Glass charts are typically required when:
The existing chart has been severely chipped or brokenThe lines on the existing screen have faded or worn off
The new chart will remain in the comparator for an extended period of time.
Optical comparator overlay charts
Overlay charts are made of plastic and are placed over the existing glass screen. They are typically required when charts are interchanged on a frequent basis. Dorsey Metrology offers 4 types of plastic overlay material:
- .007" thick clear mylar
- .007" thick frosted mylar
- .050" thick clear vinyl
- .050" thick frosted vinyl
Optical comparator scales
Dorsey Metrology also offers three types of optical comparator scales:
The inch/decimal and decimal/metric scales are available in glass and are useful for sight verification. The multi-magnification scales are useful for direct screen measurements of projected images on a comparator that is not equip with either digital readouts or micrometer readers. These scales are available in glass or 050" thick vinyl. All optical comparator scales are traceable to the N.I.S.T. Certification sheets specifying traceability are available at no extra cost. Glass scales are available with serialized numbers. All scales are intended for sight verification and not for comparator calibration.
How to order a chart for your optical comparator?
When ordering your optical comparator chart, please have the following information available:
- style of chart
- type of optical comparator and model number
- lens magnification
- chart material
- any additional information required for a particular chart or scale
In addition to standard comparator charts, we have the ability to provide custom charts of any nature, regardless of complexity or size. Charts are designed on a CAD system from your drawings, plotted on precision machines, and reproduced on the same materials available for our standard charts. If you design your own charts but lack reproduction facilities, we can produce your CAD data and provide you with a finish chart at a significant reduction in cost. Custom comparator charts are also traceable to the N.I.S.T. certification sheets specifying traceability and are available upon request at no additional cost.