Absolute Metrology Services has extensive experience with interferometry and optical testing. Over the past 20 years we have worked with large aperture interferometers and interferometric microscopes, from basic and advanced interferometry training levels to high-level, absolute reference certifications and calibrations. Browse our offerings on this site, or contact AMS directly with your specific needs.
Quality Interferometry Training – Basic and Advanced, On-Site
AMS takes pride in bringing both quality interferometry training and applications engineering into a single, cost-effective package. We have a long record of experience in interferometry training, as well as the high-level engineering experience required to answer your advanced questions “on the spot”.
We encourage hands-on training wherever possible, rotating students through the tasks they need to learn. This constant rotation through the position of ‘operator’ keeps students interested. When material needs to be presented in a classroom setting, we will follow this with a laboratory test of the topic. This reinforces the topic and keeps attention levels at a maximum.
Fifteen years of training experience has shown us that students’ minds tolerate between 4-6 hours of training on any single day. After this time, additional information is not well retained. For this reason, AMS offers the option of full- or half-day training sessions.
Many large interferometry companies hire trainers who must adhere strictly to their course structure, with attendees from multiple companies. More advanced questions or on-site applications engineering usually has to be forwarded to a different person.
AMS brings both interferometry training and applications engineering experience to your site. With AMS interferometry training, your company can enjoy the following advantages:
- Your company receives custom training: AMS can meet with you at your facility to review your testing needs, discuss them via email or phone, or have you choose from a detailed list of topics. We will then design a course to fit your testing needs and schedule. Your groups can be trained during one visit or over multiple visits as needed. At the end of training, training booklets are provided with your desired course topics for future reference.
- Your company saves money: AMS regularly works with the large interferometry companies on their advanced projects, so we bring you the same experience and knowledge at a “small-company” cost. Because you are being trained by an optical engineer, we can answer your advanced questions on the spot, bring up new controls and plots when needed, and identify accuracy limitations in your setups (and solutions) during the same visit.
- Production is not interrupted: Since we offer on-site training, employees can exit and enter the training as needed to continue production. We offer half-day training options so that some employees can be trained while others keep your machines running. The two groups can switch places for the second half of the day.
- Your company is connected: AMS can identify any interferometry hardware or software needs, and transmit these needs directly to the appropriate sales representative. We have experience working with the major interferometer companies including Zygo and 4D.
Interferometry Courses
AMS can build a customized course from the topics below, or you can choose to be trained on an entire group of topics. If you don’t see a desired topic on this list, contact AMS. We develop course material as needed, and it is beneficial for AMS to work with real parts and software to write these materials.
Large Aperture Interferometry (2″ and larger)
Large Aperture Training, Basic Topics 1 : For users wishing to learn proper general use of a large-aperture Fizeau interferometer, these topics include the basic concepts of wave motion, how this forms fringes in an interferometer, proper alignment and focus of plano surfaces, correct choice of transmission sphere f/number for a spherical surface, and proper alignment and focus of convex vs. concave surfaces. Software controls covered include setting up masks, lateral calibration, and the most commonly used measurement controls, analysis controls, plots, and results.
Large Aperture Training, Basic Topics 2 : For a more complete ‘Basic’ course, these topics can be added as desired. They include how light interacts with surfaces (reflection and refraction), Newton vs. Fizeau interferometry and fringe contrast. Software coverage includes evaluating spikes in data, filtering methods, discussions of when and how much to filter, use of Auto Sequence and Process Stats functions, PV and RMS results vs. ISO specifications, “auto-load” settings, acquire masks, and application locking. Setup considerations include using aperture matching vs. zoom, improving TF/TS alignment, improving low fringe contrast, correcting for automatic gain control (AGC) errors. Other practical issues include reduction of backreflection and secondary fringe pattern effects, Error reduction reviews reference surface errors, turbulence and temperature-related errors, and tilt-induced errors. Scaling topics include correct use of interferogram scale factor and scaling results for other wavelengths.
Large Aperture Training, Application-Specific Topics : These topics can be covered as needed. Testing lenses in transmission includes finite vs. infinite conjugate testing, alignment techniques for each, and errors introduced due to misalignment. Radius of curvature topics include radius vs. sag specifications, methods of radius measurement (digital scales, encoded scales, and distance-measuring interferometers), error sources (null errors, Abbe errors, environmental errors, and alignment errors), and alternate setups for testing very long radii. Angle measurement topics include testing wedge angle in both transparent and opaque samples, and measuring both TWE and angle errors in corner cubes, prisms and rhomboids.
Large Aperture Training, Advanced Topics : These topics are recommended for users who are already familiar with the basic topics. Optical topics include a review of imaging systems and third-order aberrations, in both wavefront deformation and image effects. Error reduction and correction includes more in-depth coverage of ray-mapping errors, distortion errors, reference surface errors, environmental errors, and testing to adjusted specifications based upon these errors, where applicable. Hindle setup testing includes alignment and testing of ellipses, parabolas and hyperbolas, including the use of reference spheres / balls. Aspheric testing includes non-null testing, testing with refractive and diffractive nulls, proper use and alignment of computer-generated holograms (CGHs), subaperture zone scanning, and configurable null stitching. Extended sources include proper use, advantages and limitations of the ring and disk sources. Software use includes the use of advanced plots and controls, Zernike polynomials, and Legendre polynomials.
Additional Topics: AMS has trained customers in many more topics not listed above. Contact AMS for training information on the proper use of FlashPhase, VeriFire MST with FTPSI (Fourier Transform Phase Shifting Interferometry), Wavelength-Shifting Interferometry (WSI), or if you do not see your topic of interest listed above.
Interferometric Microscopy
Microscope Training, Basic Topics : This list is currently being updated. Please visit our site shortly, or contact AMS if you would like us to send you a copy.