ZX-1 mini Zoom Interferometer
DORC's implementation of the Michelson Interferometer incorporates an electronically controlled zoom objective. Fringes created by introducing an internal reference path can be analyzed to measure the surface topography of a connector or fiber endface. The fully enclosed vibration and contamination resistant Michelson configuration eliminates the requirement for the delicate surface of the sample under test to be in physical contact with the measuring equipment. Being non-contact not only avoids contamination of both the sample and interferometer, but also removes the possibility of contamination induced measurement errors.
Another advantage of the Michelson configuration is the ability to isolate the reference mirror, adjustment of which is used to calibrate the apex offset, to a location inside the systems housing. Systems using interferometric objectives are placed at a distinct disadvantage by not having this capability. Firstly, they cannot "block" the reference mirror to produce an inspection only image, and secondly, since the reference mirror in interferometric objectives cannot usually be adjusted, apex offset calibration is performed by making very small "pitch and yaw" adjustments to the connector fixturing. Adding these two additional axis of freedom to a stage already containing XYZ and tilt adjustments, can lead to significantly poorer apex offset measurement repeatability.
The parfocal/parcentral zoom objective ensures that the image and reference paths remain in focus and centered throughout its entire magnification range. The operator can instantly switch between inspection and interferometric modes at any magnification without refocusing, thereby displaying the optimum number of fringes - regardless of the samples unique surface topography. Precision XYZ and tilt adjustment of the sample, combined with the inherent advantages of using a zoom lens, allows this system to measure a much larger range of sample types, and capture details that would be missed by conventional systems using single or multiple fixed magnification objectives.
By adding the tilt option to any quick change chuck assembly, the ZX-1 can measure a sample which has any angle between zero and fifteen degrees. When this is combined with a comprehensive range of keying adapter plates, the ZX-1 can measure any combination of angled or straight connectors, in any style without having to recalibrate the system.
DORC/Direct Optical Research Company, 734 West Highland Avenue, Phoenix, AZ 85013. Tel: 602-279-2099; Fax: 602-279-2025.