Automated Lens Measurement System

Project # 05427

Team Members

Rhiannon Casale

John Spalding

Melissa Groginski

Frank Capristo

Paul Thompson

Matt Place

Presentation Overview

Introduction/Project Overview Summary of Senior Design I Fixture Development Testing Plan Testing Results System Recommendation Implementation Analysis Cost/Benefit Analysis Conclusions

Mission Statement

“To provide Bausch & Lomb with the most cost effective, non contact solution for accurately measuring the central thickness of a contact lens.”

Project Background

Current System – Rehder Gage– Mechanical contact – wet state, offline

– Gage R&R (TORIC) ~ 50% at + 20 microns

– Accuracy within + 2 microns

Desired Measurement Specifications– Gage R&R < 18% at + 10 microns

– Measurement accuracy of + 1 micron

– Cycle time < 1 second

Concept Research

In-house Testing of Units

Teleconferences/On-site Visits

Team Research

Final Decision

Meeting with B&L experts Further Investigation

Feasibility AssessmentEvaluation of Results

Summary of Senior Design I

22 Companies8 Companies

4 Companies2 Companies

6 Technologies

Desired Outcomes for Senior Design II

Design and create fixtures for device and lens positioning

Bring in and test demonstration units from top vendors

Wet/Dry correlation studyCost/Benefit analysisEvaluate manufacturing lines to develop an

integration plan

Systems Received for Testing

Micro-Epsilon – Dry, out of the moldFilmetrics – Dry, out of the moldLumetrics – Dry, in the moldPanametrics – Wet, in inspection water cell

Fixture Design Challenges

Focal length within 125 microns (0.005 inches) Centration of lens within 50 microns (0.002 inches)

SolidWorks Models

Micro-Epsilon

Panametrics

Filmetrics

Fixturing

Testing Performed

Gage R&R’sMeasurement Verification

- Per lens specification

- Using Rehder GaugeDry/Wet Correlation

Operator Gage R&R

Why?– Means to compare outcomes to old system– Originally it was going to also be used as an off-

line station

When system implemented on-line the Gage R&R percentage will only become better as the operator percentage will not be included anymore

Gage R&R Percentage Definition Repeatability: Gage Error Reproducibility: Operators and Operators*Parts B&L Spreadsheet Verified with Minitab

– The results are given as a percentage

– R&R Variance:

– Study Variation:(5.15 is a constant that estimates the width of the interval to cover 99% of the

process.)

– Percent Gage R&R:

)*,,(& POPORVarianceR

*15.5tionStudyVaria

Tolerance

tionStudyVariaReRPercentGag &

Gage R&R Procedure

10 lenses were measured in a random order by 3 operators.

Each operator measured the 10 lenses 3 timesThe data from the 90 measurements was

entered into the B&L Gage R&R spreadsheetThe R&R percentage was calculatedToric and Bifocal lenses utilized

Testing Results: Micro-Epsilon

Preliminary Gage R&R Results (@ +/- 10 µm):Trial 1: CWT - 46%Trial 2: CWT - 36%Trial 3: CWT - 34%Trial 4: CWB - 8%

Modified fixture Gage R&R Results (@ +/- 10 µm):Trial 5: CWT - 18%Trial 6: CWT - 14%

Testing Results: Lumetrics

Gage R&R Results (@ +/- 10 µm):

Trial 1 : CWT - 11%

Trial 2 : CWT - 6%

Trial 3 : CWB - 8%

Panametrics/Filmetrics

Panametrics – System failed to meet project requirements– Unable to perform Gage R&R

Filmetrics

Gage R&R Results (@ +/- 10 µm):

Trial 1 : CWB - 3%

Trial 2 : CWT – Incapable

Dry/Wet Correlation

Procedure:– Measured in the mold w/Lumetrics– Lenses processed through dry-release– Measured dry lenses with Filmetrics system– Hydrate lenses– Measured on Rehder gage (current system)

Dry/Wet Correlation

Number of Lenses:

- 135 lenses across 9 SKUs measured in each state

- Lot sizes calculated to obtain a 99% confidence level

Verified dry lens measurement systems’

accuracy

Correlation Results

Correlation provides a viable model Results calculated with and without lot 7* R2 value of .9997 obtained not including lot 7*

* Lot 7 represents the worst case SKU for measuring central thickness. The correlation broke down when including lot 7 due to the extremely high Gage R&R on the current wet system.

Correlation ResultsDry - Wet Correlation Data Averages

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7T 7Z HF HE HD HC HB HA 7A

SKU

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ess

Val

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Lumetrics

Wet Rehder

Correlation ResultsDry To Wet Correlation Using Averages (without Lot 7)

R2 = 0.9997

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Lumetrics (um)

Reh

der

(u

m)

Recommendations

Lumetrics Parallel path with Micro-Epsilon

Measurement System Summary

SYSTEM R&R (CWB) R&R (CWT) SYSTEM COST PER LINE COST

Lumetrics 8% 6% $60,000 $ 9 - 60 K

Micro-Epsilon 8% 14% $17,000 $17,000

Filmetrics 3% N/A $17,000 $17,000

Implementation Bench top system No cost benefit to bench top

system

Implementation Device Placement

Fixture Design

Implementation

Calibration & Maintenance- Self Calibrating- Optical Cleaning when Necessary

- Surge Protection

PLC Interface- Continuous Measurement

- No Decision Making

- Real Time Remote Control and Data

Cost/Benefit Analysis

Potential Cost Reduction ~ 1-2% per lensLumetrics

– Return on Investment < 12 months

Micro-Epsilon– Return on Investment < 6 months

Increase in process control further reduces ROI time

Actual Outcomes for Senior Design II

Design and create fixtures for device and lens positioning

Bring in and test demonstration units from top vendors

Wet/Dry correlation studyCost/Benefit analysisEvaluate manufacturing lines to develop an

integration plan

Project Challenges

Lengthy Research PeriodVendor Lead TimesLens Fixturing TolerancesSetup and OptimizationVendor Support and CapabilityCorrelation Study LogisticsDevice Sensitivity

Project Stewardship

Purchase Lumetrics SystemFabricate Line FixtureInstall System and Collect Preliminary DataExecute Integration PlanValidate on R&D LineTransfer to Manufacturing

Thank You

Bausch & LombBill Appleton – Project CoordinatorRyan Williams – Project SponsorDave Martz – Metrology SupportKevin Beebe – Process SupportJohn Giallombardo – StatisticianProf. Esterman – R.I.T. Mentor Prof. Stiebitz – R.I.T. Coordinator

Questions

Any further questions?

Backup Slides

Process Flow Chart

Casting / Cure

Release

Hydration

Inspection

Packaging

Molding

Key Senior Design I MilestonesTask Finish Date

Needs Assessment Fri 12/17/05

Research Compilation and Review Thu 1/6/05

Vendor CDA Agreements Wed 1/19/05

Peer Presentation Fri 1/28/05

Feasibility Assessment Tue 2/8/05

Vendor Selection Summit Wed 2/9/05

Sample Testing / Capability of Vendors Thu 2/11/05

B&L Presentation Wed 2/16/05

Preliminary Design Packet Thu 2/17/05

Order Demo Systems Fri 2/18/05

PDR Presentation Fri 2/18/05

Possible Points of Integration

Dry State: In the assembled mold After mold de-capping After lens is released from mold

Wet State: During cosmetic inspection In blister package

Damage from Lens Handling

O-ring Signature Extraction Tray Marks Tweezers Mark

Judging criteriaRequirements Document

Weighting criteria5 = Most Important1 = Least Important

Scoring1 = Not quite able to meet needs3 = Exceeds needs

Feasibility

Feasibility Matrix

Correlation

Dry - Wet Correlation Data

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=

Data Points

Th

ickn

ess

Val

ue

Lumetrics Wet Rehder

Example Show ing Process Variability

Example Show ing Difference in Gage R&R

Cost Research

– Research was done to identify what the overall cost is to actually make the lens.

– Cost was broken down by each stage of the lens making process.

– The cost of material and operator were gathered.

– If the apparatus was eventually integrated into the line as an automated system, in order to cost justify the equipment such costs would need to be known.

Product Specification Research (Cont.)

Definitions:DF – Degrees of FreedomSS – Sum of SquaresMS – Mean SquareF – F-Valuea – Number of partsb – Number of operatorsn – Number of replicatesx-bar i.. – Mean for each partx-bar… - Grand Meanx-bar .j. – Mean for each operatorxijk – Is each observationxij. – Is mean for each factor level

Source DF SS MS F

Part a-1 b*n* Σ(x-bar i.. - x-bar…)2 SS Part / DF PartMS Part / MS Part*Operator

Operator b-1 a*n* Σ(x-bar .j. - x-bar…)2 SS Operator / DF OperatorMS operator / MS Part*Operator

Part*Operator

(a-1)*(b-1)

SS Total - (SS Part+SS Operator+SS Repeatability)

SS (Part*Operator) / DF (Part*Operator)

MS Operator*Part / MS Repeatability

Repeatability n-(a*b) ΣΣΣ(xijk - x-barij.)

2SS Repeatability / DF Repeatability  

Total n-1 ΣΣΣ(xijk - x-bar...)2    

Anova Table:

ANOVA Table Equations and Abbreviation Definitions

Variance and Standard Deviation

parts ofNumber * trialsofNumber

Part*Operator MS -Operator MSO

parts ofNumber * trialsofNumber

Part*Operator MS -Part MSP

parts ofNumber * trialsofNumber

ityRepeatabil MSPart *Operator MS* PO

)*,,(& POPORVarianceR

Variance: (MS is the mean square) Standard Deviation (SD):

O = √Operator Variance

P = √Part Variance

O*P = √Operator*Part Variance

R&R = √R&R Variance

*15.5tionStudyVaria

Tolerance

tionStudyVariaReRPercentGag &

Study Variation:

Percent Gage R&R:

(5.15 is a constant that covers 99% of the process.)

Study Variation and Percent Gage R&R Calculations

Experimentation Plan

Small initial trialBased on results, large trial, or halt trialsGauge R&RDOE as necessary

Calibration & Maintenance

Sensor is self calibrating (laser wavelength)Telecommunications grade 15-20 yearsCleaning Lens and Fiber Optic cablesSolid state components

PLC

National Instruments Drivers and SupportContinuous OperationNo Triggering or Nominal Values Fed to

DeviceAll Decisions made by PLCReal Time Control

Importance of Central Thickness

Optical properties

Durability

Comfort

Desired Process

Non-contact methodAutomated and fully integrated into lineNo manual, non-value added laborIncreased sampling rateNo discarding of good lenses after

measurement is performedMeasurement performed at an earlier stage of

production

Requirements of New Process

Non-Contact method of measurement Measure thickness range of 20 – 250 μm Measurement tolerance of ±10 μm Gauge R&R of ≤ 18% User Interface PLC Interface Plan Extensibility to future products

Concepts Researched

MechanicalVision SystemCapacitanceLaser TriangulationLaser AutofocusOpticalUltrasonic

Patent Search

13 related patents foundVisual Inspection SystemsLens ProductionContact Methods

No conflictsKey Words:

Thickness MeasurementThin FilmsContact lenses

Beta Laser Mike: – transmit and receive laser– Focal diameter too large for the application – Only good for flat applications

FRT of America: – They were not confident they could measure a curved surface such as a

contact lens.

MicroPhotonics: – Could only measure up to 50 microns

SolveTech: – Capacitive method – Requires a much larger spot size than required– Develop fixture to position the lens accurately between two plates – Separation distance to small

Eliminated Companies

Lumetrics (Cont.)

Possible install locations: Before mold separation Immediately before/after lens release from mold

Possible install locations: Immediately before/after lens release from mold Before the lenses are placed on the trays

Micro-Epsilon (Cont.)

Company Research

Lumetrics Keyence Elektrophysik FRT of America Mission Peak Optics Micro-Photonics Filmetrics Thermo Electron

Corp. ABB Adetech Onosokki

Lumetrics Mission Peak Optics Filmetrics MTI Instruments LMI Technologies, Inc. Micro-Epsilon ORYX Panametrics

Long List Short List MTI Instruments Inc. LMI Technologies Micro-Epsilon Beta Laser Mike ORYX Panametrics AccuSentry Norman N. Axelrod and Associates Dr. Schenk Inspection Systems Optical Data Associates, LLC. Solve TECH Inc

Keyence: – Device incapable of measuring the size and accuracy required

AccuSentry: – camera or vision system

– Entire concept of a vision system discarded due to the current lack in

adequate technology. Norman N. Axelrod and Associates:

– Do not sell a specific technology

– On-site visit , analyze the problem, and custom develop a solution. Adtech, ABB and Thermoelectron:

– No response when contacted

Eliminated Companies

Contact Lens Quick Reference Guide– Research was completed to create a reference guide for Bausch &

Lomb’s contact lens specifications.

– The specifications include:• Product line

• Lens type

• Monomer used

• Diameter and tolerance of the lenses

• Wet central thickness range and tolerance of the lenses

• Sagittal depth range and tolerance of the lenses

• Power range of each lens

• Refractive index of each lens

• If the lens is tinted

• Finished Product Specification

Product Specification Research

Radius of curvature– During research the radius of curvature (base curve) was questioned by

some of the vendors as this could potentially pose a problem in obtaining the central thickness measurement.

– This is another area where experts at Bausch & Lomb were able to inform the team of the dimension.

– Due to proprietary information this measurement may not be released.

Mold Information

– During the early stages of the project the mold material was introduced as Polypropylene and PVC depending on which contact lens it will contain.

– The refractive index is unknown at this point for any of the molds, but is being investigated in one of Bausch & Lomb’s labs.

Product Specification Research (Cont.)

Dr. Schenk inspection systems:– Sell products to measure thin films

– All products are meant to be installed on a high speed manufacturing line

– Take a measurement based on the profile view of the thin film

Optical Data Associates, LLC:– Specializes in high precision inspection of various components for their

optical properties

– This company is just a testing firm and therefore would not be able to help

or sell any technology that would meet the needs of the application.

Onosokki:

– Contact method systems for measurement

Eliminated Companies

Several patents were found that are within the realm of the given application. The topics varied from a contact probe that measured the actual thickness of a contact lens, other technologies used in taking measurements of a contact lens, to automated visual inspections of a contact lens. Since the application that is being dealt with is more process oriented on the measurement of the central thickness of a contact lens the patents are not being infringed upon by our application.

Patent Search

Patent number 4,665,624 – deals with a soft contact lens analyzing apparatus.

– This apparatus utilizes a fixturing device and several measurement scales to determine the diameter, sagittal depth and central thickness of a contact lens. All of the scales use probes that must come into contact with the actual lens.

– A mechanical, contact system which is not what our application calls for.

Patent number 4,403,420 – Digital gauge for measuring the sagittal depth and thickness of a lens, and the

related systems and methods

– This method involves a fixturing device and several linear encoders to measure the diameter, sagittal depth and central thickness of a lens. Each of the encoders is connected to some type of probe that needs to come into contact with the lens.

– A mechanical contact system in which our application will not infringe on.

Patent Search (Cont.)

Patent number 6,134,342: – Visual inspection method and apparatus for a contact lens.

– The method described is automated. The visual inspection system is looking for defects such as foreign material, scratches, breakage and so forth.

– No quantitative dimensional measurements performed and therefore does not have to do with our application.

Patent number 6,765,661:– A lens (such as contact lens) inspection method.

– This system looks for such flaws as tears or surface defects.

– No quantitative dimensional measurements preformed and therefore our application will not infringe with this patent.

Patent Search (Cont.)

Patent number 6,490,028: – Variable pitch grating for diffraction range finding system

– What is described is a very precise method to determine the range or distance from a reference point to an object. Utilizing a variable pitch grating does this.

– This system uses a completely different methodology than any of the apparatuses

the team has evaluated for the given application.

Patent number 6,815,947: – A method and system for thickness measurements of thin conductive layers

– This system utilizes an electrically conductive method known as eddy current. Extremely thin films that also have conductive properties are the only applicable item that may be measured using this system.

– Due to its limitations, the team ruled out this technology initially. None of the systems being evaluated use this or any related technology.

Patent Search (Cont.)

Patent number 6,847,458: – A method and apparatus for measuring the shape and thickness

variation of polished opaque plates

– In this system dual interferometers are used. One is placed on each side of the plate to perform its surface mapping and other calculations. Since the system is attempting to measure opaque plates two interferometers must be used.

– This system is different from any of the researched systems that have been evaluated because it is a dual interferometer system. All of the systems researched used only one interferometer.

– Also, this is for measuring opaque substances, as our application is to measure optically clear lenses.

Patent Search (Cont.)

Patent number 6,822,745: – Optical systems for measuring form and geometric dimensions of precision

engineered parts

– This patent does describe a similar technology that we will be utilizing. However, it describes the specific equipment and not the overall process of the measurement. Whichever piece of equipment that is decided upon to use in our application, should be protected by that respective companies patents.

– Other than that, no process issues are present that would violate this patent.

Patent number 6,791,691: – A measuring method that uses attuention in total reflection

– This patent describes a similar technology that we will be utilizing. Furthermore, it describes the specific equipment and not the overall process of measuring the object. That respective companies patent should protect whichever piece of equipment the team decides to use in our application.

– No process issues are present.

Patent Search (Cont.)

Patent number 6,301,005: – Inspection system for optical components

– This system contains a device to hold the optical component into place. It has the means to inspect the optical component for any apparent defects.

– No quantitative dimensional measurements are taken into account thus, compared to our

application is not the same and will not infringe.

Patent number 6,791,696: – An automated optical measurement apparatus and method

– This patent describes the method to measure lens properties, such as central thickness, utilizing a wavefront analysis.

– None of the technologies researched involve this type of technology. For this reason, our application will not infringe on this patent

Patent Search (Cont.)

Patent number 5,206,076: – A self aligned manufacturing system and method– This method does not pertain to the metrology of contact lenses. It describes a

method on how to actually produce contact and intra-ocular lenses. – Since this is describing the manufacturing process and not a measurement

process our application does not conflict.

Patent number 6,775,003: – Apparatus and method for total internal reflection spectroscopy– This also describes a similar technology that is being evaluated. Again,

although it has a similar technology it does not describe the process. – Therefore, the researched technologies respective companies patent should

protect the equipment in the end that the team decides to put into use. – No process issues are present.

Patent Search (Cont.)