Annoni, M.

Baruffi, Federico

Calaon, Matteo

Loaldi, D.

Parenti, P.

Quagliotti, Danilo

Tosello, Guido

The evaluation of an adequate and robust measuring strategy, for roughness assessment of polymer Fresnel lenses is put under assessment. An ‘on-sample’ measurement noise, is evaluated using a laser confocal microscope (OLYMPUS © Lext). Secondly, the lowest-noise roughness measuring procedure, on an injection compression moulded (ICM) Fresnel lens, is defined. A set of two different objectives is considered, i.e. a standard series (SO), against a long working distance one (LWD); two different magnifications objectives, 50x and 100x and the use or not of a dark environment. The noise evaluation is performed by comparing ‘on-sample’ noise with the one calculated on an optical flat. Noise is investigated by means of established methods, i.e. subtraction and averaging methods. Afterwards, the lowest-noise analysis is structured following a 23 full factorial experimental planning, whose factors are measuring working distance, objective magnification and room lighting. The result confirms a strong difference of noise, using the considered objectives. The most interesting result is that the performance of SO 50x objective is better than LWD 100x

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 18, 2017Laser confocal microscope noise evaluation on injection compression moulded (ICM)transparent polymer Fresnel lensesLoaldi, Dario; Calaon, Matteo; Quagliotti, Danilo; Baruffi, Federico; Parenti, P.; Tosello, Guido; Annoni,M.Publication date:2017Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Loaldi, D., Calaon, M., Quagliotti, D., Baruffi, F., Parenti, P., Tosello, G., & Annoni, M. (2017). Laser confocalmicroscope noise evaluation on injection compression moulded (ICM) transparent polymer Fresnel lenses.Poster session presented at 17th euspen International Conference & Exhibition, Hannover, Germany.D. Loaldi1,2, M. Calaon1, D. Quagliotti1, F. Baruffi1, P. Parenti2, G. Tosello1, M. Annoni2Laser confocal microscope noise evaluation on injection compression moulded (ICM) transparent polymer Fresnel lensesEuropean Society for Precision Engineeringand Nanotechnology (euspen), 17th International Conference,Hannover (Germany), 29th May – 2nd June 2017AbstractThe evaluation of an adequate and robust measuring strategy, forroughness assessment of polymer Fresnel lenses is put under assessment.An ‘on-sample’ measurement noise, is evaluated using a laser confocalmicroscope (OLYMPUS © Lext). Secondly, the lowest-noise roughnessmeasuring procedure, on an injection compression moulded (ICM) Fresnellens, is defined. A set of two different objectives is considered, i.e. astandard series (SO), against a long working distance one (LWD); twodifferent magnifications objectives, 50x and 100x and the use or not of adark environment.The noise evaluation is performed by comparing ‘on-sample’ noise with theone calculated on an optical flat. Noise is investigated by means ofestablished methods, i.e. subtraction and averaging methods. Afterwards,the lowest-noise analysis is structured following a 23 full factorialexperimental planning, whose factors are measuring working distance,objective magnification and room lighting. The result confirms a strongdifference of noise, using the considered objectives. The most interestingresult is that the performance of SO 50x objective is better than LWD 100x.Laser confocal microscope lowest noise optical set-up• Objective  Evaluate the best optical set-up to ensurelowest noise measuring routine for an injectioncompression moulded (ICM) transparent polymer Fresnellens• Increase quality of results [1] Absence of distortions• Increase measuring speed Find sufficient accuracy• Avoid small working distance possible collisions Assess long measuring vertical step• Laser confocal microscope• Suitable for industrial manufacturing application• Flexible working conditions• Coherent laser source of 510 nm• Noise evaluation [2]• Averaging method• Subtraction method• Compared measuring optical set-up on• Magnification• Working Distance• Environmental lighting conditions• Specimen employed for analysis (Figure 1)• ICM Fresnel lens in Cyclo-Olephin Polymer material•Central circle  1.496 µm• Slope on center  < 1°•Horizontal pitch 748.9 µm Experiments performed to achieve optimalinstrument set up using a metrological approachValidation of an “on-sample” noise evaluation procedureAcknowledgementsThis research work was undertaken in the context of MICROMAN project (“Process Fingerprint for Zero-defect Net-shape MICROMANufacturing”, http://www.microman.mek.dtu.dk/). MICROMAN is a MarieSkłodowska-Curie European Training Network supported by Horizon 2020, the EU Framework Programmefor Research and Innovation (Project ID: 674801). The Department of Mechanical Engineering at theTechnical University of Denmark and the Department of Mechanical Engineering at Politecnico di Milano(Italy) are thanked for supporting the collaboration between the two institutions in the project“Technological Signature in Precision Injection Compression Moulding of Polymer Fresnel Lenses”.ConclusionThis study shows the possibility to evaluate measurement noise directly ‘on-sample’ when the specimen surface roughness Sq, and the noise evaluation,have similar values. This is validated evaluating the same Sqnoise of 10 nm on-sample and on an optical flat. The lowest-noise measuring strategy is identifiedin the cases of maximum AN, in absence of measurement disturbances.Moreover noise estimation with 50x SO results lower than 100x LWD objectives,in the first case 10 nm against 15 nm.References[1] F. Gao and R. Leach, “Surface measurement errors using commercialscanning white light interferometers,” Meas. Sci. Technol., vol. 19, no. 1, p.15303, 2008.[2] C. L. Giusca, et al, Calibration of the scales of areal surface topography-measuring instruments: part 1. Measurement noise and residual flatness. Meas.Sci. Technol. 23 35008, 2012.Fig. 1: Measuring roughness in the central region of the Fresnel lens and 3D acquisition with a 5x magnification objectiveTable 1: 3-factor/2-level full factorial DOELowest noise measuring set-upFig. 2: DOE results of noise evaluation (Sqnoise) on Fresnel lens for the different experimental conditions Table 2: Noise evaluation in terms of Sqnoise compared on optical flat and Fresnel lens1 Department of Mechanical Engineering, Technical University of Denmark (DTU), Produktionstorvet, Building 427S, Kgs. Lyngby, DK-2800, Denmark2 Department of Mechanical Engineering, Politecnico di Milano, Campus Bovisa Sud, via La Masa 1, 20156 Milano, Italy10 mmExperimental conditions Objective propertiesObjective series ObjectiveMagnificationRoomIlluminationNumerical Aperture ANWorking DistanceWD / mmSO 50x ON 0.95 0.35 SO 50x DARK 0.95 0.35 SO 100x ON 0.95 0.35 SO 100x DARK 0.95 0.35 LWD 50x ON 0.5 10.60LWD 50x DARK 0.5 10.60 LWD 100x ON 0.8 3.40 LWD 100x DARK 0.8 3.40  012345678910Averaging SubtractionOptical Flat 9.7 9.7Fresnel Lens 8.1 9.6Max (Sqnoise)  /nmExperimental conditions for noise evaluation • Design of Experiments (DOE) technique applied• 3-factor/2-level full factorial design (Table 1)• resulting in a total of 8 different scan settings• Objective series Standard Objectives (SO),Long Working Distance (LWD)• Objective Magnification 50x, 100x• Room Illumination  ON, DARK• 10 repeated measurements for each set-up• Measuring conditions•  Image dimensions 258x258 µm2•  4096x4096 points per image010203040506070SO SO DARK LWD LWD DARKMax (Sqnoise)  /nm50x Subtraction method 50x Average method 100x Subtraction method 100x Average method

Laser confocal microscope noise evaluation on injection compression moulded (ICM) transparent polymer Fresnel lenses

http://orbit.dtu.dk/ws/files/133236128/Poster_euspen2017_LaserScanningConfocal_v3.pdf

Laser confocal microscope noise evaluation on injection compression moulded (ICM) transparent polymer Fresnel lenses

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology