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Zygo GPI & Verifire Update

Recent additions to the GPI and VeriFire Accessories product lines have been the introduction of higher quality Transmission Spheres, Transmission Spheres with DynaFlect Coatings and a lower cost Interferometric Radius Slide.


Higher Quality Transmission Spheres

Standard Transmission Spheres have been supplied with a 1/10 wave (lambda/10) surface form error up until recently. Now all 4" Transmission Spheres (f/0.65, f/0.75, f/1.5, f/3.3, f/7.2 and f/11) can be supplied with 1/15 wave and 1/20 wave surface error.

DynaFlect Transmission Spheres

DynaFlect coatings on Transmission Flats have been around for a number of years. These coatings allow the user to measure highly reflective parts (>40% reflectivity) without having to use an Attenuation Filter (AF) and have the advantage of having a surface error of only 1/20 wave. As you may be aware Attenuation Filters are fragile and have a transmitted wavefront error of <= 1/10 wave and therefore add to the uncertainty of the measurement. DynaFlect Flats have been particularly useful for measuring mirrors.


Only recently have DynaFlect Transmission Spheres become available for f/0.75, f/1.5, f/3.3, f/7.2 and f/11 TS's with 1/10 wave surface error. These allow the user to measure highly reflective spherical surfaces such as contact lens inserts, prosthetic implants (hip joint replacements) and spherical mirrors. The other major advantage in not having to use the Attenuation Filter is when measuring fast convex surfaces. The maximum radius that can be measured with a f/0.75 TS with AF fitted is 26 mm and only 10 mm with a f/0.65 TS with AF fitted. In contrast, the maximum radius that can be measured with a f/0.75 DynaFlect TS is 44 mm!

More info here.


New High Accuracy, lower cost Radius of Curvature Measurement Accessory

Zygo have offered an Interferometric Radius Slide (IRS) based on their highly specified ZMI-2000 Displacement Measuring interferometer system for some years. Replacing this with one based on the lower cost ZMI-510 System has lowered the cost with little impact on performance. The major advantage of using an IRS is that the radius of curvature measurement is made on-axis thereby minimizing Abbe error that is the major source of error for these measurements using Radius Scales. Please refer to Zygo's note below, "About Resolution and Accuracy"


About Resolution and Accuracy

Resolution is the smallest increment that is recognized by the scale. Accuracy is a measure of the statistical error in the readings that are obtained. Accuracy depends upon many factors, such as: the straightness of the guide bar, the flatness of the table or granite, the installation and alignment of the scale to the interferometer, and environmental conditions.


Options

Radius of Curvature Option


Digital Radius Scale

Short Radius Kit, 150 mm

Encoded DRS, 1 meter

Encoded DRS, 2 meter

Interferometric Radius Scale


Accuracy Range
=200 µm

10-20 µm

25-75 µm

50-150 µm

the greater of 3 µm or 0.001%


Typically, the smaller the radius of the part, the greater the accuracy of the measurement. More info here.

For more information on these products and other accessories, please reply to this email and ask for the latest version of the GPI and VeriFire Accessories brochure to be sent to you.


Please note that most of these accessories are backward compatible with the PTI and Mark series of Zygo Interferometers. If in doubt, please ask.


For more information, on the Zygo range of products, visit the Zygo Web page.

To Lambda's Zygo and Metrology Web Page to learn more about Zygo products available in the UK and Ireland from Lambda Photometrics.

To contact Lambda Photometrics contact@lambdaphoto.co.uk or simply call 01582 764334 and ask for Ken Middleton, Zygo GPI Product Specialist.