Having Confidence in Fizeau Interferometers Relies on Quality in Both the Design and Manufacturing of Key Components

Fizeau interferometers are used to measure the shape and quality of optical surfaces with high precision by comparing the optic under test to a reference optic.1 However, it is important to remember that not all reference optics are created equal, as design and construction may cause quality fluctuation. When using reference optics to assess the quality of other optical surfaces, it is essential to have confidence in the quality and precision of the reference optics.


UltraFlat and UltraSphere λ/40 Transmission Elements

Fizeau interferometers have applications in the manufacture of optical components, the validation of system performance, and the measurement of both flat and spherical surfaces. These applications are relevant in a number of fields, from telecommunications to astronomy. NASA itself offers a guide for the manufacture, alignment, and validation of system performance in Fizeau interferometers.2 Their methodology affirms that making the highest quality measurements requires use of the highest quality reference optic. Without it, users cannot have confidence in the quality of the tools they rely on every day. That means essential certifications can be unreliable, test results can be corrupted, and valuable components can be manufactured imprecisely. Therefore, ensuring consistent quality hinges on understanding how interferometers function.

Interferometers function by taking measurements in an optical arrangement of two or more beams that originate from the same point but pass through a beamsplitter, leading them to take different beam paths. One beam tests the object in question for aberrations, quality, and so on. The second beam waits for the other to return and cross paths, leading to interference that allows a viewer to see a high-quality image of the optic surface. This process relies on high quality reference optics for accurate information, as those of low quality can undermine the entire process. So how can you be confident your measurements are precise?

Designed and manufactured by ZYGO, the UltraFlat™ line of transmission flat reference optics gives users confidence in the precision of their measurements and the quality of their products. Able to perform in either a vertical or horizontal orientation, the full-area calibration of UltraFlat reference optics quantify residual errors in the precision reference surface. In fact, UltraFlat reference optics are certified at λ/40 or better. That means that, coupled with software, ZYGO's design allows for the correction of these errors, further boosting user confidence in their interferometers precision. ZYGO has invested over 40 years of experience into the creation of an industry-standard in applications and fields of all kinds.

Learn more about UltraFlat reference optics today by downloading ZYGO's Laser Interferometer Accessory Guide.

  • Introduction to Interferometric Optical Testing
  • Guideline For Use Of Fizeau Interferometer In Optical Testing