High-Precision Aspheric Lenses - Enhanced Optical Systems

Avantier is a prominent producer of high-precision custom and standard aspheric lenses, designed to provide diffraction-limited performance for the most challenging optical systems globally. From quick prototyping to large-scale manufacturing, Avantier offers the knowledge necessary to decrease spherical aberration and lower system weight.

Strategic Applications

Aspheric lenses are incorporated into cutting-edge technologies utilized in essential sectors:

• Medical and Life Sciences: Endoscopes, high-resolution DNA sequencing, and laser surgery tools
• Aerospace and Defense: SWIR/LWIR thermal imaging and satellite reconnaissance
• Automotive and LiDAR: Autonomous vehicle sensors and heads-up displays (HUD)
• Industrial Metrology: 3D scanning and semiconductor inspection.

Why Choose Aspheric Lenses?

Conventional spherical lenses frequently exhibit deviation of marginal rays, resulting in unclear images. Aspheric lenses possess a detailed, non-spherical surface shape that:

• Removes spherical aberration: Guides all incoming light toward one precise focal point
• Lowers part count: One aspheric lens can frequently substitute for various spherical components, leading to lighter and more compact setups
• Improves edge clarity: Delivers exceptional image clarity throughout the complete field of view, even when using elevated numerical apertures (NA).

Manufacturing Capabilities (5–200 mm)

Avantier employs cutting-edge optical manufacturing techniques to achieve tolerances down to the sub-micron level. The in-house creation process guarantees that each lens conforms precisely to the specified prescription.

Source: Avantier Inc.

Custom Engineering and Prototyping

Avantier is not limited to production; rather, it collaborates closely with the user's engineering department. The company offers extensive assistance throughout the process, from Zemax design enhancement to assembly completion.

Material Selection and Processes

Avantier collaborates with an extensive range of materials to meet the particular wavelength needs:

• Precision Glass Molding: Ideal for producing low-temperature glass in a high-volume and cost-efficient manner
• CNC Grinding and Polishing: Most suitable for medium production quantities and large (up to 200 mm) diameter glass aspheres
• Diamond Turning (SPDT): Specialized for Infrared materials (Ge, Si, ZnSe) and plastics
• Magneto-Rheological Finishing (MRF): Used to attain exceptional accuracy in surface quality and figure refinement

Stock Aspheric Lenses: Ready for Immediate Integration

For quick development and research purposes, Avantier keeps a comprehensive supply of stock aspheres.

• Laser-Grade Aspheres: Optimized for high-power beam shaping and focusing
• Infrared (IR) Aspheres: Germanium and silicon substrates for thermal sensing

Uncoated and Coated Options: Available with AR, V-Coat, or Broadband coatings

Stock Aspheric Lenses

Avantier maintains an extensive inventory of stock aspheric lenses available for quick delivery. These lenses encompass a wide range of focal lengths, diameters, and materials, consisting of both laser-grade and uncoated optics.

Real-World Applications and Case Studies

Avantier's engineering team addresses intricate optical issues. Investigate the latest efforts in the integration of high-precision aspheric designs:

• Infrared Lens Design for Scientific Research: With a focus on design for manufacturing (DFM), Avantier created advanced IR aspheres that ensure consistency in temperature control and accuracy in delicate laboratory settings.
• Cold Atom Trapping and Imaging: Avantier developed a specialized lens system for trapping and visualizing individual atoms, which demands a very high numerical aperture (NA) along with performance that is limited by diffraction.
• Reverse Engineering of Complex Objectives: Utilizing Avantier’s suite of measurement tools, the team effectively analyzed and refined current objective and projection lens designs to increase production efficiency and minimize optical distortions.

Technical Resource: Performance Comparison

In the process of creating a system, selecting the appropriate lens shape is essential for the performance of the MTF (Modulation Transfer Function).

Spherical Versus Aspheric Spot Size (25 mm f/1 Lens)

Source: Avantier Inc.

Optical Advantages of Aspheric Lenses

Spherical Aberration Correction: Aspheric lenses are designed with precision to manage all incoming light rays towards one specific focal point, thereby removing spherical aberration. This results in improved image clarity, reduced blurriness, and guaranteed focus throughout the entire field. They are, therefore, ideal for imaging systems requiring high accuracy, laser collimation, and optical devices.

Figure 1. Aspherical lens (left) versus spherical lens (right). Image Credit: Avantier Inc.

Aspheric Versus High-Index and Pancake Lenses: High-index lenses leverage the properties of their materials to enhance light bending, whereas aspheric lenses refine their surface geometry to more effectively correct aberrations. In comparison to slim pancake lenses, aspheric lenses provide markedly improved image sharpness from one edge to the other and minimize distortion.

Advanced Surface Geometry and Freeform Capabilities: Avantier accommodates both rotationally symmetrical and freeform aspheric configurations. These designs exhibit curvature that varies with distance from the optical axis, providing greater adaptability in addressing intricate aberrations. Important metrics for surface profile include:

• Qbfs: RMS slope departure from a best-fit sphere
• Qcon: Sag departure from a base conic

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Structure of an Aspheric Lens

Aspheric lenses are optical components characterized by radially varying curvature, enabling them to correct aberrations more efficiently than spherical lenses. In contrast to conventional lenses that possess a consistent curvature, aspheric surfaces are specifically engineered to focus light with greater sharpness and precision.

These lenses are widely used in:

• High-resolution cameras
• Laser systems
• Automotive sensors
• LED optics
• Medical imaging

The surface of a rotationally symmetric asphere is expressed through a sag equation in mathematical terms:

Where:

• Z: sag of surface parallel to the optical axis
• s: radial distance from the optical axis
• C: curvature, inverse of radius
• k: conic constant
• A4, A6, …: 4^th, 6^th, … order aspheric coefficients

When every coefficient is nil, the resulting shape is a typical conic form, either elliptical, parabolic, or hyperbolic, varying with the value of k.

Image Credit: Avantier Inc.

Spherical Versus Aspheric Performance Comparison

As illustrated in the chart below, a 25 mm f/1 spherical lens generates considerably larger spot sizes when compared to a corresponding aspheric lens.

Source: Avantier Inc.

Aspherical lens family. Image Credit: Avantier Inc.

MTF Comparison: All Spherical Versus Aspheric Triplet Design

This table presents a comparison of the modulation transfer function (MTF) effectiveness between two triplet lenses: one composed solely of spherical surfaces and the other featuring a single aspheric surface.

Source: Avantier Inc.

Image Credit: Avantier Inc.

Avantier assesses and manages every essential element of surface precision:

• Form Error: Large-scale deviations, RMS or peak-to-valley
• Waviness: Mid-frequency undulations (slope error)
• Surface Roughness: High-frequency texture, relevant for scatter and laser performance
• Radius Error: Curvature deviation corrected by focus tuning

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Manufacturing Methods at Avantier

Source: Avantier Inc.

Figure 3. Precision glass molding platform. Image Credit: Avantier Inc.

Figure 4. Computer-controlled precision polishing. Image Credit: Avantier Inc.

Figure 5. Magneto-rheological finishing (MRF). Image Credit: Avantier Inc.

Figure 6. Polymer molding. Image Credit: Avantier Inc.

How to Select the Right Aspheric Lens for an Application

Key Considerations

• Mechanical integration (CAD, full prescription)
• Budget and production scale
• UV, VIS, IR compatibility
• Coating options (AR, IR, broadband)

Application-Based Lens Guide

Source: Avantier Inc.