Development of a Web-Based e-Portal for Freeform Surfaced Lens Design and Manufacturing and Its Implementation Perspectives

At a Glance

Metadata	Details
Publication Date	2025-01-16
Journal	Machines
Authors	Shangkuan Liu, Kai Cheng, N. Dianat
Institutions	Brunel University of London
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: Freeform Surfaced Optics Manufacturing

This document analyzes the requirements for ultraprecision machining of freeform surfaced optics, as detailed in the research paper, and aligns them with the advanced MPCVD diamond solutions offered by 6ccvd.com.

Executive Summary

The research validates an integrated digital workflow for personalized freeform varifocal lens design and manufacturing, relying heavily on high-precision Single-Point Diamond Turning (SPDT).

Core Application: Personalized freeform surfaced varifocal lenses, requiring nano-level accuracy and stringent surface quality (Ra).
Manufacturing Method: Ultraprecision machining utilizing Fast Tool Servo (FTS) SPDT.
Critical Tooling Requirement: Polycrystalline Diamond (PCD) tools are explicitly required due to the abrasive nature of the workpiece materials (e.g., polycarbonate).
Digital Integration: The system uses an e-portal combining R-Script modeling (Winthrop method) and COMSOL Multiphysics for ray tracing simulation and optical performance validation.
Material Specification: The case study utilized polycarbonate (n = 1.5848) and required precise control over geometric parameters (e.g., 0.35 mm tool radius, 60° included angle).
Performance Validation: Ray tracing simulations confirmed significant optical performance improvement, reducing the RMS ray radius from 1.82 x 10⁴ to 5.79 x 10³.
6CCVD Value Proposition: We supply high-grade MPCVD PCD material, essential for manufacturing the superior diamond tools required for deterministic ultraprecision machining of these complex freeform surfaces.

Technical Specifications

The following hard data points were extracted from the experimental setup and simulation parameters:

Parameter	Value	Unit	Context
Lens Material (Case Study)	Polycarbonate (C₁₆H₁₄O₃)_n	N/A	Progressive Addition Lens (PAL)
Refractive Index (n)	1.5848	N/A	Material constant for simulation
Abbe Number (V_d)	27.86	N/A	Material constant for simulation
Diopter (D)	4	N/A	Refractive power of the optics
Calculated Center Thickness (CT)	1.1265	mm	Based on D, n, and h
Estimated Edge Thickness (ET)	1.5	mm	Simulation input
Lens Blank Radius (h)	30	cm	Simulation input
Standard Wavelength (λ)	550	nm	Standard visible light assessment
PCD Tool Cutting Edge Radius	0.35	mm	Experimental SPDT setup
PCD Tool Included Angle	60	°	Experimental SPDT setup
Computational Domain (Ω)	[-30, 30]²	mm	Standard varifocal lens size
RMS Ray Radius Reduction	1.82 x 10⁴ to 5.79 x 10³	N/A	Optical performance improvement post-optimization

Key Methodologies

The integrated manufacturing and validation process relies on a seamless digital-to-physical workflow, with ultraprecision machining being the final deterministic step.

Prescription Data Import: Customer prescriptions (SPH, CYL, AXIS, ADD) and geometric parameters (Corridor Length, Far-Zone Distance) are input via the e-portal.
Material Selection: Optical material properties (Refractive Index, Abbe Number, Density) are selected (e.g., Polycarbonate, n=1.5848).
Computational Modeling: The freeform surface (Progressive Addition Lens, PAL) is defined using mathematical equations (e.g., Winthrop’s eighth-order polynomial power law) written in R-Script.
Surface Generation & Visualization: The platform generates a surface data point cloud file, 2D contour plots, and 3D surface topography models.
Ray Tracing Simulation: The point cloud data is imported into COMSOL Multiphysics 6.0 to construct a 3D optics model and simulate optical performance (focal points, aberrations, light distribution) based on ISO 8980-1 standards.
Toolpath Generation: The validated surface geometry is converted into toolpath instructions for the ultraprecision machine (UPL250).
Ultraprecision Machining: SPDT using high-performance Polycrystalline Diamond (PCD) tools (0.35 mm radius, 60° angle) is executed to achieve the required nano-level surface accuracy.

6CCVD Solutions & Capabilities

The successful replication and advancement of this freeform optics manufacturing process depend critically on the quality and performance of the diamond tooling used in SPDT. 6CCVD provides the highest quality MPCVD diamond materials necessary to meet these stringent requirements.

Applicable Materials

The research explicitly requires superior performance PCD tools for machining abrasive polymers. 6CCVD is the ideal partner for supplying the raw material for these tools.

Material	Application in Research Context	6CCVD Capability
Polycrystalline Diamond (PCD)	Required for SPDT Tooling. Provides superior wear resistance and edge retention necessary for machining abrasive materials like polycarbonate and reinforced plastics used in ophthalmic optics.	We supply high-purity, high-density MPCVD PCD plates/wafers up to 125mm for tool fabrication, ensuring maximum tool life and deterministic surface quality.
Single Crystal Diamond (SCD)	Alternative for Ultra-High Precision. While PCD was used for the tool, SCD is the benchmark material for achieving the lowest possible surface roughness (Ra) in SPDT, suitable for machining non-ferrous metals or specialized optical components.	We offer optical-grade SCD plates up to 500µm thick, polished to Ra < 1nm, ideal for next-generation optical molds or direct diamond optics.

Customization Potential

The precision required for freeform optics necessitates highly customized material dimensions and finishing. 6CCVD’s capabilities directly address the needs of tool manufacturers and advanced optics researchers:

Custom Tool Blanks: We provide PCD and SCD material in custom dimensions and thicknesses (0.1µm to 500µm) to match the specific geometry required for FTS/SPDT tool fabrication (e.g., the 0.35 mm radius tool used in the experiment).
Surface Finishing: Achieving the required nano-level accuracy in the final lens surface starts with the tool quality. We guarantee ultra-low roughness polishing:
- SCD: Ra < 1nm
- Inch-size PCD: Ra < 5nm
Metalization Services: For tool mounting, heat dissipation, or integration into FTS systems, 6CCVD offers in-house custom metalization layers (Au, Pt, Pd, Ti, W, Cu) tailored to the client’s bonding requirements.

Engineering Support

The integration of complex modeling (Winthrop method, COMSOL) with deterministic manufacturing (SPDT) requires deep material science expertise.

6CCVD’s in-house PhD team specializes in the mechanical and thermal properties of MPCVD diamond. We can assist tool fabricators and research teams with:

Material Selection Optimization: Advising on the optimal PCD grade (grain size, density) to maximize tool life and minimize chipping when machining specific abrasive polymers or composites used in freeform optics.
Tool Geometry Consultation: Providing material specifications that support the fabrication of complex tool geometries, such as the 60° included angle and 0.35 mm radius used in this freeform lens project.
Global Supply Chain: Offering reliable, global shipping (DDU default, DDP available) to ensure timely delivery of critical diamond materials for continuous manufacturing operations.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

In modern freeform surfaced optics manufacturing, ultraprecision machining through single-point diamond turning (SPDT) plays a crucial role due to its ability to meet the high accuracy demands of optical design and stringent surface quality requirements of the final optic. The process involves meticulous steps, including optic surface modeling and analysis, optic design, machining toolpath generation, and manufacturing. This paper presents an integrated approach to customized precision design and the manufacturing of freeform surfaced varifocal lenses through a web-based e-portal. The approach implements an e-portal-driven manufacturing system that seamlessly integrates lens design, modeling and analysis, toolpath generation for ultraprecision machining, mass personalized customization, and service delivery. The e-portal is specifically designed to meet the stringent demands of personalized mass customization, and to offer a highly interactive and transparent experience for the lens users. By using Shiny and R-script programming for platform development and combining COMSOL Multiphysics for the ray tracing simulation, the e-portal leverages open-source technologies to provide manufacturing service agility, responsiveness, and accessibility. Furthermore, the integration of R-script and Shiny programming allows for advanced interactive information processing, which also enables the e-portal-driven manufacturing system to be well suited for personalized complex products such as freeform surfaced lenses.

Tech Support

Original Source

DOI: https://doi.org/10.3390/machines13010059

References

2008 - Progress in the spectacle correction of presbyopia. Part 2: Modern progressive lens technologies [Crossref]
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1998 - A variational approach to progressive lens design [Crossref]
2014 - A variational-difference numerical method for designing progressive-addition lenses [Crossref]
1998 - Using Wavefront Tracing for the Visualization and Optimization of Progressive Lenses [Crossref]