Direct Optical Research Company specializes in the design and manufacturing of non-contact interferometers for the optical fiber and connector industry. DORC's range of ZX-1 Zoom Interferometers and Phase Measuring System (PMS) software has been specifically designed to meet the ever-increasing need for accurate, automated, high volume testing of ferrules, ferrule blanks, connector assemblies, pigtails, patchcords, array connectors and optical fiber cleaves.

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 fixed magnification objectives.

DORC’s unique patented design allows the system to acquire both interferometric and inspection images from the same measurement. While the interferometric data is used to calculate the surface topography, the inspection image is processed simultaneously using our exclusive Scratch Analysis algorithms. Categorizing every scratch by region, length, width, height and surface area, this feature not only eliminates the need for a separate visual inspection step, but also eliminates any operator subjectivity of visual defects.  

Using DORC's Windows XP^® Professional based Phase Measuring System (PMS) software, it is possible to automatically acquire and calculate all of the important surface topography parameters with extreme accuracy and repeatability in less than a second. Available parameters include radius, apex offset, fiber height, angle, key error and fiber/ferrule surface roughness.

To perform a measurement, the operator simply inserts the connector under test into the chuck, optimizes the focus and initiates the measurement. The ZX-1 will then automatically acquire phase shifted images and calculate all of the important parameters of the sample, printing and/or storing all of the results as predetermined by the system setup menu. Being completely automated makes the system operator independent, eliminating any subjectivity as to whether the connector has passed or failed the quality control testing. Using the password protected setup menu’s, the quality control manager can adjust all pass/fail criteria of each parameter relating to a particular type of connector. Other variable parameters available within the setup menus permit  compliance with all "Standards Organizations" measurement methods worldwide.

Once a measurement has been completed, the operator can choose from a diverse range of graphical presentation formats. The PMS software also offers an extensive range of reporting, archiving and statistical analysis capabilities by porting measurement data and images directly to Excel 2000^®. Naturally, this familiar format offers significant advantages for additional post processing and distribution of measurement data.