OPTIMAXSpheres
Spheres, the most common type of optic,
have at least one surface that
is a segment of a ball. Spheres are 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.
OpticianAdvice
In lens designs with a long concave radius where a mounting annulus is needed, it is recommended to add a step and a minor diameter specification. This makes fabrication less complicated and can therefore help to lower cost. Follow this link for more basics regarding Mechanical Attributes of a Lens.
If the metrology to be used is test plating, the optical designer should fit the design to the manufacturer's test plates and re-optimize. Fringes of power relative to the fitted test plate radii are the units of choice for tolerance in this situation. For interferometric radius measurement, the optical engineer may wish to update the optical design model with measured radius data from each completed optic and re-optimize the lens.
For some systems, a cost effective option may be using a corrector plate. A corrector plate is an optic that is made to correct the wavefront for a lens system's residual irregularity. The irregularity tolerance for each lens can be loosened, reducing cost, when a corrector plate is to be used for the system. The system is assembled, total irregularity measured, and a final lens, the corrector plate, is designed that corrects for the system's overall irregularity errors. Optimax can manufacture the corrector plate after the system performance or transmitted wavefront error (TWE) has been evaluated and the corrector plate is designed. This method is sometimes better for overall system performance and cost. More information on using a corrector plate is provided in the Optimax paper Improving Lens Performance with TWE Testing.
Considering the application of the lens or lens system and determining the acceptable amount of aberration before setting a tolerance on irregularity is important as it will significantly affect the cost of the optic. For more insight on tolerancing see The Cost of Tolerancing.
Manufacturing Technology
Optimax utilizes deterministic CNC machine tools for predictable removal rates and adherence to tight tolerances. To control wedge, precision tools that maintain the optic axis are used. Optimax grinds and polishes most optical materials such as glass, fused silica, and crystals for UV and IR applications.- Spheres are available in the following shapes: bi-convex, bi-concave, plano-convex, plano-concave, meniscus, and dome.
- Cemented assemblies, such as doublets and triplets, are available.
- Most common optical glasses for UV, Vis and IR: Fused Silica, BK7 and SFL6.
Testing Spheres
Optimax has one of the largest test plate libraries for making spheres. These test plates are certified to +/- 0.01%. As required, Optimax can make test plates for special radii. Optimax makes transmission spheres for interferometric testing of surface irregularity to 50th wave. Mechanical attributes such as outside diameter, center thickness, and sag affect lens performance. Appropriate lens tolerances are provided by Optimax in the Manufacturing Tolerance Chart to ensure proper lens function.Coating Capabilities
Our coating chambers include four electron-beam coaters supported by a Perkin-Elmer lambda 900 Spectrophotometer. Optimax offers BBAR, V-coat, and mirror coatings; custom coatings are also available. For more details please see our coatings data sheet.Quality Assurance
Optimax inspects 100% of all optics. Test data is provided with prototype orders. The use of state-of-the-art metrology guarantees customer satisfaction.Fast Delivery
Optimax specializes in manufacturing a wide variety of optical components. In all cases, on-time delivery is crucial. A money back guarantee is offered for all expedited deliveries.OpticianAdvice
Optical Material Selection
When selecting an optical material some consideration should be given to availability of the material. Many optical glasses are available off the shelf or within a few days, while others may take weeks to receive. Optimax provides a list of Preferred Optical Glasses to designate the materials for which we maintain an inventory. For optical designs requiring larger lenses, say bigger than 140mm diameter, material availability should be confirmed. Many optical glasses are made in slab form 140 to 200mm wide.Optical Component Tolerancing
One of the most difficult aspects of optical design is to master lens tolerancing. It's a difficult task to minimize cost while ensuring good optical performance. A recent collaboration between an optical engineer, an optics manufacturer and a metrologist yields valuable insight for tolerancing optical components - The Cost of Tolerancing. The paper compares several methods for tolerancing an optical system and reveals that Optimax Precision Tolerances are a reasonable compromise for containing cost while ensuring good optical performance.Mechanical Considerations
To minimize manufacturing difficulties in achieving the irregularity tolerance, the designer should try to avoid lens shapes with a thickness less than 10% of the diameter, i.e. 10:1 (d:t) aspect ratio. Likewise, thin edges should also be avoided due to their propensity for chipping.In lens designs with a long concave radius where a mounting annulus is needed, it is recommended to add a step and a minor diameter specification. This makes fabrication less complicated and can therefore help to lower cost. Follow this link for more basics regarding Mechanical Attributes of a Lens.
Radius Tolerancing
Interferometry has eliminated the dependence for power to be based on the irregularity specifiaction, so the modeled radius tolerance may be applied in full independent of irregularity specified. Radius can be toleranced using fringes of power OR stated as a linear radius tolerance. In the end, specifying only one is sufficient and one can be converted into the other. Except when tolerancing a plano surface, Power is still useful because a radius tolerance there is meaningless. If both are specified, an explanation should be provided to the manufacturer.If the metrology to be used is test plating, the optical designer should fit the design to the manufacturer's test plates and re-optimize. Fringes of power relative to the fitted test plate radii are the units of choice for tolerance in this situation. For interferometric radius measurement, the optical engineer may wish to update the optical design model with measured radius data from each completed optic and re-optimize the lens.
Surface Irregularity
Tighter tolerances on irregularity can be a major cost dirver in producing a lens. Surface irregularites introduce aberration into an image due to disruptions from the expected path of light, so a more uniform surface is preferred. However, it is important to realize that while the image quality of a lens systems is an accumulation of the manufacturing errors, those errors are positive and negative. Therefore, the individual surface tolerances do not need to be wavefront quality divided by the number of surfaces. It is important to model and predict the image quality of the system as a whole considering all factors. For illumination systems, an irregularity tolerance of 2 fringes might be sufficient, but a tolerance of less than 1 fringe is often desired for high quality imaging systems. Different types of irregularity have varying effects on image performance.For some systems, a cost effective option may be using a corrector plate. A corrector plate is an optic that is made to correct the wavefront for a lens system's residual irregularity. The irregularity tolerance for each lens can be loosened, reducing cost, when a corrector plate is to be used for the system. The system is assembled, total irregularity measured, and a final lens, the corrector plate, is designed that corrects for the system's overall irregularity errors. Optimax can manufacture the corrector plate after the system performance or transmitted wavefront error (TWE) has been evaluated and the corrector plate is designed. This method is sometimes better for overall system performance and cost. More information on using a corrector plate is provided in the Optimax paper Improving Lens Performance with TWE Testing.
Considering the application of the lens or lens system and determining the acceptable amount of aberration before setting a tolerance on irregularity is important as it will significantly affect the cost of the optic. For more insight on tolerancing see The Cost of Tolerancing.