Large Field of View Telecentric Lenses

Posted: July 2017 | See all Trending in Optics topics

Next Generation of Spherical Lenses

As optical applications continue to increase in complexity, their performance requirements are becoming more demanding and are often no longer met by the standard tolerances of spherical lenses.

Therefore, the next generation of spherical lenses must have tighter diameter, centration, and surface quality tolerances. These specifications facilitate “drop in” assemblies, which reduces the need for complicated assembly procedures such as active alignment, eases alignment, and reduces wavefront error. The looser specifications of previous spherical lens generations no longer hold the level of precision required to meet the increasing demands of future applications.

What’s Next?

Beyond these tightened tolerances, the future of standard lenses could be quite different from conventional spherical lenses as increasingly demanding applications continue to require even higher performing optics.

Metamaterials
Molded Surfaces
Polarization Directed
Variable Focus Moiré

Metamaterials

Metamaterials are engineered to have properties beyond those of conventional materials. A wide variety of properties can be manipulated and metamaterials could possibly even be used to create lenses that go beyond the diffraction limit.

Aspherized Molded Surfaces

Aspherized surfaces can be quickly and economically added to spherical lenses through a unique polymer molding process. This provides similar spherical aberration correction to machined aspheres at a fraction of the cost. We use this technique to create our Aspherized Achromatic Lenses.

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Polarization Directed Flat Lenses

Polarization Directed Flat Lenses function differently than typical spherical lenses. The focal length is defined by a holographically recorded wavefront profile, rather than by the curvature of the surfaces. They have less weight and volume than comparable spherical lenses, making them ideal for space-constrained applications. The Polarization Directed Flat Lenses are the result of exciting new design technology, allowing for endless possibilities across various industry fields and application types.

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Variable Focus Moiré Lenses

Variable Focus Moiré Lenses consist of specially structured cascaded Diffractive Optical Elements (DOEs). These lenses are continuously adjustable over a wide focal length range by simply rotating the elements. They exhibit aberration-free performance with monochromatic illumination and can be adapted for wavelengths from the UV to the IR.

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Edmund Optics Next Generation of Spherical Lenses

Recognizing the need for higher performing optics, Edmund Optics has tightened the standard tolerances of all TECHSPEC^® spherical lenses.

New tightened standard tolerances for ease of integration

All TECHSPEC^® spherical lenses now held to a diameter tolerance of +0.000/-0.025mm

All TECHSPEC^® spherical lenses now held to a scratch-dig value of 40-20

All TECHSPEC^® singlet lenses with a focal length >10mm now feature a centration of <1 arcminute

Facilitate "drop in" assemblies, reducing the need for complicated assembly procedures such as active alignment

Technical Diagram

Centration errors in a lens produce tilt and axial coma, which can be detrimental to wavefront error, resolution, and encircled energy. Lenses without our tightened centration tolerance will suffer in these areas. The 3D wavefront plot below shows the wavefront error from a 3 arcmin centration error in our 25mm diameter x 100mm focal length aspheric lens #89-442. This 3 arcmin centration error caused a PV wavefront error of 3λ/4 at 532nm, but tightening the centration tolerance to the new TECHSPEC^® centration tolerance of 1 arcmin reduces the PV wavefront error to λ/4 at 532nm.

Figure 1: Wavefront error due to centration errors

FAQ's

What is the benefit of the improved diameter tolerance?

Maintaining the diameter within 0.025mm ensures the lenses will seat and align accurately within a well-designed barrel, aligning the optical axis of the lens with the mechanical axis of the assembly. Diameter tolerance is a critical mechanical tolerance that must be considered when mounting an optic. Deviations from the nominal diameter may prevent lenses from seating properly in their mounting fixture, leading to decenter or tilt within the optical assembly.

Why is the tightened centration specification important?

This precision alignment of the optical axis ensures the lenses can be used in demanding imaging applications. When combined with the precision diameter tolerances, this reduced wedge specification leads to minimal image runout in an optical assembly.

How does the improved surface quality affect optical performance?

This precision cosmetic specification ensures the lenses can be used in demanding laser-based systems. Even minor scratches or pits on the optical surface can lead to scattered light, which can be detrimental in laser-enabled applications. Surface quality also impacts the laser damage threshold of a lens. Lenses with poor surface quality may fail when subject to moderate laser power or fluence. Scratches and digs in a lens could cause laser light to scatter back and forth, destroying the coating.

Training Materials

Tightened Tolerances for Spherical Lenses

Detailed description of the tightened tolerances made to all TECHSPEC^® spherical lenses.

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Understanding Optical Specifications

Explanation of common optical specifications required for determining performance and manufacturing requirements.

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