Measuring Prisms: Multiple Wavefront Channels In One Setup

Prism Stacks Produce Multiple Wavefronts

Prism stacks are difficult or even impossible to measure with a laser interferometer, yet are easy to measure with Spectrally Controlled Interferometry (SCI).

Examples of prism stacks for projector imaging systems, displacement measuring, monolithic or assembled component interferometers, and RGB combiners.

Laser Interferometer Back Reflections

A laser light source interferometers (for example a laser Fizeau) create fringes from every back reflecting surface. In some prism assemblies these are created in multiple channels and are superimposed creating confused interference patterns that are impossible to measurement.

Spectrally Controlled Interferometry Eliminates Back Reflection

Spectrally Controlled Interferometry (SCI) can selectively isolate the interference cavity of interest for easy and accurate measurement. And as opposed to white light “delay line” interferometers, SCI is easy to align alignment prior to measurement using its long coherence alignment mode.

Imaging System Prism Stack

In an imaging prism stack the transmitted wavefront passes through several back reflecting surfaces, see figure 1. In this case there are four potential back reflection surfaces. SCI can measure each of these independently if the surface is of interest, or only the transmitted wavefront without corruption. This allows a straight on measurement without tilting or distorting the wavefront.

Figure 1: Schmidt-Pechan Prism. The circled interfaces are areas where back reflections can prevent accurate measurements with a laser interferometer. (ref. https://commons.wikimedia.org/wiki/File:Schmidt-Pechan_prism.svg)

Displacement Measuring Interferometer Components

Interferometers for displacement measurement typically have multiple channels for the test and reference beam path. SCI enables the measurement of each channel independently, without the degrading influence of multiple entry and exit surfaces. To select the measurement channel cavity the polarization is rotated by 90º from one to the other, which is accomplished at the interferometer. [A linear polarized interferometer, where the polarization can be rotated, is used for this application. Contact ÄPRE for more information.]

Figure 2: a-WOW Interferometer for measuring displacement and angle. (ref. Loughridge, Russell & Abramovitch, Daniel. (2013). A tutorial on laser interferometry for precision measurements. Proceedings of the American Control Conference. 3686-3703. 10.1109/ACC.2013.6580402.)

RGB Prism Combiners

RGB (red-green-blue) prism combiners are particularly difficult to measure. The three channels must be separated to measure each path’s transmitted wavefront, yet optically they are co-axial. With a laser interferometer this is impossible, as all the wavefronts overlap, see figure 3. Plus there are multiple back reflecting surfaces that must be eliminated for an accurate measurement. Each channel can be aligned independently in the long coherence align mode. Then selected in the short coherence mode for accurate measurement.

Figure: 3: Dichroic Prism for RGB selection. The red circle indicate surfaces that reflect back into the interferometer confusing or suppressing the measurement.

Interferometer resolution

Many RGB prism combiners are classed as micro-optics with a less than 6 mm clear aperture. Therefore a standard 4 inch (100 mm), zoomed imaging interferometer with ~400µm image resolution or worse at all zoom magnifications, has insufficient image resolution. A minimum of 60 µm image resolution is required to measure the wavefront of a 6 mm clear aperture prism. 60 µm resolution yields a 100 X 100 image resolution across a 6 mm clear aperture.

Figure4: Image resolution demonstrated for 100 mm aperture interferometer. Airy disk size properly sampled at ≥Nyquist limit is required

NOTE: This is not 100 X 100 pixels but image resolution. The camera array must be 2X this or a minimum of 200 x 200 pixels AND the imaging optics must produce an airy disk size of 60 µm. At 100 X 100 image resolution 36 Zernike polynomials are accurately calculated. See Figure 4.

Shown in figure 5 is ÄPRE’s S6|HR interferometer with 15 µm image resolution capable of measuring the transmitted wavefront in components to 1.5 mm clear aperture.

Figure 4: ÄPRE S6|HR interferometer with SCI light source for measuring micro-optics including prisms and prism assemblies.

Spectrally Controlled Interferometry Separates the RGB Channels

Again with a laser interferometer the three channels create back reflections simultaneously making the measurement impossible. In the measurement set up (see figure 5) each six prism assembly cavity has three cavity of different optical path lengths. Therefore the distance between the test and reference flat is different for each channel. With SCI each channel is selected one-at-a-time. Typical measurement results with SCI and S6|HR are shown in Figure 6.

Figure 5: RGB Prism assembly setup with S6|HR Interferometer.

Figure 6″ Typical results measuring an RGB prism assembly with S6|HR and SCI. One setup three results in seconds.

Summary

Prisms assemblies are difficult optical elements to measure. Back reflections from multiple surfaces and multiple channels make laser interferometry incapable of making these measurements. SCI offers an easy to use, accurate method to measure these components for the first time.

More Applications >

S6|HR Interferometer Specification>

Learn More about SCI>

Applied Optics Paper >

Let’s Talk>

April 6, 2016January 4, 2018

Fizeau Interferometer: Buy or Upgrade; what are the purchasing options?

Fizeau Interferometer Buyers Guide 9

This blog is about the performance and price options for laser Fizeau interferometers

Up to this point we have been discussing how various applications require specific interferometer sensor configurations and features. Now comes the key point when you need to do something. Do you need increased production capacity? Has a new process been introduced that requires better feedback? Is the IT department concerned about an old operating system? Has the computer failed, or the system has become unreliable but meets your production needs? Do you have a new program that requires a dedicated system? Or your customer is pushing for a result your system does not produce. What do you do? Do you buy a new interferometer? What are the options?

Buy New, Upgrade or Buy Refurbished?

Asking some questions can lead you to the purchasing options to consider.

Is the system to support a spot polishing process where slopes and mid-spatial frequencies are important?
- Yes – indicates a high performance imaging interferometer with a 2K X 2K level camera, low distortion and low ray-trace errors.
Is the environment harsh, with vibration and air turbulence present?
- Yes – indicates a SPMI (Multi-detector or Carrier Fringe acquisition) system
Does your application require custom fixturing, a special wavelength or non-standard aperture?
- A custom system is required – talk to the various providers regarding your best option
Does the system support a standard lap polishing process where form is the key measurand?
- Yes – indicates a classic interferometer

High Performance Imaging System laser Fizeau

These are the latest technology and will meet all the requirements for most situations, the problem is they tend to be expensive. Not only do they image mid-spatial frequencies well, the associated low ray trace errors mean they are suitable for carrier fringe data acquisition for operation in harsh environments. The major drawback is price. Most systems are 1.5X to 2X more expensive than a classic interferometer. If they were the same price everyone would probably buy one of these interferometers.

Harsh Environment laser Fizeau or laser Twyman-Green

There are several interferometers available that meet this need using both carrier fringe and multi-camera or multi-pixel configurations, Many of these applications have specific specifications that dictate size, weight, and result output. It is best to discuss these with the manufacturer to arrive the best choice.

Classic laser Fizeau Interferometer

With the classic Fizeau there are the most choices.

Buy New or Refurbished: Increase Production Capacity

If increased production capacity is required there are two choices: Buy new or refurbished. There are a few choices for new systems that have the same optical system as produced for the last 30 years – with extensively upgraded software! These new system are priced between $60,000 and $75,000 (USD).

Also available from time to time are refurbished interferometers with the same/similar classical optical design. These refurbished systems have the latest data acquisition and analysis software like a new system and are priced between $33,000 and $37,000.

Upgrade: Failed System, Old Operating System, New Acquisition and Analysis Software Required

There are thousands of interferometers installed worldwide that can be renewed by upgrading the electro-optics and software. These systems can operate as well as a new system, with the latest software, cameras and computer systems. Upgrading is cost effective and is priced between $22,000 and $27,000. Upgrading is usually the best choice when production capacity is not an issue, but systems are down. A side benefit is the increased efficiency of new electronics can also increase the throughput and therefore production capacity of existing systems.

Summary

There are several purchasing options available regarding laser Fizeau interferometers. Applications often drive the decision but price is also important. laser Fizeau Relative Pricing

February 23, 2016March 13, 2018

Harsh Environment Testing: Optical Towers and In-situ Metrology – Buyers Guide Chapter 6

In this blog measurement of optics in a harsh environment with a Fizeau interferometer is discussed.

For large systems, typically telescopes, vibration and air turbulence hinder or prevent the measurement phase by temporal phase shifting. Also interferometers placed on machine tools to measure in situ experience a vibrating environment. When vibration and turbulence hinder measurement then only a simultaneous phase measuring system (SPMI) will be able to acquire data. These systems acquire phase data fast enough to freeze fringe motion due to vibration and turbulence.

SPMI Data Acquisition: Multi-Camera and Carrier Fringe

There are two primary SPMI data acquisition architectures: Multi-camera¹ and carrier fringe² . Multi-camera uses polarization to split the intensity data into multiple images with shifted phases which are analyzed for wavefront phase. Carrier fringe uses tilt in the wavefront coupled with several different analytical approaches to extract phase. Both approaches are successfully employed commercially, and are functionally and performance equivalent.

Tower for testing large mirrors at the University of Arizona

Averaging is Required

The SPMI system enables phase to be acquired, but the phase is changing rapidly and by large amounts and any single measurement is meaningless. To achieve stable data, averaging must be employed. The amount of averaging required is a function of the frequency and amplitude of the vibration and turbulence. A useful method to determine how much averaging is required is to acquire 100 data sets in a series as would be performed in an average. Calculate the RMS or P-V of this data set, divide the RMS or P-V by the measurement repeatability desired to obtain a ratio. Square this ratio and set the average to this squared value. For example, if the single measurement repeatability is 6,000 nm P-V and desired is 60 nm P-V then 1002 averages must be taken, at a minimum, to achieve 60 nm P-V repeatability, assuming a gaussian distribution. It is often practical to stir the air with a fan to improve convergence, which can take many hours for large cavities with slowly moving fringes. SPMI systems can often acquire and calculate phase in seconds so averaging can be rapid.

Repeatability is Not Accuracy

Finally, note that repeatability is not low measurement uncertainty, or accuracy. Measurement uncertainty is primarily driven by the optical design of the interferometer, temperature variations in all the optics, mechanical stresses in mountings and optical misalignments and null lenses errors – a la Hubble. Controlling these is much harder than averaging and is a topic unto itself.

SPMI Interferometers are Non-Common Path – Hence Lower Accuracy

Also note SPMI systems are non-common path systems – the polarization paths are different or tilt exists between the test and reference wavefronts. These differing paths degrade the optical performance compared to PMI which can be common path, i.e. the test and reference beams perfectly overlap when a sphere or flat is measured in a nulled condition. So from an accuracy point of view PMI- nulled can outperform SPMI, but when data cannot be acquired due to turbulence or vibration then SPMI is required and an accuracy compromise is acceptable.

Summary

Acquiring data in harsh, vibrating and turbulent environments requires an SPMI data acquisition interferometer. Achieving high accuracy results requires careful attention to the all measurement parameters and is typically of lower accuracy than a nulled laser Fizeau phase shifting interferometer in a quiet environment.

¹ Smythe, R & Moore, R; “Instantaneous Phase Measuring Interferometry”, Opt Eng, Jul/Aug 1984, 25(4):361 – 364

² Takeda, M. “Spatial-carrier fringe-patter analysis and its applications to precision interferometry and profilometry: an overview, Ind Metrol 1990;1(2):79-99

February 9, 2016April 24, 2020

Spot Polished Spherical and Flat Optical Components – Buyers Guide Chapter 5

In this blog the measurement of spherical and flat optics with a Fizeau interferometer that have been spot polished is discussed.

Spot polishers require improved performance over interferometers with standard 6X continuous zoom imaging

Spot polishing machines for rapid manufacture of standard and high accuracy spheres place new requirements on interferometer systems. The spot polishing method can create small ripple in the surface while shaping the overall form. Accurate positioning of the polishing spot is required to correct the surface errors to bring the surface into specification. To guide the spot polishers image distortion, resolution, and pixel scaling (calibration) are important These requirements primarily drive the imaging system of the interferometer. Continuous zoom system do not meet these requirements.

Modern Imaging Systems

Modern interferometers have discrete or fixed magnification imaging to improve resolution, and minimize distortion and ray tracing errors. All the interferometer optics are exposed to coherent laser light which highlights surface defects. Therefore the optics must be high quality to supress bulls eye artifacts (stray fringes) from scratches, pits, dust and reflections. These hight quality optics increase the system cost.

Interferometer Image Resolution

Increased resolution is required to measure mid-spatial frequency surface features. These features can be defined as the residuals present after the removal of 36 Zernike polynomial terms (see REVEAL analysis screen below, the image on the right are the residual mid-spatial frequencies). Mid-spatial frequencies in an optical surface scatters light degrading the image or lowers directed energy concentration. Therefore they must be measured and corrected.

Mid-spatial frequencies are measured with a high resolution imaging system. Typically greater than a megapixel camera is required. The resolution is limited by either the optical design or the camera resolution. If the camera limits then the smallest feature measurable is approximated by 80% of Nyquist frequency
(1-line/mm:2 Pixels), or ~400 lines/aperture for a megapixel camera. At 50 mm field of view, approximately 125 µm feature can be imaged. Continuous zoom interferometers are limited to <100 lines/aperture.

Interferometer Image Distortion

Image distortion maps a surface feature in the wrong position, and the polisher will move to the wrong position. In the best systems the camera limits resolution. As noted 400 lines/aperture is the practical limit of resolution in a megapixel camera, so distortion of 1/400 or 0.25% is required. The polishers polishing function might decrease this requirement, but with 0.25% the interferometer will not be the limiter. For higher resolution cameras the 80% Nyquist again drives distortion… more pixels better distortion requirements, yet practically the polishing function (the shape of the polishing spot) is the limiter. Continuous zoom systems can exhibit up to 2% distortion – 10X higher than modern interferometers.

Interferometer Ray Tracing Errors

When the test part deviates from a sphere many fringes are seen. These fringes indicate high slopes between the reference and test wavefronts. When high slopes occur the test and reference wavefronts traverse different paths through the imaging optics. These divergent paths create wavefront errors in an uncorrected interferometer system. This error can be measured by acquiring data with a null interference cavity, saving the data and then acquiring data with the maximum number of tilt fringes that can be measured and subtracting the two results. The residual error will primarily be due to ray tracing errors and is seen as coma and astigmatism, and sometime spherical aberration. In the old continuous zoom systems thes

e errors can be as large as a wave of error. Even for the small amount of slopes they can measure.

To speed the convergence of the polishing correction process minimizing these ray tracing errors are required. Only the highest quality systems are corrected for ray-trace errors.

Summary

For spot polishing of spherical and flat components a low distortion, high resolution interferometer with low ray trace errors is desired.

Next Post: Next we discuss special applications, starting with Harsh environments

February 1, 2016April 24, 2020

Optical System Alignment and Wavefront Measurement – Buyers Guide Chapter 4

In this blog the alignment of optical systems with a Fizeau interferometer is discussed.

The goal of a system wavefront test is alignment and confirmation of system performance. The measurement of optical system wavefront often requires a custom interferometer. When a fully reflective system is measured a standard HeNe laser Fizeau is sufficient as the wavelength does not matter. For refractive systems the wavelength often must match the optical system design, and optical system wavelengths vary from 10.6 um to 193 nm. Thus these systems are often “custom” except for a few wavelengths that are more common. For this discussion the wavelength is assumed to be matched to the system.

Zernike polynomials are often used to define system wavefront errors during alignment

Null Test

If a null, adjust until near-zero error is the goal then a standard continuous zoom system can be sufficient. At null ray trace errors are minimized and wavefront imaging distortion error minimal. Further mid-spatial frequency errors are not critical when measuring system alignment. Some of these measurements are made with a null corrector lens that matches the system under test wavefront with the interferometer expected wavefront, either spherical or plano.

Non-Null Testing

Subsystem testing can produce non-null wavefronts in the final alignment. For non-null system an interferometer with low ray-trace errors is important. With high fringe density, or high slopes, ray trace errors grow. Ray-trace errors are developed when the test and reference wavefront traverse diverging paths to the camera and are seen primarily as coma and astigmatism, with sometimes spherical errors. If the final “aligned” condition is at 10 waves of spherical aberration then unless the interferometer is well corrected for ray-tracing errors the data will exhibit errors in final alignment.

Precision alignment is important for optimal optical system performance, especially with more complex optical paths.

Small systems

A bench top system test is similar to measuring an optical component and standard phase shifting data acquisition is sufficient.

Real Time Adjustment

Recently the introduction of widely available simultaneous data acquisition interferometers have enabled near real time phase. So alignments can be adjusted continuously for more rapid convergence on alignment.

Large Systems

For large systems, typically telescopes, vibration and turbulence become an issue. If an issue then only a simultaneous phase measuring system will be able to acquire data.

Summary

In most cases a standard interferometer with near matching wavelength is sufficient to test optical system wavefront. Where large or non-nulled cavities are involved a high performance interferometer with low ray-trace errors and/or simultaneous phase measurement need to be used.

Next Post: Small tool polishing applications

January 29, 2016March 13, 2018

Lap Polished Flats, Spheres and Prismatic Components – Buyers Guide Chapter 3

In this blog the measurement of optics with a Fizeau interferometer that have been lap polished is discussed.

What interferometer is needed to produce good parts? Each manufacturing process requires a specific measurand, the quantity to be measured, to provide the feedback necessary to control the process and produce good parts. In the following posts several applications will be discussed with optional systems highlighted.

Random, Near of Full Sized Tool Polishing

The historic method to manufacture optics has been random polishing on a spindle polisher. The procedure of rough forming the surface

shape, grinding to near polish and then lap polishing has been used for hundred of years. The beauty of lap polishing is the random nature, averaging over large areas of the sphere, which self corrects, and lead to high quality surfaces. Further the mid-spatial frequency ripples, the residual surface features remaining after the removal of 36-Zernike polynomials, tends to be suppressed due to averaging. There are limits and caveats as always, yet in general these are reasonable assumptions. Thus the measurand is simply the shape of the surface as defined by 36 Zernike polynomial coefficients.

The Old Zygo® Mark II Optics Sufficient

Since the meaurand is simply low spatial frequency shape, in this application, a continuous zoom imaging interferometer, with the inclusion of phase measurement is sufficient. This is why the Mark II architecture as been useful for over 35 years, it was sufficient for nearly all optics produced until this century. The low spatial resolution of the imaging system (no matter the camera resolution), and inherent image distortion of the zoom lens up to ~2%, and slope induced errors have little effect on measurement uncertainty of flats and spheres when measured at a null fringe condition.

Vibration Tolerant Data Acquisition Important

More important than the optical system for this application is the data acquisition and analysis software. This starts with vibration tolerant phase data acquisition as found in modern systems to report phase data without the influence of the production environment vibration. (We plan to discuss the history and development of vibration tolerant PSI in a future blog.) Further the software must be compatible with standard industry standards including ISO and data formats (.dat formats), and be easy to use.

Upgrading an Old Interferometer Is a Good Option

To stay current and meet the the requirements of lap polished optics there are two choices: Buying new or upgrading. The first option is purchasing a newly constructed system with classic optical components that has a new data acquisition system. The second is simply upgrading a classic system to a modern data acquisition system (with vibration tolerant algorithms). The performance of each will be equivalent, with the upgrade being much less expensive.

Summary

Lap polished Flats, Spheres and Prisms in a normal production environment are sufficiently measured with a continuous zoom system, where the value choice is often a system upgrade.

In the next post we’ll explore what is an appropriate interferometer for transmitted wavefront measurement.

January 22, 2016January 11, 2021

Brief History of the Laser Fizeau Interferometer – Buyers Guide Chapter 2

Click here to read an detailed history

Hippolyte Fizeau, Inventory of the Fizeau Interferometer

In this blog a brief historical outline of the Fizeau interferometer is presented.

Understanding the history of the commercial laser Fizeau interferometer helps to understand the choices available in today’s market. Some systems available today are remnants of historic designs.

Circa 1850: Fizeau Interferometer Invented

Hippolyte Fizeau invented this interferometer configuration for an 1851 experiment that at the time supported the either-drag theory, later disproven by Michelson, leading the way to Einstein’s theory of relativity

1960’s: Lasers

Laser Invented paving way for the laser Fizeau, an unequal path interferometer

1970’s: The architecture is established

The first commercial laser Fizeau interferometer, named for George Hunter the designer

Zygo® invents basic system architecture with sensor (mainframe) and reference (transmission sphere/flat) – the GH Interferometer in 1974.
Zygo® employs twin-spot alignment, with continuous zoom/rotating ground glass imaging design to accommodate low resolution (Vidicon camera) and off the shelf zoom lens (Mark II, in 1978).
Fringe following data acquisition introduced to replace visual fringe evaluation.
Bell Labs invents phase measuring interferometry on a 32X32 array data acquisition using a Vidicon camera, and PDP 8 rack mounted computer.

1980’s: Data acquisition improvements

Digital detectors (up to 256X256 by the late 1980’s), CCD/CID, and workstation computers introduced.
Carrier fringe and four camera simultaneous phase measurement invented (SPMI) for vibration insensitive data acquisition.

1990’s: Software advances

The First Phase Measuring Interferometer at Bell Labs

Enhanced graphics and additional results with faster processing in lower cost personal computers, primarily driven by Wyko and followed by Zygo®
CCD’s with 512×512 pixels introduced – no changes to the ground glass-continuous zoom historic imaging design

2000’s: Data Acquisition and illumination Improved

4D Technologies and ESDI successfully commercialize SPMI
Asphere interferometer introduced: Stitching (QED), Fizeau Scanning (Zygo®)
1KX1K custom imaging driven by deterministic, computer controlled spot polishing
Push to better imaging systems in custom designs
Lower spatial coherence illumination (ring) introduced to improve measurement accuracy

2010’s: MegaPixels + Low Ray Trace Errors + Improved imaging

First newly designed interferometer optical systems that break the ground glass-continuous zoom historic design for high-resolution, low distortion imaging plus minimized ray-trace errors for improved accuracy with steeply sloped wavefronts from mild asphere optics
Sub-nyquist (ESDI) asphere interferometer introduced

2020 and Beyond: Light Sources and Software

Lasers have dominated since the 1960’, but their limitations are catching up with them. Vertex back reflection fringes limit measurement accuracy, spurious fringe mask mid-spatial frequencies, and lasers are unable to measure domes, plates, prisms due to back surface reflections.

To overcome these limitations low coherent sources have been introduced. Delay line white light sources minimize the back reflections and spurious fringe problem but are nearly impossible to align, like a standard white light source.

ÄPRE’s Spectrally Controlled Interferometry (SCI) retains the ease of use of a laser with a long coherence mode and then switches to short coherence (white light) mode at camera frame rates. SCI can also measure the cavity distance enabling the measurement of radius of curvature, without the external radius rail, at higher accuracy. SCI looks like the source of the future.

Confused fringes with laser source (left), clean fringes with SCI (right)

SCI source Spectrum (left) produces Interference fringes (right)

Software

The control of the entire measurement process will become possible with every interferometer using the same measurement setup via centralized control without variation user to user. Software will guide the user as to whether a part passes or fails, and databases will track parts through manufacture and data will be reported consistently, all enabling better process control and thus improved parts.

Summary

The Fizeau interferometer has a long history and promising future. Contact ÄPRE to discuss your interferometery needs to apply the best source + interferometer to your application.

In the next post we’ll explore what is an appropriate interferometer for lap polished flats, spheres and prismatic components.

January 21, 2016March 13, 2018

Fizeau Interferometer Buyers Guide – Chapter 1

The many laser Fizeau interferometer choices make selection confusing.

You don’t want an laser Fizeau interferometer. You just want optics that meet specification, and your Fizeau interferometer helps you do just that. Yet choosing the right interferometer can be confusing. Just consider the choices:

Data Acquisition

PSI, IPMI, or Carrier Fringe, or wavelength tuning, vibration insensitive, vibration tolerant, multi-surface, scanning Fizeau, stitching…

Illumination

high-coherence, low-coherence or partial coherence (ring)

Wavelength

633nm, 1.06um, 3.39um, 1550nm, 10.6um, 650nm, and many others.

Imaging

zoom, discrete, and fixed magnification, plus ground glass or coherent

Detectors

256K, Mega or multi-mega pixel detectors, and then their is CCD or CMOS

System Configurations

Common path, off-axis, high-slope, steep surface, mid-spatial frequencies

Software Analysis

Zernike, slope, ISO, masking, frequency filters, box filters, and a plethora of others

Applications

wavefront, surface, radius of curvature, homogeneity, wedge, corner cubes and …

The combinations are hard to keep track of let alone configure to your specific requirements and budget. So over the next few weeks we will be running a series of blogs to offer some guidance and insight regarding what is important depending on your application.

In the next post we’ll set the stage with a brief history of optical test interferometry.

October 19, 2015January 4, 2018

SPIE: Optifab Rochester NY

It was great making new acquaintances and meeting old friends in Rochester. Optifab continues to be a premier event for optical manufacturers and equipment makers alike. Even the autumn weather did not disappoint.

The REVEAL v1.3 reception was excellent! The new features and capabilities struck a positive cord regarding ease of use and functionality. Especially of interest is REVEAL’s unique reporting function. The ability to create a custom report template for each customer, and not just print out a screen dump, makes shipping documentation easier and meaningful at the same time.

Upgrades to classic interferometers continues to be a hot item. Several times old friends stopped by to say hello, to learn that a useless interferometer they had sitting in a corner could be easily resurrected, with improved performance, and at a low cost.

We can feel the momentum building as REVEAL powers new OEM interferometer applications and the easy upgrade of classic interferometer. Let us know how we can help with your optical test interferometry needs.

February 26, 2015January 4, 2018

Photonics West – REVEAL & 12″ Fizeau

We had an exciting and active Photonics West this year.

Co-exhibiting with Davidson Optronics we demonstrated Davidson’s new 12″ interferometer, designed by Äpre Instruments with Davidson, for Davidson’s manufacture and sales. ÄPRE performed all the sensor’s optical, optical mechanical design, system electronics, firmware and software, which of course runs on REVEAL™. This was an exciting project and a good example of our capabilities. Designed in 13 months, it was a pleasure working with Davidson on this project.

Our OEM REVEAL™ software was a big hit! Both as a basis for interferometer upgrades as well as OEM applications.

We also demonstrated a $44,500 optical profiler running on REVEAL™. It can measure large, >150 mm diameter surfaces, or small optics depending on the configuration.

We look forward to meeting you at our next tradeshow.