Optimax logo Optical prisms can be found in dual channel instruments, anamorphic systems, imaging systems or any other application where beam steering and/ or image manipulation is needed. PRISMS Optimax logo Prisms have a unique language and characteristics in manufacturing. PRISMS Right Angle
Dispersion
Dove
Beam Folding
Precision Flats
Wedge
Windows
Brewster
Blocks
Mirror Substrates
Grating Substrates
Rhomboids
Optimax logo Optimax has phase shifting interferometers for precision measurement of flatness plus autocollimators and a Wild Goniometer for precision measurement of angles. PRISMS
OPTICS YOU NEED FAST AND ACCURATE.

Prism

Capabilities

Optimax prism-related capabilities are listed below. Due to having more than three sides polished or complex coatings, these components require longer deliveries.

The Art of Making Prisms

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
Manufacturing testing
Prism Coatings
Prism Delivery
Prism Future

Optimax prism manufacturing capabilities available with one week delivery include:

  • Right Angle
  • Dispersion
  • Dove
  • Mirror Substrates
  • Beam Folding
  • Precision Flats
  • Wedge
  • Grating Substrates
  • Windows
  • Brewster
  • Blocks
  • Rhomboids

Optical prisms are components with at least two polished plano surfaces separated by a wedge angle. These elements are used to reflect or refract light. Optical prisms can be found in dual channel instruments, anamorphic systems, imaging systems or any other application where beam steering and/or image manipulation is needed.

  • Integrating Bars
  • Compound Angles
  • Cubes
  • Alignment Aides
  • Beam Splitters
  • Polygons
  • Light Pipes

Optimax Tools

Cost tolerancing tool button
Manufacturing Tolerance Chart
Test Plate Library
Preferred Glass List
Aerospace Glass List

Specifying Prisms

Below are basic guidelines for defining part geometry:

  • Choose directly measurable physical perimeters. Use linear dimensions to theoretical sharps.
  • Specify directly measurable glass angles, not air angles.
  • Provide a light path to aid visualization. Indicate entrance, reflecting and exit surfaces.

The angle is the inclination of the two surfaces and the thickness is a separation at some point. The separation only needs to be positionally defined at one location on the optic. Specifying the thickest edge provides the easiest access for measurement and is preferred by Optimax. The specification can be the thinnest edge or centerline thickness if desired.

The geometry of three-sided prisms is defined by two angles and an altitude. The third angle and sides then become references. Outer shapes (perimeters) are typically rectangular, round or elliptical but can be anything within Optimax’s shaping capabilities.

For more information please see:

Prism Dimensions

Figure 1 shows the geometry of two-sided wedges can be defined by an angle and a thickness.

Image above: Minimum Specifications for Wedges

Manufacturing Technology

Optimax grinds and polishes prisms from various optical materials for UV, visible and IR applications for use in transmission or reflectance. Materials processed include:

  • All commercially available optical glasses
  • Fused silica plus Low Expansion optical ceramics
  • Crystals including CaF2, BaF2, MgF2, ZnSe, ZnS, sapphire, silicon, germanium
  • Hard ceramics including AlON and spinel
  • Stainless steel

Optimax utilizes deterministic CNC machine tools for complex shaping and a host of conventional processing techniques for chemomechanical planarization. Capabilities include:

  • Double side processing for diameters up to 100 millimeters, producing parts free of detectable parallelism error
  • Continuous lap polishers for diameters up to 300 millimeters, producing parts of lowest roughness and irregularity
  • Cemented assemblies for complex prisms are available with or without image forming surfaces

Prism 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.

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.

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.
  • 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.

Prism 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.
  • 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.
  • 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.
  • 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.

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.

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.

Manufacturing testing

Testing Prisms

Optimax has phase shifting interferometers for precision measurement of flatness plus autocollimators and a Wild Goniometer for precision measurement of angles. Optimax makes transmission flats for interferometric testing of surface irregularity to 50th wave.

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.