely MSF errors) and maximized for large spatial scale length features (i.e., surface figure).

    “Improvement in smoothing tool performance is achieved when the gap pressure constant, (which describes the inverse rate at which pressure drops with workpiece-tool height mismatch) is minimized for smaller spatial scale length surface features (namely MSF errors) and maximized for large spatial scale length features (i.e., surface figure).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The relative pressure distribution decays linearly with the workpiece-tool gap.
    • The authors state this as an assumption: For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.
38 of 38

  • The authors state this as an assumption.

    The relative pressure distribution decays linearly with the workpiece-tool gap.

    “One can write the relative pressure distribution as a function of the gap, assuming a linear decay in pressure with gap (see discussion in 3.1.2), as:”
    “Hence for simplicity of the model, a linear pressure drop gap constant was used (see Eq. 1).”

  • The authors state this as an assumption.

    For a given polishing process, the friction coefficient and Preston constant are constant (not spatially or time varying) except for the pressure distribution.

    “Because the time average velocity variation in the kinematics is small (see Fig. 2) and assuming for a given polishing process that the other terms (friction coeffient and Preston constant) are constant (not spatially or time varying) except for the pressure distribution, Eq. (2) can be then rewritten as:”

  • The paper relies on this without support.

    The sinusoidal bumps used in the FEA are representative of linear ripples often observed on optical workpieces.

    “Note the sinusoidal bumps are infinite in-and-out of the plane, representative of linear ripples often observed on optical workpieces.”

  • The paper relies on this without support.

    The mounting of the two-layer smoothing tool effectively acts as a three-layer smoothing tool accounting for the effective modulus of the fixed displacement spring mount.

    “Note the mounting of the two-layer smoothing tool effectively acts as three-layer smoothing tool accounting for the effective modulus of the fixed displacement spring mount.”

  • The paper relies on this without support.

    An ideal smoothing tool should maximize MSF ripple removal, minimize surface figure degradation, and maximize material removal rate.

    “An ideal smoothing tool aims to: 1) maximize MSF ripple removal (i.e., minimize at small spatial scale lengths); 2) minimize surface figure degradation (i.e., maximize at larger spatial scale length); and 3) maximize material removal rate (i.e., increase interface pressure magnitude and maintain good slurry transport).”
5 of 5

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Figure 6 cites the wrong source panel

    Minor

    Figure 6 says its gap pressure constants use data from Figure 4b, but Figure 4b is a calculated surface-height profile. The text identifies Figure 5b as the relative-pressure-versus-gap data used to determine those constants.

  • Figure 10 mislabels the grooved yellow-foam tool

    Minor

    The caption identifies the grooved IC1000 yellow-foam tool as (A), but the paper assigns that design to tool (D); tool (A) is the pitch/felt yellow-foam tool.

  • Figure 13 names an undefined tool F

    Minor

    The Figure 13 caption says the measurements used tools (E) and (F), whereas the results text says they used tools (D) and (E). The paper defines only tools (A) through (E).

3 of 3

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Authors
Suratwala, T., Tham, G., Steele, R., Wong, L., Menapace, J., Ray, N., & Bauman, B.
Affiliations
Lawrence Livermore National Laboratory (US)
Corresponding author
  • Suratwala, T.
  • Tham, G.
  • Steele, R.
  • Wong, L.
  • Menapace, J.
  • Ray, N.
  • Bauman, B.
ORCID
Venue
Applied Optics
Publisher
Optica Publishing Group
Published
2023-03-07
Volume
62
Issue
8
Pages
2061
ISSN
  • 0003-6935 (ISSN-L)
  • 1559-128X
  • 2155-3165
DOI
10.1364/ao.482739
OpenAlex
W4318693456
Semantic Scholar
9af751a0d4e8b95c0d11badb06bae6296209f657
Cited by
11
References
35
Citations by year
2026: 3 · 2025: 5 · 2024: 1 · 2023: 2
FWCI
1.20
Type
journal article
Language
en
Open access
Licence
Locations
  • Applied Optics (publishedVersion)
  • PubMed (publishedVersion)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
Funders
U.S. Department of Energy (DE-AC52-07NA27344, LLNL-JRNL-842775)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Advanced Surface Polishing Techniques
  • Physical Sciences › Engineering › Computational Mechanics › Surface Roughness and Optical Measurements
  • Physical Sciences › Engineering › Biomedical Engineering › Advanced optical system design
Keywords
mid-spatial frequency error, surface ripples, material removal rate, contact pressure distribution, polyurethane polishing pad, tool design optimization, finite element contact analysis

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-28.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-28.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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