Standard and high-resolution Fizeau interferometers

Hardware

Fizeau interferometers are often used to exactly measure the surface characteristics of optics such as lenses or mirrors. The development team of Äpre Instruments

The development team at Äpre Instruments can rely on decades of experience in the interferometer industry and has put all the knowledge gained into the development of its own modern Fizeau interferometers and light sources.
In the devices of the S and Ä series the optical bench is completely separated from the electronics board. State-of-the-art digital cameras are used both for aligning the optical axis and for measuring the surface. The image resolution can be configured up to 9 megapixels. Communication with the PC takes place via USB3.

Software Reveal

Not only the hardware but also the software comes completely from Äpre Instruments. In digital interferometry, the software for controlling and evaluating the data is at least as important and decisive as the hardware. The software developers at Äpre Instruments have therefore worked for years to write software that is as user-friendly as possible for use in optics manufacturing and at the same time extremely powerful.
View software

Spectral Controlled Interferometry

All standard and high-resolution Fizeau interferometers from Äpre Instruments are equipped with a frequency-stabilized SLM 633 nm HeNe laser. The measurement technique can be carried out using either traditional phase shift, vibration-tolerant phase shift or the vibration-insensitive carrier fringe method. In addition, each interferometer can be connected to Äpre Instruments’ own specially developed light source, which can be used to measure different surfaces separately using the so-called SCI technology (Spectrally Controlled Interferometry).
View SCI light source

For more in-depth reading on the subject, we recommend this article.

Fizeau interferometers for surface and wavefront metrology

S-Series 1MP

S50|1MPS100|1MPS150|1MP
System Overview
Output Diameter51 mm (2 inch)102 mm (4 inch)153 mm (6 inch)
Optical Centerline108 mm (4.25 inch)108 mm (4.25 inch)133 mm (5.24 mm)
Focus Range (position readout)±0.5 meters±2 meters±4.5 meters
Interferometer size (L x W x H)63 x 29 x 18 cm70 x 32 x 25 cm90.2 x 40.8 x 23.9 cm
Weight25 kg (55 lbs)33 kg (73 lbs)50 kg (110 lbs)
Measurement TechniquesFast/Sensitive Spectral Synchronous, Vibration-Tolerant PSI
Plus Vibration-Insensitive Carrier Fringe
Alignment System2-spot with reticle with 2° capture range
Light SourceSCI SpectrÄ 2.0, HeNe Laser, and ÄTLas Wavelength Shifting
Laser Frequency Stability<0.0001 nm
Temporal coherence LengthSCI SpectrÄ 2.0 ≤2 meters, HeNe Laser >100 meters, ÄTLas ≤3 meters
Output PolarizationCircular (Linear optional for birefringent part measurement)
Camera Resolution1022 x 1022
Camera frame rate (max)90 Hz (25 Hz with SCI source)
Shutter Speed – shortest9 µs
Camera digitization8 bit
Computer & SoftwareHigh-Performance PC, Windows11, 64-bit OS & REVEAL Software
Mounting ConfigurationsHorizontal or Vertical
Performance
Image Resolution (Detector Limited)100 µm (10 l/mm)200 µm (5 l/mm)300 µm (3.3l/mm)
Image Distortion<0.1%
Fringe Resolution>300 fr/aperture
Retrace Error3 @ 256 fringes< λ/15
RMS Simple Repeatability1<0.6 nm RMS 2σ
RMS Wavefront Repeatability2<0.6 nm RMS 2σ
Measurable Part Reflectivity0.1%to 40% direct and >41% with attenuation filter or coatings
Environment
Temperature15º C to 30º C
∆T/∆t<1.0º C/15 min
Humidity5 to 95% relative, non-condensing
Vibration IsolationIsolation System recommended for VTPSI
1) RMS Simple Repeatability Test: The RMS for 36 sequential measurements with each measurement the average of 16 measurements each of a short <2 mm plano cavity
2) RMS Wavefront Repeatability Test: Measure 36 sequential Measurements (M1, M2,...M30) each consisting of 16 averages. Then average all 36 measurements create a synthetic reference, "Ref", RMS wavefront repeatability equals the 2X the standard deviation of all 30 Ref - Mn results.
3) Retrace Error is defined as the PV residual error between a nulled measurement (the reference), subtracted from a measurement with 500 fringes of tilt, and expressed by the first 36 Zernike polynomials
4) λ/20 optionally available
5) Resolution is detector limited at 800 lines/aperture
Specifications subject to change without notice


S-Series 4MP

S50|4MPS100|4MPS150|4MPS300 | 4MP
System Overview
Interferometer TypeFizeau Configuration
Output Diameter51 mm (2 inch)102 mm (4 inch)153 mm (6 inch)306 mm (12 inch)6
Optical Centerline108 mm (4.25 inch)108 mm (4.25 inch)133 mm (5.24 mm)Specify
Focus Range ±0.5 meters
±2 meters
(encoded)
±4.5 meters
(encoded)
±2 meters
(position readout)
Interferometer size (L x W x H)63 x 29 x 18 cm70 x 32 x 25 cm90.2 x 40.8 x 23.9 cm76 x 40 x 50 cm
Weight25 kg (55 lbs)33 kg (73 lbs)50 kg (110 lbs)TBD
Phase Measurement TechniquesFast/Sensitive Spectral Synchronous, Vibration-Tolerant PSI
Plus Vibration-Insensitive Carrier Fringe
Fast/Sensitive Synchronous, Vibration-Tolerant PSI
Plus Vibration-Insensitive Carrier Fringe
Alignment System2-spot with reticle with 2° capture range
Three optional light sourcesSCI SpectrÄ 2.0, HeNe Laser, and ÄTLas Wavelength Shifting
HeNe Laser Frequency Stability<0.0001 nm
Temporal coherence LengthSCI SpectrÄ 2.0 ≤2 meters, HeNe Laser >100 meters, ÄTLas ≤3 meters
Output PolarizationCircular (other options available)Circular or Linear, for birefringent materials
Camera Resolution2040 x 2048 pixel2044 x 2044
Camera frame rate (max)180 Hz @ 2040 X 2048 pixels≤180 Hz (source dependent)
Shutter Speed – shortest9 µs
Camera digitization8 bit12 bit
Computer & SoftwareHigh-Performance PC, Windows 10 64-bit OS & REVEAL Software
Mounting ConfigurationsHorizontal or VerticalHorizontal or Vertical or Adjustable
AccessoriesOptical Accessories and Mounts Availablen/a
Performance
Image Resolution5
63 µm
16 l/mm
5
125 µm
8 l/mm
5
188 µm
5.3 l/mm
230 µm (4.2 l/mm)
Image Distortion<0.06%
Fringe Resolution≥600 fr/aperture>500 fr/aperture
Retrace Error3 @ 511 fringes≤ λ/154
RMS Simple Repeatability1<0.6 nm RMS 2σ
RMS Wavefront Repeatability2<0.6 nm RMS 2σ
Measurable Part Reflectivity0.1%to 40% direct and >41% with attenuation filter or coatings0.5% to 100% Specify
Environment
Temperature15º C to 30º C
∆T/∆t<1.0º C/15 min
Humidity5 to 95% relative, non-condensing
Vibration IsolationIsolation System recommended for VTPSIIsolation System recommended for PSI
1) RMS Simple Repeatability Test: The RMS for 36 sequential measurements with each measurement the average of 16 measurements each of a short <2 mm plano cavity
2) RMS Wavefront Repeatability Test: Measure 36 sequential Measurements (M1, M2,...M30) each consisting of 16 averages. Then average all 36 measurements create a synthetic reference, "Ref", RMS wavefront repeatability equals the 2X the standard deviation of all 30 Ref - Mn results.
3) Retrace Error is defined as the PV residual error between a nulled measurement (the reference), subtracted from a measurement with 500 fringes of tilt, and expressed by the first 36 Zernike polynomials
4) λ/20 optionally available
5) Resolution is detector limited at 800 lines/aperture
6) Up to 310mm is available on special request
Specifications subject to change without notice


Ä-Series 4MP

Ä50|4MPÄ100|4MPÄ150|4MP
System Overview
Interferometer TypeFizeau Configuration
FunctionSurface, wavefront, TTV, and angle metrology
Output Diameter51 mm (2 inch)102 mm (4 inch)153 mm (6 inch)
Optical Centerline108 mm (4.25)108 mm (4.25 inch)133 mm (5.24 mm)
Focus Range (encoded)±0.5 meters±2.0 meters±4.5 meters
Interferometer size (L x W x H)63 x 29 x 18 cm70 x 32 x 26 cm90.2 x 40.8 x 23.9 cm
Weight25 kg (55 lbs)33 kg (73 lbs)50 kg (110 lbs)
Phase Measurement TechniquesSpectral Synchronized, Vibration Tolerant & Vibration Insensitive Carrier Fringe
Alignment System2-spot with reticle with 2° capture range
Three optional light sourcesLaser, SpectrÄ 2.0 and Wavelength Shifting
HeNe Laser Frequency Stability<0.0001 nm
Temporal coherence LengthHeNe Laser >100 meters, SpectrÄ 2.0 > 2 meter
STAR: Spatial Coherence ControlReduces coherent noise when averaging
Add SpectrÄ for true White Light Fizeau Performance6
Output PolarizationCircular (Other options available)
Camera Resolution2040 x 2040 pixel
Camera frame rate (max)180 Hz
Shutter Speed – shortest9 µs
Camera digitization8 bit
Computer & SoftwareHigh-Performance PC, Windows 10 64-bit OS & REVEAL Software
Mounting ConfigurationsHorizontal or Vertical
AccessoriesOptical Accessories and Mounts Available
Performance
Image Resolution563 μm
16 l/mm
85 µm
12 l/mm
125 µm
8 l/mm
Image Distortion<0.06%
Fringe Resolution≥600 fr/aperture
Retrace Error3 @ 512 fringes≤ λ/154
RMS Simple Repeatability1<0.6 nm RMS 1σ – with NO averaging
RMS Wavefront Repeatability2<0.6 nm RMS 1σ – with NO averaging
Measurable Part Reflectivity0.1%to 40% direct and >41% with attenuation filter or coatings
Environment
Temperature15º C to 30º C
∆T/∆t<1.0º C/15 min
Humidity5 to 95% relative, non-condensing
Vibration IsolationIsolation System recommended for VTPSI

1) RMS Simple Repeatability is defined as 1X the standard deviation of the RMS for 36 sequential measurements (0 averages ) of a short, 1 mm plano cavity
2) RMS Wavefront Repeatability is defined as the mean RMS difference between a synthetic reference (defined as the a verage of a ll 36 sequential
measurements) and each measurement plus 1X the standard deviation
3) Retrace Error is defined as the PV residual error between a nulled measurement (the reference), subtracted from a measurement with 500 fringes of tilt, and
expressed by the first 36 Zernike polynomials
4) λ/20 optionally available
5) Resolution is detector limited at 800 lines/aperture
6) STAR is Spatial and Temporal Artiface Reduction for unique White Light Fizeau performance, with laser alignment ease
Specifications subject to change without notice


Ä-Series 9MP

Ä100|9MPÄ150|9MP
System Overview
Interferometer TypeFizeau Configuration
FunctionSurface, wavefront, TTV, and angle metrology
Output Diameter102 mm (4 inch)153 mm (6 inch)
Optical Centerline108 mm (4.25 inch)133 mm (5.24 mm)
Focus Range (encoded)±2.0 meters±4.5 meters
Interferometer size (L x W x H)70 x 32 x 26 cm90.2 x 40.8 x 23.9 cm
Weight33 kg (73 lbs)50 kg (110 lbs)
Phase Measurement TechniquesFast/Sensitive Spectral Synchronous, Vibration-Tolerant PSI
Plus Vibration-Insensitive Carrier Fringe
Alignment System2-spot with reticle with 2° capture range
Three optional light sourcesSCI SpectrÄ 2.0, HeNe Laser, and ÄTLas Wavelength Shifting
HeNe Laser Frequency Stability<0.0001 nm
Temporal coherence LengthSCI SpectrÄ 2.0 ≤2 meters, HeNe Laser >100 meters, ÄTLas ≤3 meters
STAR: Spatial Coherence ControlReduced coherent noise when averaging
Add SpectrÄ for for low temporal & spatial coherence performance6
Output PolarizationCircular (Linear optional for birefringent part measurement)
Camera Resolution3000 x 3000 pixel
Camera frame rate (max)90 Hz
Shutter Speed – shortest9 µs
Camera digitization8 bit
Computer & SoftwareHigh-Performance PC, Windows 10 64-bit OS & REVEAL Software
Mounting ConfigurationsHorizontal or Vertical
AccessoriesOptical Accessories and Mounts Available
Performance
Image Resolution585 µm
12 l/mm
125 µm
8 l/mm
Image Distortion<0.06%
Fringe Resolution≥900 fr/aperture
Retrace Error3 @ 512 fringes≤ λ/154
RMS Simple Repeatability1<0.6 nm RMS 2σ
RMS Wavefront Repeatability2<0.6 nm RMS 2σ
Measurable Part Reflectivity0.1%to 40% direct and >41% with attenuation filter or coatings
Environment
Temperature15º C to 30º C
∆T/∆t<1.0º C/15 min
Humidity5 to 95% relative, non-condensing
Vibration IsolationIsolation System recommended

1) RMS Simple Repeatability Test: The RMS for 36 sequential measurements with each measurement the average of 16 measurements each of a short <2 mm plano cavity
2) RMS Wavefront Repeatability Test: Measure 36 sequential Measurements (M1, M2,...M30) each consisting of 16 averages. Then average all 36 measurements create a synthetic reference, "Ref", RMS wavefront repeatability equals the 2X the standard deviation of all 30 Ref - Mn results.
3) Retrace Error is defined as the PV residual error between a nulled measurement (the reference), subtracted from a measurement with defined fringes of tilt, and expressed by the first 36 Zernike polynomials
4) λ/20 optionally available
5) Resolution is detector limited at 80% of Nyquist or 1200 lines/aperture for a 9MP sensor.
6) Spatial and Temporal Artifact Reduction for unique low noise performance when combined with SCI SpectrÄ source, with laser alignment ease
7) Design performance as modeled in Zemax wtih 2 meter cavity length
Specifications subject to change without notice