Characterisation, Measurement & Analysis
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Applications

  • Improved Power Measurement Accuracy with Thermopile Laser Power Sensors

    Thermopile laser power detectors allow greater accuracy laser power measurement tools across a wide wavelength range.

    B05-MC-PCB-mounted-sensor

     

    Figure 4 greenTEG B05-MC power detector

    In order to achieve optimal laser power measurement, the influence of the thermal environment has to be considered. There are 2 basic sources of laser power variation that need to be considered.: (i) temperature and (ii) the background. greenTEG® power detectors can mitigate against both of these sources of variation to allow faster, more accurate power measurement.

     

    (i) Temperature error

    Cause

    Typically, the power sensor sensitivity is only valid for the temperature at which the calibration was made. The sensitivity varies linearly with the sensor temperature. The magnitude of this error does not depend on the measured laser power.

    Correction

    The temperature error can be corrected by multiplying the measurement value by a temperature dependent correction factor.

    greenTEG Solution

    The digital sensor head has a built-in temperature sensor and microprocessor that automatically applies a temperature correction. The output signal is a fully compensated digital signal.

    (ii) Background error

    Cause

    Background errors occur if the sensor temperature differs from the surrounding air temperature. This type of error is most significant when measuring low laser powers.

    Correction

    The background error can be minimized by keeping the sensor at the same temperature as the air and avoiding air flows across the sensor. It can also be corrected by subtracting the background signal recorded at zero laser power, or by using a second sensor (blocked from the laser light) that only records the background signal.

    greenTEG Solution

    greenTEG‘s double sensors (e.g. the B05-MC in Figure 4) reduce background errors by up to two orders of magnitude by direct background subtraction using a dark sensor.

    Real life measurement

    In most real life measurement set ups one will encounter both effects simultaneously. The dominant error depends on your set up, laser power and sensor type. As a rule of thumb one can say the following:

    • Background errors are negligible (<1%) for laser powers above 10W.
    • The temperature error affects measurements at all laser powers, but is more likely to be important at laser powers above 10W, where bigger temperature deviations can be expected.

    Based in Zurich, greenTEG AG is a new company exploiting the latest thermoelectric technology developed at the Swiss Federal Institute of Technology (ETH Zurich). This technology is used to develop, manufacture and market detectors for use in Heat Flux sensing, Laser Power Monitoring, and Energy Harvesting applications

  • Characterising the Optical Properties of Planar Waveguides, Optical Chips and Planar Light Circuits

    Overview

    Planar optical waveguide technologies are the key elements in the modern, high speed optical network. Recent broad deployment of optical and hybrid optoelectronic chips and planar light circuits (PLCs) has been driven by the cost, size and operational benefits that these architectures offer.

    From a measurement perspective, planar optical waveguide architectures offer several unique challenges. Even the highest quality Photonic chips are far more lossy per unit length than optical fibre due to higher absorption and scattering coefficients. Planar systems are also often much more polarisation dependent, and planar systems are often multi-path and have strong wavelength dependencies (e.g. modulators, arrayed waveguide gratings). Nonetheless, rapid, accurate and thorough characterisation of planar waveguides is key to functionality and operability.

    Optical vector analysis offers several distinct measurement advantages that make it particularly well suited for characterisation and analysis of planar waveguides and circuits.

    High Speed Parametric Measurement

    For most applications, optical waveguides must be characterized in terms of standard parameters required as input into network designs and maps. Those parameters include loss (both insertion, IL, and return, RL), group delay and/or chromatic dispersion (GD, CD), and polarisation dependencies like polarization dependent loss (PDL) and differential group delay or polarisation mode dispersion (DGD, PMD). Note: For discrete components, like planar waveguide chips, DGD=PMD. For most modern networking applications support multiple operational wavelengths and these quantities must therefore be measured by both designer and manufacturer over multiple input wavelengths. This is commonly achieved by employing a tunable laser source (TLS) performing multiple, time consuming measurements.

    The OVA (Optical Vector Analyser) from LUNA INC., provides the industry’s only single-scan, single connection, high-speed turn-key measurement solution with near instant access to all parametric quantities of interest such as IL, RL, GD, CD, PMD, PDL, etc. Figure 1 below shows an OVA measurement of the IL, PDL, GD and PMD of an interleaving device fabricated in a PLC.

    Figure 1

    Figure 1. Insertion loss (IL) and polarisation mode dispersion (PMD) of three channels of an arrayed waveguide grating in a planar optical chip. This data was taken with 2.5 pm wavelength steps. Using OVA, full band characterisation is completed in about three seconds.

    High speed measurement is essential to PLC development and manufacturing as PLCs often require alignment to optical fiber. This step can be greatly simplified using the high speed nature of OVA as both alignment and final test can be performed simultaneously at a single test station.

    Time Domain Mapping and Measurement of Distributed Loss

    The complex measurement of the OVA allows the user to not only perform high speed spectral analysis, but also, by use of the Fourier transform, allows the user to image an optical waveguide in the time-domain.

    By virtue of its operating principle; measurements of frequency-domain amplitude and phase OVA allows the user to interrogate optical waveguides in both the frequency- and time-domains. That is, the frequency domain data for a given waveguide can be Fourier transformed into a high-resolution time domain picture of that components spatial response.

    Figure 2

    Figure 2. Time domain response in reflection of a silica-on-silicon waveguide measured using an OVA

    Figure 3 below displays the time domain impulse response of a highly birefringent PLC waveguide in transmission. The multiple impulses are due to light propagating back and forth between the waveguide facets (the Fabry-Perot effect).

    Figure 3a

    Figure 3. (a) Graphical depiction of light propagating in a planar waveguide showing the primary and secondary (1st echo) transmission

    Figure 3b

    Figure 3. (b) Time domain impulse response of a highly birefringent optical waveguide in transmission. The TE and TM response are clearly visible in the splitting of the transmission peaks as are the multiple round trip “echoes” cause by light propagating multiple times in the waveguide area.

    Polarisation Effects

    Due to the geometry of planar devices, they typical suffer from stronger polarisation dependence than the cylindrical geometry encountered in many other fiber systems. As polarisation effects such as PMD can be the limiting factor in high speed optical data transmission.

    OVA is unique in that it is capable of characterising polarisation effects such as PDL and PMD by scanning a tunable laser only once. This is achieved by conditioning the optical signal in the fibre before it propagates through the waveguide under test. The single scan nature of the technique leads to greatly enhanced measurement speeds and higher levels of accuracy and repeatability.

    A result of this method of device characterisation is that it relaxes the precise alignment requirements often associated with testing planar waveguides.

    Figure 4 below highlights several measurement results showing various polarisation inputs.

    Figure 4

    Figure 4. A screen capture showing TE (Red) and TM (green) transmission through a polarizing waveguide. The blue curve represents the wavelength dependant transmission of a mixture of the TE and TM states caused by errors in the launch condition. Using optical vector analysis, this level of polarisation analysis can be extracted instantly from measured data requiring no prior alignment.

    Summary

    Planar optical waveguide technologies are the key elements in the modern, high speed optical network but present unique challenges from a measurement perspective. Even the highest quality Photonic chips are far more lossy per unit length than optical fibre due to higher absorption and scattering coefficients; they are often substantially more polarisation dependent, and frequently have multi-path and strong wavelength dependencies (e.g. modulators, arrayed waveguide gratings). Optical Vector Analysis with the LUNA OVA system offers several distinct measurement advantages, making it particularly well suited for the characterisation and analysis of planar waveguides and circuits.

    Click here for more information on LUNA’s OVA

  • Latest applications of gRAY detectors

    greenTEG_col_web5The new greenTEG laser power detector family enables fast and precise laser power measurements across a wide range of laser powers from 100 μW to 50W. gRAY® laser power detectors are available as housed, mounted or compact bare die components and are well suited for integration into power meters, laser sources and systems where space is limited.

    The two key benefits of gRAY® detector technology are the sensitivity to all wavelengths from the deep ultra-violet (190nm) to the mid infrared (15µm) and fast response times as low as 200ms. These features have led to gRAY® power detectors replacing photodiodes and traditional thermopiles for laser power measurement in a number of different case studies highlighted here.

    Medical Laser Systems:

    Case_1Case 1: Process stability is crucial for precise tissue cutting and laser ablation in medical surgeries. Throughout the laser process, the CW CO2 laser power level of 60 W needs to be measured periodically for 1-2 s before a surgery. With a beam-diameter of 6-8 mm the power density is well below the threshold value of 1.5 kW/cm2 for gRAY detectors. To save both cost and space, the customer uses a gRAY BC50-MC integrated into the beam path behind a tiltable mirror, (as shown right), which is flipped during the short measurement periods between surgeries to allow the laser beam hit the detector for laser power measurment. After measurement, the mirror is flipped back to use the full laser power for the surgery procedure.

     

    Case_3Case 2: Due to EU regulations, every medical laser system must be equipped with an internal,  redundant power measurement unit. The gRAY B01-SMC was integrated into a system using a 3 μm wavelength laser with 10W (CW) average power. In order to save space, the B01-SMC detector is soldered directly onto the electronics board. This makes the whole unit very compact and ensures good thermal and electric coupling. To allow continuous monitoring of the laser power, the board is mounted behind a (90:10) beam splitter so that about 1W is incident on the detector. The 90% of the laser beam is coupled into an optical fibre and used for micro surgical tissue cutting.

    Industrial Laser Systems:

    Case_2Case 3: Many laser marking applications have high precision requirements, for example the manufacture of decorative elements, such as logos, on consumer electronic smartphones. Continuous power monitoring of a 5 W (CW) laser systems with wavelengths 1064 nm or 532 nm is typically required. Since space is limited, the gRAY B05-SMC was chosen and integrated into the processing head behind a beam splitter (as shown in the image right). The measured signal is directly fed into a power control loop to stabilize the laser output power to the required level.

     

     


    Case_4Case 4:
    For high power CO2 (CW) cutting laser applications, continuous monitoring of the laser power is frequently required to ensure reproducible production. Power detectors with low rise time ≪1s are desired to minimize power measurement time during production and a compact power meter head also saves space within the laser system. The gRAY C50-HW meets both these criteria and can be  placed behind the laser cavity to measure the light transmitted through the back mirror – typically <50W. This light is only a small fraction of the front output but is directly proportional to the main beam. It can therefore be used for a closed loop control of the laser power. With the thermal, mechanical and electronic integration provided with the housed detector, the assembly of the measurement unit is straightforward.

    Case 5: Another application of gRAY power detectors is within CO2 (CW) laser systems for fusion splicing of optical fibers, where locating the beam position is crucial for high production yield. Space is limited in the system and a customized positioning device was developed for this application. A laser beam of ca. 5 mm diameter is measured at 2 positions inside the system. The laser power is measured for 2 s while the new fibres are loaded to the machine. Using the custom gRAY detector, the measurement unit is much more compact and cost-efficient.

    Power Meters:

    Case 6: To build a compact and highly sensitive power meter, the gRAY B05-SC was selected for integration into a power measurement head. The measurement head is only 30x40x18.5 mm3 in size and can resolve powers down to 10 µW. In order to achieve this high resolution, a second B05-SC detector is placed next to the main detector for compensation of thermal fluctuations in the environment. Using this design much lower rise times could be obtained, which is highly attractive for many industries.

    Case 7: Compact and precise power meters are demanded in industrial environments for preventive maintenance procedures. Compact, high power hand held measurement devices, which can be used for powers up to 100 W, are particularly desired, since commercially available detectors are extremely bulky. To make a compact detector, the gRAY BC50-MC was customized and integrated into its own housing with a temperature-sensor to allow for compensation of the temperature dependence of the power readings.

    Research:

    Case 8: A fast and precise power meter is required to measure the performance of a 1064 nm pulsed laser and the short 200ms rise time of the gRAY C10-HC makes it very suitable for this application. The allows for fast measurements and the coating can withstand laser irradiation of short pulse lasers of pulsewidth 880 fs, repetition rate 3.9 MHz and average power up to 8 W. A voltmeter is used to measure the power sensor signal, which is easily converted into power with the pre-calibrated conversion factor of 1 Watt/Volt.

    A summary of the advantages offered by gRAY detectors is made in the table below:

    Table1_800

    Click here for further information.

    To speak with a Sales/Applications Engineer please call 01582 764334 or click here to email.

  • LASOS dedicated to HeNe Laser production for the modern age

    During the last few years diode lasers have replaced the Helium-Neon laser in many mass applications (e.g., barcode scanner, marking, adjusting, aligning). The global reduction in Helium-Neon laser sales means a great challenge for the few remaining manufacturers. Whereas, on the one hand, niche products require a resourceful mind to ensure the continuity of raw material supplies, on the other hand, many applications in high-precision measuring applications (e.g. interferometers and spectrometers) are inconceivable without the properties of the Helium-Neon laser - properties which solid state lasers cannot achieve. He-Ne lasers meet the constantly growing application needs for mode and frequency stability as well as resistance to magnetic fields. Growing demands on quality in an environment of shrinking volumes, defines a new framework of conditions and challenges for today’s market.

    The He-Ne laser has ceased to be a volume product; it has become a selected component with high application potential to meet specific high customer demands. LASOS is facing up to this challenge and has invested in flexible, modern and highly specialised gas laser production. Absolute focus on the customer is the principle by which LASOS is guided. Customers are highly appreciative when their specific requirements are met, the products are of the high quality they expect and they get good value for their money. You can rely on an efficient and experienced team of development specialists and the extent of in-house manufacturing in Jena, Germany, supports direct access to most different production technologies.

    In addition to the customised range, we supply a large number of standard HeNe types that can also be used as genuine substitutes for existing and obsolete lasers from other well-known manufacturers. With state-of-the art production facilities and German design, engineering and production quality, we can offer a secure modern supply of HeNe laser products and customised OEM solutions for many years to come and for those niche applications where a HeNe is the only solution.

    Download the full article here...

    pdficon LASOS® He-Ne laser series

  • New possibilities for measurements of optical components with PHOTON RT universal scanning spectrophotometer

     

    The new version of PhotonSoft program features advanced capability to conduct group measurements of single and multiple substrates. Such function is of great value when determination of optimum angle of incidence for maximum optical performance is required.

    KB_Batch measurements-eng

    Measurement of a polariser using a sequence of 5 consecutive measurements of transmittance and reflectance. All of them are shown within one screen.

    Example 1. Thin film polariser

    The thin film polarisers are often used to separate polarisation of incoming beam, e.g. laser beam. For appropriate operation of polariser, the light beam shall incident the surface at the Brewster angle (e.g., about 56 degrees to the normal position for BK7 glass). One of the important characteristics of thin-film polariser is the ratio of intensities of the transmitted p-polarised radiation to the transmitted s-polarised radiation - Tp / Ts. The higher the ratio, the better the polariser. In practice, one must set the angle of incidence accurately in order to determine this characteristic by adjusting the angle from about 53 to 59 degrees. Such multiple measurements can be easily carried out unattended even with a 0.1 degree step using the Photon RT spectrophotometer. All measurement results will be instantly saved as Excel files for further analysis. Using the measured data, one can knowingly determine not only the optimum angle of incidence, but also the range of angles and wavelength ranges corresponding to the best performance characteristics of polarizer. To an even greater extent, this great feature will be useful to analyse broadband polarizers.

    Example 2. High-reflectivity mirrors

    This group of optical elements shall demonstrate maximum reflectance within a pre-determined wavelength range. For example, a typical requirement would specify reflectance (Rs, Rp) greater than 99,9% for 975-1175 nm at 45 degrees angle of incidence. For more demanding mirrors, an additional requirement would address not only a particular angle of incidence, but a range of angles, e.g. 40-50 degrees, or 0-45 degrees. Such measurements can be successfully performed with PHOTON RT spectrophotometer and would require just 15-30 minutes to complete. No involvement of optical engineer is required, all measurements are performed unattended, so the user can invest their time in other projects or activities.

    These examples show new possibilities for measurements of optical components with PHOTON RT universal scanning spectrophotometer ensuring accurate, fast and time-efficient results.

    If you have further questions please contact our Metrology team on 01582 764334  or click to email.

     

  • Optical Profiler Basics and some history

    optical-profiler-beam-path

    Optical profilers are interference microscopes, and are used to measure height variations – such as surface roughness – on surfaces with great precision using the wavelength of light as the ruler. Optical interference profiling is a well-established method of obtaining accurate surface measurements.

    Optical profiling uses the wave properties of light to compare the optical path difference between a test surface and a reference surface. Inside an optical interference profiler, a light beam is split, reflecting half the beam from a test material which is passed through the focal plane of a microscope objective and the other half of the split beam is reflected from the reference mirror.

    When the distance from the beam splitter to the reference mirror is the same distance as the beam splitter is from the test surface and the split beams are recombined, constructive and destructive interference occurs in the combined beam wherever the length of the light beams vary. This creates the light and dark bands known as interference fringes.

    Since the reference mirror is of a known flatness – that is, it is as close to perfect flatness as possible – the optical path differences are due to height variances in the test surface.

    This interference beam is focused into a digital camera, which sees the constructive interference areas as lighter, and the destructive interference areas as darker.

    In the interference image (an "interferogram") below, each transition from light to dark represents one-half a wavelength of difference between the reference path and the test path.

    If the wavelength is known, it is possible to calculate height differences across a surface, in fractions of a wave. From these height differences, a surface measurement – a 3D surface map, if you will – is obtained.

    Advantages of Optical Profilers:

    • Optical profiling, as opposed to stylus profiling, is non-contact.
    • Optical profilers measurements are three dimensional (areal): they measure height (the Z-axis) over an area of X and Y lateral dimensions. Stylus profilometers are inherently linear (2 dimensional). A stylus is dragged across the surface, sampling points along a line.
    • Every pixel in the imaging camera is a datum: its optical path difference is calculated relative to each adjacent pixel, by comparing the contrast between them. So, the more pixels in the field of view, the more data you get in each measurement.
    • Stylii wear out, or need to be changed for varying surface conditions. Optical profilers have no stylus, and no expensive 'consumable' parts to replace.
    • Since reliable coupling of focus with interference contrast is essential to repeatable surface metrology, our interference microscopes come with our own athermal objectives: offering better repeatability in variable temperature environments.

    Optical Profilers Obtain Amazing Accuracy with Interferometry

    interferogram-fringes-wavelengthHypothetically, if the wavelength is 500 nanometers, one could estimate the distance of slope over a full wavelength by looking at the light and dark interference bands – known as interference fringes – in an interferogram. Optical profilers calculate these differences much more accurately than is possible by visual methods.

    Looking at the interferogram at right, you might notice that the light and dark bands near the bottom are not as bright or dark as the ones near the ruler marks. This is because the lower portion of the interferogram is going out of focus; out of focus means less interference. By carefully calculating the area of greatest contrast, optical profilometers determine the point that has best focus.

    In practice, an optical profiler scans the material vertically. As the material in the field of view passes through the focal plane, it creates interference. Each level of height in the test material reaches optimal focus (and therefore greatest interference and contrast) at a different time. With well-calibrated optical profilers, accuracy well below a nanometer is possible. A nanometer is ten Angstroms.

    In a ZYGO profilometer, each data point is monitored to determine its most precise focal point. Every pixel's height is measured relative to every other by comparing its maximum contrast (point of focus) relative to the pixels around it – producing a very sensitive surface measurement.

    What is the Purpose of Optical Profiling?

    Non-contact profilometers are used in many situations where micro-measurement of surface variations are essential. Industries such as optics and data storage use highly polished surfaces that are measured with interference profilometers.

    • Optics metrology is focused on lens and mirror surface finish and surface roughness, rate of curvature, and sometimes surface texture. Some binary lenses and diffraction gratings require measurements of volume, slope and radius of curvature.
    • Data storage surface metrology concentrates not only on surface finish roughness, but also the surface shape of the disk at the edge, and the geometry of laser-textured bumps for minimising 'stiction' the adhesive force of the read head to the magnetized surface. Bump spacing, their alignment to a grid, peak-to-valleys, consistency, and general bump shape are measured.
    • Form & Roughness of Precision Parts – Precision machined flats, sealing surfaces, conical seats, steps and free-form shapes are all measured for wide variety of parameters. These include flatness, angle, deviation from ideal form, roughness, and microstructure.
    • Surface Finish – Zygo profilers measure surface roughness with better than nanometer and micro-inch specification - well below the level of detection by the human eye or tactile sensation.
    • Step Height – Zygo surface profilers can measure height difference between two discontinuous planes of up to 20 mm. It is also possible to measure the angle of the surfaces using this technique.
    • Dynamic Metrology – MEMS research and production requires precise surface measurement and characterisation of micro-devices. Zygo profilers provide complete MEMS metrology on a single platform - with sub-nanometer resolution.
    • Films – The top surface and film thickness data analysis capabilities enable precise measurement of various surfaces in multilayer processes. Special algorithms single out the film's top surface to measure its topography, while film thickness analyses identify the film's top surface and the substrate surface to calculate a film thickness map. These special analyses also permit topography measurement of the substrate surface.

    surfactextureparameters

    This handbook contains definitions and illustrated explanations of roughness, waviness, spacing, and hybrid parameters, more than 100 in all. To request a pdf copy click here.

    Optical profiling can be used to measure surface finish, roughness and shape on many surfaces, so long as enough light is reflected back into the objective from the surface. Some optical profilers may be limited when it comes to measuring very high slopes, where the light is reflected away from the objective, unless the slope has enough texture to reflect light back to the objective. Fortunately, the high slope limitation has been virtually eliminated with the introduction of Zygo's Nexview 3D Optical Surface Profiler, which is able to measure all types of surfaces, from rough to super smooth, including thin films, steep slopes, and large steps.

    Optical profiling has been used to measure paper, plastic, epoxies, metals, glass, paint and ink. It is useful in analysing the fingerprints of materials processing, such as the cumulative effects of sawing, grinding and polishing. It is useful in wear analysis, since it is able to calculate the volume of voids and scratches.

    Optical profiling is used in a number of precision-engineering surface measurement situations:

    • for large step height measurement, where a stylus profiler may have difficulty reaching each step
    • where a three dimensional map of a surface is important, such as:
      • in determining the average heights of different areas
      • where sampling location selection may lead to varying results
      • where volume is a necessary parameter, such as measuring voids
      • a soft or fragile surface may be altered by contact measurements
    • where surface roughness, as opposed to linear roughness, must be known
    • in some cases, transparent films can be measured at their top and bottom surfaces

    Optical profiling is quicker than stylus profiling in measuring surface areas. Areas are measured with stylus profilers with a series of parallel linear measurements. Previously, stylus profilers had an advantage of permitting long profiles, using extended stage travel. However, ZYGO optical profilers have larger fields of view and more pixels per measurement than typical optical profilers: therefore our profilers can measure longer profiles than previously possible in a single optical surface measurement acquisition.

    Optical profiling is easy to use: the highly automated optical profilers are loaded with ease-of-use features that permit accurate and repeatable measurements with far less operator training.

    Optical Profilers from Zygo – A History

    Heterodyne Profiler -

    Maxim 5700 – Micro Fizeau, tip/tilt in the head, PSI, HPUX system controllers.

    Maxim 3D – PSI, 2 wavelength for rougher surfaces, HPUX system controllers.

    NewView 100 – The first Scanning White Light Interferometer (SWLI) from Zygo, uses Frequency Domain Analysis to achieve high resolution over the entire scan range. 100 micron scan using PiFoc, open loop, finite conjugate objectives. HPUX system controllers. Standard microscope stand. Wyko RST was around during this time.

    NewView 200 – Switch to infinite conjugate objectives that work with all future NewViews, Nexviews and ZeGages. Open loop and Closed loop PiFoc piezo scanner, 100 micron range. HPUX system controllers. Standard microscope stand. Extended scan implemented.

    NewView 5000 series – Introduction of “A” frame designed using Finite Element Analysis (FEA) to minimise vibrations.  Used on all subsequent NewView systems.  Has extended scan to measure up to 5000 microns. Variable zoom. End of PC upgrade route due to frame grabber board no longer being available.

    NewView 6000 series – Introduction of CAN-BUS electronics and away from Type II board. Fixed Zoom and zoom turret available (6300).

    NewView 600 – Low cost single objective system, manual stages.

    NewView 700 – Low cost single objective system, manual stages.

    NewView 7000 series –

    ZeMapper – Available after ZeMetrics acquisition. Good for large area parts such as hard disk drive substrates. Used ZeMaps software. Discontinued 2014

    ZeScope - Available after ZeMetrics acquisition. Good for large volume parts such as larger engineering parts. Used ZeMaps software. Discontinued 2014

    ZeGage -  Jointly developed by the Zygo and new ZeMetrics teams. Used NewView optical head and ZeMaps software. Z scanner is non-piezo based. Migrating to new Mx software.

    Nexview – Latest top of the range flagship optical profiler form Zygo. First to use new Mx software. Has many new features including crash protection, colour imaging, “More Data” concept,  Smart PSI (Phase Shifting Interferometry), Oversampling, New 5.5x and 2.75x objectives, Parfocal imaging, Full Automation. Available for demonstration by Lambda Photometrics.

    NewView 8000 series – The latest series of Optical Profilers from Zygo. Uses the new Mx software. Has many new features in common with the Nexview including crash protection, “More Data” concept, Oversampling, New 5.5x and 2.75x objectives, Parfocal imaging.

    All features can be demonstrated on the Nexview which is available for demonstration by Lambda Photometrics Ltd.

    If you have further questions please contact our Metrology team on 01582 764334  or click to email.

     

     

     

     

  • Precision Alignment of IR Lenses using visible and IR laser sources within a Laser Alignment and Assembly Station™

    Overview

    Precision Alignment of IR Lenses can be achieved using a Laser Alignment and Assembly Station™ (LAS™). It is a precision instrument for active alignment of lenses used in UV, VIS or MWIR applications. The LAS-IR™ system offers improved quality and output by increasing the flexibility of the optical module to include two laser sources, visible and IR in a single package. The user is able to choose from any two of the following wavelengths: 532nm, 635nm, 3.39um, or 10.6um, (one visible and one IR).

    After measuring and adjusting alignment by reflecting visible laser from the top surface, the user can select the IR wavelength to reflect from the bottom surface of an IR optic and confirm its alignment or wedge in the lens.

    PL1

    Common Categorisation of Lenses and Their Alignment Tolerances:

    Commercial >10 microns

    Precision 1-10 microns

    Ultra-Precision  <1 micron

    Theory of Operation

    The LAS™ systems measure the error between the optical axis of a lens with respect to the rotational axis of a precision air bearing. A centring and tip-tilt stage is mounted onto the air bearing to assist in bringing the mechanical axis of a lens-housing into collinear alignment with the rotation axis of the air bearing. Once you have aligned your housing, simply place the lens to be mounted into the housing and use the LAS™ system to centre your lens.

    PL2

    Figure 1: Alignment of Mechanical Housing to Optical Axis

    The LAS™ systems operate by reflecting a low power laser beam off of any lens surface being aligned or measured. Reflected alignment measurements of each lens surface are much more sensitive than measurements using a transmitted beam. If the lens is not centred properly, the reflected beam will reflect away from the optical axis. As the air bearing is rotated, the reflected beam will subtend a cone and this will be focused as a circle/orbit onto the CCD array.

    PL3

    Figure 2: Schematic of Laser Run-Out 

    The optical module emits a focused laser test beam which is aligned with the rotation axis of the air bearing. This focused beam will reflect off the lens being aligned and return to a CCD array for measurement. Because the laser beam is converging, it allows the operator the option of reflecting either a confocal or normal beam. See Figure 3 for a description of Normal and Confocal reflections. By utilizing either of these reflections, the LAS™ systems can take measurements from lens radius from +/- 2 mm to infinity of spherical, aspherical or cylindrical surfaces without changing objectives, hence retaining the same optical axis from lens-to-lens for ultimate accuracy.

    PL4

    Figure 3: Normal (left) and Confocal Reflections (right) for a Convex Lens

    Accurate measurements from the sample lens’ bottom surface and lenses below it are also obtainable. This insures that all optical surfaces are in proper alignment.

    PL5

    Figure 4: Focusing on Top and Bottom Surfaces 

    After the CCD array captures the circular orbit of the reflected beam, the CalcuLens™ software measures the diameter of this orbit and a measurement of the lens centration is calculated and provided instantly to the operator. Lens data can be imported to CalcuLens™ software from design software (Zemax) or entered manually.

    PL6

    Figure 5: CalcuLens™ Software Screen Capture of the Reflected Beam

    The LAS™ system is a very accurate tool for aligning precision lenses into your assembly. Learning to use this high accuracy instrument is easy. Anyone can be properly trained to start assembling lenses in just a few hours.

     

  • Basics of Raman Spectroscopy

    Laser - Creating Raman Scatter

    TN_01In Raman spectroscopy, it is essential to utilise a clean, narrow bandwidth laser due to the fact that the quality of the Raman peaks are directly affected by the sharpness and stability of the delivered light source. The i-Raman® spectrometer system features a patented CleanLaze® technology with a linewidth < 0.3nm when equipped with our 785nm and 830nm laser. This technology results in the correct center wavelength and avoids the phenomenon of “mode hopping.” In addition, the laser output power can be adjusted in the software from 0-100%, allowing you to maximise the signal-to-noise ratio and minimise integration time.

    Laser lifetime of 10,000 hours ensures quality data for years to come!

    Filter - Collects Data within 175cm-1 of the Rayleigh Line

    The centre wavelength of the laser line is precisely maintained even when the peak power is increased by utilising a series of high end filters. A laser line filter is used to clean up any side bands and ensure a narrow excitation is delivered to the sample by removing all secondary excitation lines before exciting the sample. The light collected from the sample is then filtered via a notch filter. Finally, an ultra steep long pass filter further removes lingering laser lines to allow accurate measurement of Raman peaks as close as 175cm-1 from the Rayleigh line. An E-grade filter upgrade is available, allowing the measurement of Raman peaks as close as 65cm-1 from the Rayleigh line.

    Spectrometer - Optimised for Raman Spectroscopy

    TN_02The spectrometer design in the i-Raman® is dedicated for Raman applications. You can customise your spectrometer by choosing from a variety of excitation wavelengths. In addition, each configuration can be further customised for your individual detection needs. Choose from wider spectral range or high resolution optimised systems. Research grade spectral resolution of 3cm-1 can be achieved with our double pass transmission optics. Most Raman applications do not require such tight resolution, so a wider spectral range would be the better choice in that case. The high-throughput optical layout of all i-Raman® configurations are ideal for those low-light level Raman applications.

    Probe - Easy Transition Between Sample Types

    The probe allows for measurement of various materials in the form of liquids, gels, powders, or solids under both lab conditions (lab grade) or demanding environmental conditions (industrial grade). Constructed with state-of-the-art telecom packaging techniques, the probe has a flexible fiber coupling encased in a durable protective jacketing material which delivers Rayleigh scatter rejection as high as 10 photons per billion. Wavelength excitation probes come in 532nm, 785nm, or 830nm.

    Custom wavelength excitation probes available.

    Software

    B&W Tek offers comprehensive software packages that provide solutions for Raman application needs. Powerful calculations, easy data management, and user friendly, easy-to-follow work flow are all at the tips of your fingers.TN_03

    BWSpec™ is the foundation for all B&W Tek software platforms and comes standard with every Raman spectrometer. Built on the proven BWSpec™ platform, BWID™ (optional) is optimized for identification and verification of materials. For industrial Raman applications that require federal compliance: BWID™- Pharma (optional) supports all requirements for FDA 21 CFR Part 11 Compliance.

    TN_04The most recent addition to B&W Tek’s software portfolio is BWIQ™ chemometrics software for use with the i-Raman® Plus and other high resolution Raman products. BWIQ™ is a multivariate analysis software package which can analyze spectral data and discover internal relationships between spectra and response data or spectra and sample classes. By coupling new and transitional chemometric methods with cutting edge computer science technology such as sparse linear algebra algorithms, BWIQ™ represents the next generation in speed, accuracy, and performance.

  • Luna OBR 5T-50 new/lower cost for production

    Announcing a new Optical Backscatter Reflectometer™ that’s 200 times faster than competing solutions.

    Luna Technologies’ OBR 5T-50 is a fast, easy-to-use, low-cost precision instrument developed to meet market requirements for higher speed and a simplified user interface. It’s designed for manufacturers, research facilities and university labs.

    The OBR 5T-50 reduces cost and complexity, while increasing throughput by measuring the Insertion Loss (IL) and Return Loss (RL) distribution of passive optical components and modules such as optical cables, connectors, switches, couplers, and planar lightwave circuits.

    OBR 5T-50 Advantages:

    Optical Backscatter Reflectometer
    • 12Hz real-time measurement acquisition & display
    • 8.5metre device length (customisable)
    • 20micron spatial measurement resolution
    • No dead zone
    • Automatic identification and real-time logging of RL/IL event locations
    • Customisable at little or no extra cost (e.g. 17m device length at 6Hz measurement rate)
    • Luna’s lowest cost reflectometer

    “The OBR 5T-50 is the latest in the company’s line of products for fibre-optic testing, expanding our offering in the fibre-optic testing market with an industry-leading combination of measurement, speed, range and accuracy,” said My Chung, Luna’s CEO. “This highly specialised equipment is designed to fulfil the market needs not met by our current OBR products, with higher speed and at a lower cost. It’s the latest example of Luna developing technology to meet the exacting needs of customers in a variety of settings.”

    To discuss your application and arrange a demo please contact Matthew Ball on 01582 764 334 or send an email to contact@lambdaphoto.co.uk.

     

    Lambda Photometrics Ltd is a leading UK Distributor for Laser and Light based products in areas including Optics, Electro-optic Testing, Spectroscopy, Machine Vision, Optical Metrology, Instrumentation, Microscopy and Pulsed Xenon Light Systems.

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