Prototype Optics in One Week

request a quote

OPTICS YOU NEED FAST AND ACCURATE.

Submit-RFQ

Art of Making Spheres

We’ll walk you through the process, and invite you to visit the Resource Library for technical resources at every step.

Prism Specification
Prism Manufacturing
Prism Testing
Prism Coatings
Prism Delivery
Prism Future

Spheres, the most common type of optic, have at least one surface that is a segment of a ball. A spherical lens is made with a particular radius of curvature. This radius can be as short as 1mm or very long, to where plano is an infinite radius. Spheres are found in camera lenses, machine vision systems, laser beam shaping, and similar applications.

Specifying Spheres

Specifying spheres begins with choosing an optical material. Next, the designer selects a diameter, thickness and surface radii. Finally, mechanical and optical attributes are toleranced in accordance with the designer’s performance requirements and the manufacturer’s capabilities

Reducing the range of a tolerance will add manufacturing cost. The task in selecting tolerances is to minimize cost while ensuring good optical performance. The Cost of Tolerancing gives valuable insight into optimally tolerancing optical components, written in collaboration between an optical engineer, an optics manufacturer, and a metrologist.

For more information on our sphere manufacturing please see:

Optimax Tools

Manufacturing Tolerance Chart
Test Plate Library
Preferred Glass List
Aerospace Glass List

Spherical Lens Manufacturing Technology

Optimax makes spheres from optical materials such as glass, fused silica, crystals and ceramics for UV, Visible and IR applications using proprietary “grind and shine” techniques to produce low scatter surfaces. Whether to prepare lens surfaces or to correct wedge, CNC machine tools are employed throughout the spherical fabrication process.

For more information please see:

Sphere Limits

General Comments on Manufacturing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • As requirements move closer to a min or max shown, the more challenging the part will be.
  • During manufacturing, the lens is over-sized in diameter.

Manufacturing Limits for Spherical Surfaces

Based on Form Error Tolerance

Attribute
Minimum
Maximum
Diameter (mm) 3 400
Radius (mm) ±1 2
Aspect Ratio (Diameter/Center Thickness) <1:1 30:1
Included Angle (°) 0 2103
1Limited by machine envelope
2Metrology dependent. Avoid 3-10 meter radii when possible, choosing to stay plano instead. It will be less expensive too.
3This represents highest values possible. Actual value possible depends on finished and metrology options available plus tolerance range available for a given part.

General Comments on Manufacturing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • As requirements move closer to a min or max shown the more challenging the part will be.
  • Certain combinations may not be possible – Choosing Max Sag and Min Diameter on concave surfaces for example.
  • Interferometric testing of aspheres is extremely case specific. The slower the onset of departure, the more likely interferometric testing is possible.
  • During manufacturing the lens is oversized in diameter. Be aware, forms well behaved within clear aperture may turn exotic or undefined just beyond final diameter.

Manufacturing Limits for Aspheric Surfaces

Based on Form Error Tolerance

Form Error > 2μm Lower Resolution Profilometry (2-D)1
Attribute
Minimum
Maximum
Diameter (mm) 3 250
Local Radius (mm) -8 (Concave)
Sag (mm) 0 502
Departure (mm) 0.01 20
Included Angle (°) 0 120
Form Error 0.5 – 2μm Higher Resolution Profilometry (2-D)1
Attribute
Minimum
Maximum
Diameter (mm)3 3 250
Local Radius (mm) -12 (Concave)
Sag (mm) 0 252
Departure (mm) 0.01 20
Included Angle (°) 0 150
Form Error < 0.5μm Interferometry with Stitching (3-D)
Attribute
Minimum
Maximum
Diameter (mm)3 3 250
Local Radius (mm) -13 (Concave)
Sag (mm) 0 252,4
Departure (mm) 0.002 1
Included Angle (°) 0 120+5
1Typical metrology is Zygo MetroPro plots for interferometry
2For concave surfaces the maximum may be smaller, limited by tool clearance first. Short radii have lower maximums
3Larger diameters can be accommodated using multiscan fusion
4Total sag allowed is a function of diameter, determined by fringe resolution of the interferometer
5Very basic forms (paraboloid, ellipsoid) can have higher included angles

Thin Film Coating Manufacturing Limits

Coating Capabilities
Attribute
Minimum
Maximum
Diameter 3mm 500mm
Wavelength 193nm 6000nm
Use Environment Vacuum >95% RH
Durability Moderate abrasion Severe abrasion
Measurement 68°, s, p, average polarization
Laser Damage Threshold 1064nm: >30J/cm2@10ns, >1MW/cm2CW
Layers 1 200
* Soft Tolerancing Units **Stitching/CGH dependent

General Comments on Manufacturing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • As requirements move closer to a min or max shown fabrication becomes more difficult.
  • Certain combinations are unattainable, e.g. 3mm convex radius with 100mm length.
  • Certain configurations add significant fixturing costs, e.g. crossed axis cylinders, cylinders/spheres.
  • Interferometric testing of cylinders is somewhat case specific. Aperture coverage is often limited by the range of diffractive nulls available.
  • Length is always the dimension along the plano axis and width is the dimension across the power axis.

Manufacturing Limits for Cylindrical Surfaces Based on Manufacturing Method

Rod or Arbor
Attribute
Minimum
Maximum
Length (mm) 3 5001
Width (mm) Radius dependent 2 < 2x Radius
Cylinder Radius (mm) – Convex Only 2 150
X-Y
Attribute Minimum Maximum
Length (mm) 3 300
Width (mm) 2 300
Cylinder Radius (mm) 10
Concave sag to flat (mm) 0.1002 =Radius
1This is at minimum radius and width. The part-specific minimum will grow in proportion to radius.
2Flat surfaces lead to scratching problems and polisher contact issues. For both practical and economic reasons consider plano here.

Manufacturing Limits for Freeform Surfaces

Attribute
 Tolerancing Limit*
Diameter (mm) +0, -0.010
Center Thickness (mm) ± 0.050
Irregularity – Interferometry
(HeNe fringes)
0.1**
 Irregularity – Profilometry (μm)  ±1.0
 Wedge Lens – ETD (mm)
 TBD
 Surface Roughness (Å RMS)  10
* Soft Tolerancing Units **Stitching/CGH dependent

General Comments on Manufacturing Limits

    • This represents a general list of soft limits and is intended for reference only.
    • As requirements move closer to a min or max shown, the more challenging the part will be.

Manufacturing Limits for
Prism Surfaces

Attribute
Minimum
Maximum
Diameter (mm) 3 300
Thickness 1 150
Aspect Ratio1 1 502
1Diameter divided by thickness
2This represents highest values obtained. When at maximum other minimums (irregularity) may not be possible. Will be smaller with less well behaved materials.

Sphere Tolerancing Limits

General Comments on Tolerancing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • Reducing tolerance range increases costs.
  • Optimax advises a close consideration of budget (tolerance, delivery or dollar) versus need be made prior to choosing any value below.
  • Robust sensitivity analyses will help yield the most cost effective tolerancing.

Tolerancing Limits for Spherical Surfaces

Attribute
Sphere Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Diameter (mm) +0, -0.010
Center Thickness (mm)4 ± 0.020 
Sag – Concave (mm)  ± 0.010 
Clear Aperture  100%5
Radius (mm)6 ± 0.0025 or 1 HeNe fringe7
Irregularity (HeNe fringes)8 0.059
Wedge Lens – ETD (mm)  0.00210
Bevels – Face Width @ 45° (mm)  ± 0.0511
Scratch – Dig (MIL-PRF-13830B)12 <10 – 5 
Surface Roughness (Å RMS)  313,14
4This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerances ranges.
5Of full aperture (FA)
6In addition to irregularity
7Whichever is correspondingly larger over the clear aperture
8Coverage dependent, stitched or otherwise, and also subject to system error
9As geometry requirements move closer to a min or max shown the less likely this is possible
10This specification is extremely tight and expensive. For a more economical limit, please consider using 0.005mm.
11Subject to measurement uncertainty
12Crystals and reflective materials will receive 40W inspection
13This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.
14With scan length and filter appropriate for the selected spatial period.

General Comments on Tolerancing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • Reducing tolerance range increases costs.
  • Robust sensitivity analyses will help yield the most cost-effective tolerancing.

Tolerancing Limits for Cylinder Surfaces

Attribute
Cylinder Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Length and width (mm) +0, -0.020
Center Thickness (mm)3 ± 0.020 
Sag – Concave (mm)  ± 0.020 
Clear Aperture  100%4
Radius5 ± 0.1% or 3 HeNe fringes6
Irregularity – Interferometry (HeNe fringes)7 0.18
Irregularity – Profilometry (μm)  ± 0.5 
Plano Axis Wedge – ETD (mm)  0.00512
Cylinder Axis Decentration – TIR (mm)9 0.01010
Axial Twist Angle (arcminutes)  3 
Bevels – Face Width @ 45° (mm)11 0/0mm max
Scratch – Dig (MIL-PRF-13830B)12 10 – 5 
Surface Roughness (Å RMS)13 5 
3This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerance ranges.
4Of full aperture (FA).
5In addition to irregularity.
6Whichever is correspondingly larger over the clear aperture.
7Typical metrology is Zygo MetroPro plots for interferometry.
8As geometry requirements move closer to a min or max shown the less likely this is possible.
9Optimax measures total indicated runout (TIR) as part is rotated. Actual decentration varies with focal length.
10This specification is extremely tight and expensive. For a more economical limit, please consider using 0.0100mm.
11Subject to measurement uncertainty.
12Crystals and reflective materials will receive 40W inspection.
13This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.

General Comments on Tolerancing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • Reducing tolerance range increases costs.
  • Robust sensitivity analyses will help yield the most cost-effective tolerancing.

Tolerancing Limits for Prism Surfaces

Attribute
Prism Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Diameter (mm) +0, -0.010
Center Thickness (mm)3 ± 0.010 
Sag – Concave (mm)  ± 0.010 
Clear Aperture  100%4
Power5 0.1 HeNe fringes6
Irregularity – Interferometry (HeNe fringes)7 0.18
Wedge Prism (window) – ETD (mm)9 0.00210
Bevels – Face Width @ 45° (mm)11 sharp 
Scratch – Dig (MIL-PRF-13830B)12 10 – 5 
Surface Roughness (Å RMS)13 4
3This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc.) will need larger tolerance ranges.
4Of full aperture (FA)
5In addition to irregularity
6This represents lowest values obtained. Will grow with diameter. Will be larger with less well-behaved materials.
7Typical metrology is Zygo MetroPro plot for interferometry.
8This represents lowest values obtained. Will grow with diameter. Will be larger with less well-behaved materials.
9Also known as parallelism or pyramidal error in prism manufacture.
10Tighter specification is possible but can be extremely expensive. For a more economical limit, please consider using 0.005mm.
11Subject to measurement uncertainty
12Crystals and reflective materials will receive 40W inspection
13This represents lowest values obtained. Actual values for crystalline materials, especially polycrystalline, will be higher.

General Comments on Tolerancing Limits

  • This represents a general list of soft limits and is intended for reference only.
  • Reducing tolerance range increases costs.
  • Optimax advises a close consideration of budget (tolerance, delivery or dollar) versus need be made prior to choosing any value below.
  • Robust sensitivity analyses will help yield the most cost-effective tolerancing.

Tolerancing Limits for Aspheric Surfaces

Attribute
Asphere Tolerancing Limit
Glass Quality (nd, vd) Melt Rebalanced and Controlled
Diameter (mm) +0, -0.010
Center Thickness (mm)6 ± 0.010 
Sag – Concave (mm)  ± 0.010 
Clear Aperture  100%7
Vertex Radius8 ± 0.1% or 3 HeNe fringes9
Irregularity – Interferometry (HeNe fringes)10 0.111
Irregularity – Profilometry (μm)10 ± 0.5 
Wedge Lens – ETD (mm)  0.00212
Bevels – Face Width @ 45° (mm)13 ± 0.05 
Scratch – Dig (MIL-PRF-13830B)14 10 – 5 
Surface Roughness (Å RMS)15 10 
6This is for the most well behaved materials. More difficult materials (CaF2, Ohara S-FPL, etc) will need larger tolerance ranges
7Of full aperture (FA)
8In addition to irregularity
9Whichever is correspondingly larger over the clear aperture
10A vertex radius tolerance is required in addition to irregularity
11As geometry requirements move closer to a min or max shown the less likely this is possible
12This specification is extremely tight and expensive. For a more economical limit, please consider using 0.005mm.
13Subject to measurement uncertainty
14Crystals and reflective materials will receive 40W inspection
15This represents lowest values obtained. Actual values for crystalline, especially polycrystalline materials, will be higher.

Here are manufacturing limits and tolerances specific to optical aspheres, prisms, cylinders and spheres. For more detailed information on any attribute, please contact sales@optimaxsi.com.

Testing Spheres

Optimax has one of the largest test plate libraries for making spheres. These test plates are certified to +/- 0.01% of radius. As required, Optimax can make test plates for special radii.

Future Capabilities

Optimax’s R&D department is continuously looking for ways to improve our fabrication process and produce higher quality optics. Our current research projects are designed to meet future market needs, such as:

  • New optical material processing
  • Higher laser damage threshold surfaces

For more information please see Optimax Innovation or contact sales@optimaxsi.com.

Technical Resources

Round-robin measurements of the toroidal window

Free-form surfaces are quickly becoming a desired and necessary shape for many refractive and reflective optical
systems. Some examples of free-form shapes are toroids, ogives, and other conformal windows. In this paper, we will discuss the round-robin study of surface irregularity measurements of a free-form toroidal window

Leveraging 3D Printing to Streamline Precision Optical Manufacturing

Optimax uses a variety of 3D printers to streamline our manufacturing processes. Download our technical paper today to learn about our results. 

Design and Manufacturing Considerations for Freeform Optical Surfaces

Freeform optical systems are becoming increasingly common due to new design and manufacturing methods. We present an example compact freeform optical system and describe considerations for transfer of the prescription of freeform surfaces for fabrication

The Manufacturing of a Multi-surface Monolithic Telescope with Freeform Surfaces

Monolithic multi-surface telescopes combined with freeform optical surfaces provide improvements in optical performance in a smaller footprint as compared to systems with spherical surfaces, while providing superior mechanical stability to traditional telescope assemblies. Three different monolithic telescope concepts, in different configurations and optical performance were produced as proof of concepts

Scaling-up freeform manufacturing: challenges and solutions

With optical technology and design advances, larger freeform optics are increasingly sought after by consumers for an expanding number of applications. This paper will present some of the challenges and solutions of extending freeform polishing capabilities from approximately 150 mm diameter parts to a component of over 500 mm in diameter

Robotic polishing in asphere manufacturing

Optimax improved the reliability of asphere polishing platforms at a demonstrated level. Download our technical paper today to learn about our results

Challenges in size scale up of freeform polishing processes

This paper will discuss challenges faced as a result of scaling up our freeform polishing process from parts with approximately 150 mm diameters, to polishing components with diameters over 600 mm

Temperature Variation of Pitch in a Pitch Pot

Opticians have for years kept polishing pitch in electrified containers called “pitch pots” that keeps it in at an elevated temperature. By insulating the top of a pitch pot, it will impact the temperature, which we will explore in this paper

U.S. National Committee proposed revision to the ISO Laser Damage Standard

The Optics and Electro-Optics Standards Council (OEOSC) Task Force (TF) 7 has proposed a Type 1 laser damage test procedure and deemed it the most valuable in the U.S. laser market. 

The Segmented Aperture Interferometric Nulling Testbed

This work presents an overview of the Segmented Aperture Interferometric Nulling Testbed (SAINT), a project that will pair an actively-controlled macro-scale segmented mirror with the Visible Nulling Coronagraph (VNC). 

Design Guidelines for Predicting Stress in Cemented Doublets

This explores quick predictive methods for calculating potentially risky stresses in cemented doublets underdoing temperature change that agrees well with finite element analysis. It also provides guidelines for avoiding stress concentrations

Statistical distributions from Lens Manufacturing Data

Optical designers assume a mathematically derived statistical distribution of the relevant design
parameters. Presented are measured distributions using
lens manufacturing data to better inform the decision-making process.

Techniques for Analyzing Lens Manufacturing Data

Optical designers assume a mathematically derived statistical distribution of the relevant design parameters. However, there may be significant differences between the assumed distributions and the likely outcomes from manufacturing. 

Rapid Optical Manufacturing of Hard Ceramic Windows and Domes

Hard ceramic conformal windows and domes provide challenges to the optical fabricator, due to the material hardness, polycrystalline nature, and non-traditional shape. Creative optical fabrication techniques, including VIBE™, help produce these types of optics cost-effectively

Cost Effective Fabrication Method for Large Sapphire Sensor Windows

Sapphire poses very difficult challenges to optical manufacturers due to its high hardness and anisotropic properties. These challenges can result in long lead times and high prices. Optimax is developing a high speed, cost effective process to produce such windows. 

Thermal instability of BK7 and how it affects the manufacturing of large high precision surfaces

When manufacturing precision optical surfaces of relatively larger sizes it is critical to understand the thermal stability of the substrate material. The material properties associated with thermal homogenization are commonly reviewed and soak schedules are created. 

Reduced cost and Improved Figure of Sapphire Optical Components

Optimax has developed a fabrication process that not only reduces cost but also aids in producing spherical sapphire components to better figure quality. 

Current use and potential of additive manufacturing

Additive manufacturing, or 3D printing, has become widely used in recent years for the creation of both prototype and end-use parts. The flexibility is unparalleled and has opened the design space to enable features like undercuts and internal channels. 

Incorporating VIBE into precision optics manufacturing process

The VIBE™ process is a full-aperture, conformal polishing process that has the potential to be introduced in areas of today’s modern optics manufacturing process

Evolving rocket optics applications drive manufacturing advances

Improvements to sensing hardware and image processing for airborne optical systems have inspired designers to propose new optics and windows to be: more precise, conformal/freeform and multi-functional. 

Early Considerations to Aid Later Manufacturing

With so many types of optical components, there are many considerations early in the manufacturing process that can save resources

Magnetorheological Fluid Template Mechanical Chemical Effects

Optimax developed a new magnetorheological (MR) fluid for studying the relative contributions of mechanics and chemistry in polishing hard materials. 

Profit through predictability: The MRF difference at Optimax

In an effort to reduce variation and improve predictability, Optimax integrated magnetorheological finishing into its aspheric lens manufacturing process. 

Optical Systems: Transmissive high-energy laser optics

There are many decisions to make when designing, specifying, manufacturing, and testing optical components for high-energy laser systems — each is a potential failure mechanism that must be understood and controlled

Freeform optical manufacturing and testing processes for IR conformal window and dome

Complete freeform optical fabrication process that includes ultrasonic generation of hard ceramic surfaces, high speed VIBE polishing, sub-aperture figure correction of polycrystalline materials, finishing and final testing of freeform surfaces

Assembly Method Considerations for Cemented Assemblies

When cementing lenses together at Optimax, there are main options for assembly methods. Each method has its own benefits and challenges to be considered. 

Specification and Control of Mid-Spatial Frequency Wavefront Errors in Optical Systems

This paper is an introduction to the specification and tolerancing of Mid-spatial frequency (MSF) ripple or waviness

Surface Irregularity

This paper will define surface irregularity for spherical surfaces, offer information on measurement methods for testing surface irregularities, and some specification guidelines

Radius Tolerancing

There are two main paths for tolerancing spherical radii: power tolerance and linear radius tolerance. Both measure change relative to a nominal value, but the metrology used is the key difference. 

The Cost of Tolerancing

The cost of lenses is strongly dependent on the difference between the specified tolerances and the limits of the optics manufacturer, the coater, and the metrologist. 

Manufacturability study of CLEARCERAM® (T008) compared to other low CTE materials

CLEARCERAM® was developed in an attempt to reduce the thermal expansion and approach a true zero expansion material. This improves grinding and polishing rates by 39%

Better Polishing through Chemistry

Learning the chemical aspects of optical polishing can lead to better optics in less time.

Transmitted Wavefront Error Correction

Tolerancing optical lenses in transmission rather than reflection offers financial, performance and delivery advantages to a given class of aspheric optics. 

Vibe: A New Process for High Speed Polishing of Optical Elements

The concept for polishing optical elements with a process called VIBE is presented, application to non uniformly sloped optics such as aspheric shapes is detailed, and initial results on spherical surfaces are presented

Round Robin Testing of the Optimax Optidome

OptiDomes act as a standard for metrology testing of various testing methods for measuring the surface quality, mechanical attributes and/or the transmitted wave-front error of hemispherical/spherical domes.

Advances in ALON™ Optical Component Fabrication

Aluminum oxynitride (ALON™) spans from the UV to the IR and has excellent ballistic characteristics and is used to improve quality in manufacturing. 

Increased UV transmission by improving the manufacturing process for FS

With increasing demand for deep UV applications, special considerations must be taken to produce the optics. Specifically, as the wavelength of incident light decreases, the importance of smooth surfaces increases. 

Varying electro-kinetic interactions to achieve… on ZnS

A conventional study was conducted with infrared material zinc sulfide with the goal of producing defect-free polished surfaces in a predictable amount of time. 

VIBE™ finishing to remove mid-spatial frequency ripple

The VIBE™ process is a full aperture, conformal polishing process incorporating high frequency and random motion designed to rapidly remove sub-surface damage in a VIBE pre-polish step and eliminate mid-spatial frequency (MSF) errors in a VIBE finishing step.

R&D and the Optics Manufacturing Shop Floor

Historically, the R&D department and the optical manufacturing shop floor have been independent entities. Optimax has been able to integrate the two departments for faster deployment and practical utilization. 

VIBE™ Rapid Polishing Process to Smooth Optical Surfaces

The VIBE process is a full-aperture, conformal polishing process that uses high-frequency and random motion to rapidly remove sub-surface damage and eliminate mid-spatial-frequency surface errors.

Optimax Brochures

Expedited Optics Manufacturing & Delivery

With years of experience perfecting its Lean manufacturing processes, Optimax is uniquely qualified to offer fast, on-time deliveries.

Optimax is the world’s leading rapid delivery manufacturer of custom optical components. Since its founding, Optimax has recognized that industries and institutions need fast deliveries of high quality, precision optics and has invested more than 15 years perfecting highly reliable and effective Lean processes. To learn more about these and other Optimax innovations, please visit About Optimax.

Customers trust Optimax to reliably manufacture their most complex optics on time. In the unlikely event that an expedited delivery is late, Optimax policy is to refund any unearned premium.

When you need optics fast and right!

Optimax excels at grinding, polishing and coating precision optics quickly and reliably. We can deliver high precision optics in as little as one week.

Optimax Capabilities

X