The ISO Element Drawing represents an ideal way of specifying a system's elements for production. This article provides an overview of this tool and demonstrate its use in the case of a simple singlet.
Authored By Sean Lin
Introduction
In order to specify an element for production, the optical engineer needs to provide the manufacturer several information, such as the element radii, thickness, material, diameters, etc., together with all the associated tolerances. For this purpose, the ISO Element Drawing may be used to create an ISO 10110 compliant drawing for single surfaces, singlets or doublets. The output is ideally suitable for use in optical shop fabrication, as this standard is widely used in the optics manufacturing industry.
Introduction to ISO Element Drawing
In this article, we will describe the ISO Element Drawing tool for a simple singlet. The output of the tool is a cross section drawing of the element, alongside relevant information on its physical characteristics and tolerances.The file used here is provided in the Article Attachments. It's a 75 mm focal length singlet, for which the tolerances have been already defined.
The ISO Element Drawing is located under the Tolerance tab, in the Manufacturing Drawing and Data section.
As a first step, expand the tool settings, and in the General tab select the first surface of the element to be drawn. Next, select the component as surface, singlet, or doublet. In this example, the component is at the second surface and it is a singlet lens.
Other than the General tab, note that each surface in the element (Left and Right surfaces in this case) will have two tabs each, allowing users to enter data corresponding to ISO 10110 drawing codes 3-4 and 5-6. “Codes 3-4” include Radius, Conic, Effective Diameter, Diameter, Diameter (flat), Coating, Form and Centering Errors. “Codes 5-6” include Imperfections, Laser Damage, Texture, Chamfer and other surface specifications.
Note that some of the element characteristics are pre-populated when running the tool, as by default data available in the Lens Data Editor is automatically copied to the ISO Element Drawing.
By unchecking the Automatic button, data in the Codes 3-4 tab can be overwritten if required:
Other surface and material characteristics are left for the user to fill in as appropriate.
Note that the ISO Element Drawing uses a naming convention for the diameters which is different from the Lens Data Editor (LDE). For OpticStudio Premium and Professional, the mapping of the diameter values is as follows:
- Effective Diameter = Twice the Clear Semi-Diameter or Semi-Diameter value in the LDE
- Diameter = Twice the Clear Semi-Diameter or Semi-Diameter + Chip Zone values in the LDE
- Diameter (flat) = Twice the Mechanical Semi Diameter value in the LDE
If using the ISO Element Drawing with a Singlet or a Doublet, one extra “Material” tab for each element will be present. This tab includes properties of the material: name of the Glass, Index of refraction, Abbe number, Thickness, Stress Birefringence, Bubbles, Inhomogeneity, and other material specifications.
For a detailed description of ISO 10110 symbols and drawing codes used in the ISO Element Drawing, please refer to help file section The Tolerance Tab ... Manufacturing Drawings and Data Group ... ISO Element Drawing (manufacturing drawings and data group)
Note that, for singlet elements, OpticStudio will produce XML output to facilitate sharing ISO 10110 data. The XML output is visible on the “XML” tab, at the bottom of the ISO Element Drawing window.
In the XML output, element and attribute fields are populated based on the values that are entered in the ISO Element Drawing settings dialog and in other data locations in the lens file. The XML output data may be saved to a file using the “Save As” button on the General tab.
Tolerance data in the ISO Element Drawing
Tolerance data can be directly entered in the ISO Element Drawing settings, by manually populating the appropriate “- tol” and “+ tol” columns, as well as relevant error entries, such as Form error. However, if you have already completed a tolerance analysis, then tolerances are already specified in the Tolerance Data Editor (TDE). In such cases, tolerances can be simply imported from the TDE by clicking “Reset from TDE”, in the General tab.
When “Reset from TDE” is pressed, tolerances on surface radius, form, tilt and decenters, and on material thickness and index are taken from the TDE. Note that only operands TRAD, TCUR, TFRN, TCON, TTHI, TIND, TABB, TSTX, TSTY, TSDX, TSDY, TIRR, TEZI, and TWAV are considered. If a tolerance is not provided, then it’s set to zero in the ISO Element Drawing settings, and it will not appear in the drawing.
Below is a list of the tolerancing operands used in the sample file provided, and where is the tolerance translated in the output of the ISO Element Drawing.
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TTHI, is a tolerance on the thickness, hence associated with the relative position of surfaces. In this example, this represents a tolerance on the singlet thickness, and therefore appears in the Material tab of the ISO Element Drawing. In the output, this tolerance is shown in the cross section drawing itself, where the Thickness is specified.
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TRAD is used to tolerance directly the radius of curvature, so it appears in the Code 3-4 tab of the ISO Element Drawing. In the output, this tolerance is shown in the first line of the relevant surface properties, where the value of the Radius is specified.
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TIRR is used to tolerance surface irregularity, and it also appears in the Code 3-4 tab of the ISO Element Drawing. In the output, this tolerance is shown in the surface properties, close to the “3/” entry, which represents form tolerances. Note that TIRR operand is specified at a given test wavelength (specified via TWAV operand), so the test wavelength is also reported close to the irregularity value.
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TSDX and TSDY are used to tolerance surface decentration in X and Y, while TSTX and TSTY are used to tolerance surface tilts about the X and Y axes. These operands also appear in the Code 3-4 tab of the ISO Element Drawing. In the output, this tolerance is shown in the surface properties, close to the “4/” entry, which represents centering tolerances. It should be noted that TSTX and TSTY are specified in degrees, while the ISO Element Drawing output displays both tolerances in minutes of arc.
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TIND is the tolerance on index of refraction, and appears in the Material tab of the ISO Element Drawing. In the output, this tolerance is shown in the second line of the material properties, where the value of the refractive index is reported.
Finally, note that tolerancing operands TEDX, TEDY, TETX and TETY (representing the element decenters and tilts) are not reported in the ISO Element Drawing. These are assembly tolerances and can’t be specified in the drawing for a single element.
More detailed information about the tolerancing operands described above can be found in help file section The Tolerance Tab ...Tolerancing Group...Tolerance Data Editor...Tolerance Operands.
References
- “ISO 10110 Optics and Optical Instruments - Preparation of drawings for optical elements and systems: A User's Guide”, by Ronald K. Kimmel and Robert E. Parks, eds.
- OpticStudio help files
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