Microprismatic Fresnel Lens for Formation of Uniform Light Circle

At a Glance

Metadata	Details
Publication Date	2021-04-12
Journal	IEEE photonics journal
Authors	Minglei Fu, E. E. Antonov, Dmytro Manko, В. В. Петров, Kezhen Rong
Institutions	National Academy of Sciences of Ukraine, Institute for Information Recording
Citations	8
Analysis	Full AI Review Included

Microprismatic Fresnel Lens Fabrication: Diamond Material Solutions

This technical documentation analyzes the fabrication requirements for high-performance microprismatic Fresnel lenses, as detailed in the referenced research, and outlines how 6CCVD’s specialized MPCVD diamond materials provide a superior platform for replicating and advancing this technology.

Executive Summary

The research demonstrates a novel microprismatic Fresnel lens design capable of transforming a parallel light beam into a uniformly illuminated light circle, a critical component for advanced optical sensor systems and four-quadrant photodetectors.

Core Achievement: Successful fabrication and experimental verification of a transforming Fresnel lens that generates a uniform 9.0 mm light circle at a 20 mm focal distance.
Fabrication Method: The study emphasizes the use of the diamond cutting method to achieve “exceedingly high optical quality” and mirror-like surfaces, circumventing the inherent defects of traditional photolithography.
Material Limitation: The lens was fabricated from Polycarbonate (PC), resulting in a transmission limited to approximately 70% due to scattering losses and material defects.
6CCVD Value Proposition: 6CCVD Single Crystal Diamond (SCD) offers a path to eliminate these limitations, providing near-perfect transmission (T > 99%) across the visible spectrum and superior surface quality (Ra < 1 nm), maximizing efficiency and enabling high-power operation.
Engineering Advantage: Diamond (SCD) is the optimal material for ultra-precision diamond cutting, ensuring the highest fidelity replication of the complex microrelief structure (250 µm to 490 µm relief depth) required for this application.

Technical Specifications

The following hard data points were extracted from the simulation and experimental results of the microprismatic Fresnel lens:

Parameter	Value	Unit	Context
Target Wavelength (λ)	0.532	µm	Green laser spectrum used for testing
Lens Material Refractive Index (n₁)	1.585	N/A	Refractive index of Polycarbonate (PC) at 0.532 µm
Nominal Focal Distance (f)	20	mm	Distance for uniform light circle formation
Working Lens Diameter (D_L)	45	mm	Manufactured diameter (f/D_L ratio ~0.44)
Plate Thickness (δ)	6.0	mm	Thickness of the PC forming plate
Target Light Circle Diameter (d₁)	9.0	mm	Diameter of the uniformly illuminated circle
Central Blank Zone Radius (r₀)	1.5	mm	Designed to eliminate central intensity maximum
Required Relief Depth Range (h)	250 to 490	µm	Depth variation across the structural zones
Experimental Transmission	~70	%	Limited by scattering losses in PC
Surface Quality Requirement	Exceedingly High	N/A	Achieved via diamond cutting (mirror-like quality)

Key Methodologies

The fabrication and testing of the microprismatic Fresnel lens relied on precision design and manufacturing techniques:

Simulation and Geometric Calculation: Developed a simulation method for microrelief structures with flat conical working facets, calculating geometric parameters (radii R_k and inclination angles α_k) necessary to form a uniform light circle.
Microrelief Structure Design: The lens was designed with seven structural zones, each composed of three to five constituent microprismatic elements. The required relief depth varied from 250 µm to 490 µm.
Diamond Cutting Fabrication: Samples were fabricated using the diamond cutting method on a flat Polycarbonate (PC) sheet (6.0 mm thickness). This technique was specifically chosen to minimize surface defects and achieve the necessary high optical quality, which is superior to photolithographic methods.
Optical Investigation: The manufactured lenses were experimentally investigated using a uniformly collimated green laser beam (λ = 0.532 µm).
Performance Measurement: A moveable photodetector with a 0.4 mm slit diaphragm was used to register the light-intensity profiles and confirm the formation of the predicted uniformly illuminated circle.

6CCVD Solutions & Capabilities

The research highlights the critical need for ultra-high surface quality and precise microrelief structures, achievable only through diamond cutting. 6CCVD’s MPCVD diamond materials are the ideal platform to overcome the transmission and stability limitations encountered with Polycarbonate (PC).

Applicable Materials

Material Recommendation	Grade	Application Justification
Single Crystal Diamond (SCD)	Optical Grade	Primary Recommendation. SCD offers the highest purity, lowest absorption, and superior thermal management. It eliminates the 30% scattering losses observed in PC, providing T > 99% transmission at 0.532 µm and across the UV/IR spectrum. Ideal for high-power laser applications or environments requiring maximum optical efficiency.
Polycrystalline Diamond (PCD)	Optical/Thermal Grade	Suitable for applications requiring larger diameters (up to 125 mm) or thicker substrates (up to 10 mm). While slightly higher scattering than SCD, PCD still vastly outperforms PC in hardness, thermal conductivity, and chemical inertness.

Customization Potential

6CCVD specializes in providing materials tailored precisely to the demands of ultra-precision optics and diamond cutting applications:

Custom Dimensions: The paper used a 45 mm diameter lens. 6CCVD routinely supplies SCD and PCD plates/wafers up to 125 mm in diameter. We can provide custom thicknesses ranging from 0.1 µm (for thin film applications) up to 500 µm (SCD/PCD) or 10 mm (Substrates), easily accommodating the 6.0 mm thickness used in the study.
Ultra-Low Roughness Polishing: Since the research relies on the mirror-like quality of the working surfaces, 6CCVD guarantees Ra < 1 nm polishing for SCD and Ra < 5 nm for inch-size PCD, ensuring the highest possible fidelity for the microprismatic facets (250 µm to 490 µm relief depth).
Metalization Services: While not required for this specific refractive lens, 6CCVD offers in-house custom metalization (Au, Pt, Pd, Ti, W, Cu) for integration into complex optoelectronic systems or mounting structures.

Engineering Support

The successful replication and extension of this research—especially for high-power or non-visible spectrum applications—requires expert material selection.

Material Selection for High-Flux Optics: 6CCVD’s in-house PhD team can assist engineers in selecting the optimal diamond grade (SCD vs. PCD) and orientation to minimize absorption and maximize thermal dissipation for similar Light Beam Transformation or Optical Sensor System projects.
Global Supply Chain: We offer reliable global shipping (DDU default, DDP available) to ensure timely delivery of custom diamond wafers for research and production worldwide.

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

View Original Abstract

Focusing Fresnel lenses are used in many fields of applied optics. These devices are used in optical sensor systems for imaging and optoelectronic integration. The traditional Fresnel lens concentrates the light intensity on the center of the formed image. We present a microprismatic Fresnel lens that transforms a circular incident parallel light beam into a homogeneous light circle with the necessary diameter at a certain distance from the lens. These transforming Fresnel concentrators can be successfully used, for example, in monitoring devices to automatically adjust the output signal from four-quadrant photodetectors. Traditional focusing Fresnel structures are manufactured by photolithographic methods or adjustable direct laser recording with photoresists. These methods enable the formation of stepped optical structures, which have inherent surface defects, resulting in the formation of images that are not high in quality. The proposed specialized Fresnel concentrators can be easily fabricated via the diamond cutting method, which enables the manufacturing of flat working surfaces with exceedingly high optical quality. We also develop a method for simulating the Fresnel transforming lenses with flat conical working facets and calculate the geometric parameters of the circular concentrators. We then apply the simulation results to the diamond cutting method and fabricate the microprismatic light transforming lens samples. These samples are then investigated experimentally with a collimated laser beam. The obtained data agree with the theoretical predictions.