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Gamma Scientific

LED/SSL Testing

RadOMA CCD Array Spectroradiometers

With over 40 years of experience in developing commercial LED testing instruments, Gamma Scientific is trusted by the world’s leading organizations to provide accurate and reliable results.

Gamma Scientific LED testing systems are built around high performance spectrometers that have been engineered to produce accurate, repeatable measurements in the most demanding production line environments.

With near real-time measurement and powerful analysis software, Gamma Scientific systems are designed to handle 24 hour operation on the production floor. Multiple configurations cover a wide spectral range from ultraviolet to near infrared, and are easily customized to match unique testing requirements.

The Standard in LED Testing Instruments for Over 40 Years

  • Gamma Scientific instruments have been used for LED testing since 1973, when photometers from Gamma Scientific were used by Hewlett Packard to accurately measure optical properties of Red LEDs

  • Gamma Scientific developed the first high-performance, computer controlled spectroradiometers for LED testing

  • Instruments from Gamma Scientific were used in the invention and development of OLEDs

  • Gamma Scientific has been designing integrating spheres since the 1960s

  • The Gamma Scientific Laboratory is accredited by NVLAP (NVLAP Lab Code 200823-0) for Energy Efficient Lighting Products (including LM-79 and LM-80) in accordance with ISO-IEC 17025

  • Gamma Scientific supplies national metrology institutes (NMI’s) with reference detectors that are used as working standards

  • LED test instrument calibration is performed at Gamma Scientific’s accredited laboratory using NIST traceable standards

LED/SSL Testing

Photometers and Radiometers

UDT Instruments, a division of Gamma Scientific, offers an extensive selection of photometers, radiometers, reference standard detector systems and transimpedance amplifiers to meet your testing requirements.

Combining our wide range of optometers, detectors and accessories, with our state-of-the-art calibration facilities, allows our applications engineers to assemble and configure custom systems for nearly any project.

System Configuration Guide

Learn how to configure a photometer or radiometer system to meet your testing requirements with this free guide from Gamma Scientific.

What’s in the Guide?

  • Definitions of the most important terms in photometry

  • Photometric to radiometric conversion factors

  • How to specify a photometer system

  • Photometric quantity units, symbols and abbreviations

What’s in the Guide?

  • Definitions of the most important terms in radiometry

  • How to specify a radiometer system

  • Radiometric quantity units, symbols and abbreviations

  • Calibration by transfer of standards

Photometers and Radiometers


Complete your inspections faster, and achieve higher standards of quality with accurate, repeatable reflectance and transmission measurement systems from Gamma Scientific.

Controlled optical geometry and industry leading spectroradiometer performance offer quick, accurate reflection/transmission measurements for any glass or polished transmissive element.

When measuring reflectance, Gamma Scientific’s unique technology allows manufacturers to perform single sided inspection on the first surface while excluding the second surface.

With handheld, semi-automatic and fully automated options, Gamma Scientific reflectometers have tremendous flexibility and can be used for R&D, QA and production line testing.

GS-191SA-1045 Semi-Automated Dual Angle Reflectance Measurement Systems

GS-191FA-1045 Rotary Reflectance Measurement Systems

Specular and Diffuse Measurement Systems for Measuring Virtually Any Sample

Gamma Scientific provides a unique, high performance option for reflectance and transmission testing. These systems capture complete spectral and colorimetric properties of thin film coatings with scan times typically less than one second.

Multi-layer film thickness and sample flatness can also be monitored in parallel.


Reflectance and Transmission test systems from Gamma Scientific are available in several configurations. Depending on the sample type and desired measurement result, a variety of system configurations are available for testing either polished (specular) or rough (diffuse) samples. A production selection guide is included in this brochure to help in configuring the best system for your needs.


These systems are ideal for manufacturers who need to obtain fast and accurate measurements of flat panel display glass, anti-reflection coating inspection, photovoltaic (solar cell) coatings, optical filters, lens coatings, paint samples, diffuse plastics and more.


 Regardless of the sample, Gamma Scientific offers a solution for your reflectance or transmission measurement needs.


  • Gamma Scientific Model 191 Series Reflectometer Heads isolate the first surface reflection

  • The second surface is completely eliminated in a non-destructive manner

  • Light reflecting off each surface will be slightly offset

  • This offset is used to mechanically block light reflected off lower surfaces

Gamma Semi-Automatic Anti-Reflectance Measurement (GSAARMeas) Software

  • Programmable, Multi-Location Reflectance Measurement

  • Real-Time Color Charts

  • Binning and Pass/Fail Compatibility

  • Automated Calibration

  • Simultaneous 10° and 45° Measurements

  • Multi-Layer Film Thickness, n & k Characterization

  • Sample Flatness Measurement

  • Bar Code Reader (optional)

Selection Guide

Reflectance and Transmission Measurement System Specifications


Display Test and Measurement

Gamma Scientific provides precision display testing solutions that are used by companies worldwide to accurately measure reflectance, color characteristics and polarization.

Custom solutions are available to calibrate monitors, video walls, near-to-eye displays and 3D screens. Gamma Scientific also provides equipment to test LEDs, light engines, color filters, back lights and display glass.

Display test systems from Gamma Scientific include high-speed reflectance measurement systems, robotic display measurement systems, spectroradiometers and luminance meters.

With an in-house, ISO/IEC 17025: 2005, NVLAP accredited laboratory (NVLAP Lab Code 200823-0), Gamma Scientific provides testing services for displays and display components.

Display testing

NVIS Testing

GS-1290-NVIS Dual Stage Cooled Spectroradiometers

RadOMA Dual Stage Cooled CCD Array Spectroradiometers are designed for manufacturers of military displays and other lighted instrumentation used in conjunction with night vision imaging systems (NVIS) that require their products to conform to MIL-STD-3009.

While the MIL-SPEC and competitive systems target a 10:1 signal-to-noise (SNR) measurement ratio, our GS-1290-NVIS spectroradiometers are designed and built to deliver SNR of 100:1 or greater.

This increase in the performance level in the metrology system enables manufacturers to ensure that that their products are fully compliant with the MIL-SPEC, without the downside of unnecessarily failing good product.


  • Measurements down to 0.00015 cd/m2

  • Exceptional accuracy via high-resolution bandwidth coverage

  • Near-real-time measurement and high resolution: 0.6 nm/pixel

  • Spectral range 360-930 nm or 360-1100 nm

  • Six aperture RadOMAcam® telescope which projects the actual measurement spot onto the DUT for easy alignment

  • USB 2.0 interface and Windows-based Light Touch NVIS control/analysis software

  • NIST-traceable accuracy

  • Direct Excel export for data and graphs

  • Pass/Fail reporting per MIL specifications

  • Self-calibrated: eliminates cost with downtime

  • Optional X-Y translation stage

  • Zoomable CIE Chromaticity plotting with NVIS type outlines

GS-1290-NVIS Dual Stage Cooled Spectroradiometer Specifications

1: Measuring 100% linearly polarized light through a Glan-Thompson Prism
2: Sensitivities are for a 10:1 signal-to-noise ratio based on the percent coefficient of variance measuring the luminance of a CIE Illuminant A source.
3: Tamron 180mm macro 1:3:5

RadOMA CCD Array Spectroradiometers

Our line of RadOMA CCD Array Spectroradiometers provide high accuracy and near perfect repeatability for laboratory use, quality control applications and high speed LED testing.

Multiple models cover UV, Visible and Near-infrared applications.

NVIS Testing

Camera Calibration

SpectralLED Tunable LED Light Source

The SpectralLED™ Tunable LED Light Source provides unprecedented resolution and accuracy for camera and image sensor calibration.

Designed completely from the ground up, this light source builds upon over fifteen years of experience manufacturing LED based light sources.

Incorporating some of the newest and brightest surface-mount LEDs available, the SpectralLED™ delivers a nearly continuous spectrum comprised of 30 discrete wavelength LEDs. This allows for an unprecedented color gamut and applications otherwise impossible for traditional halogen or LED light sources.

SpectralLED™ light sources simplify the calibration process by allowing you to quickly simulate and change between a huge variety of traditional light sources. Select a preset CIE Illuminant or Macbeth™ / X-RITE™ color patch, or import your own spectrum and let the internal RMS spectral fitting find the best match instantly.


  • Unprecedented Resolution and Accuracy – 30 Discrete LED Wavelengths Covering the Visible and NIR

  • Powerful Synthesis Engine – Quickly Simulate any CIE Illuminant or Macbeth™ / X-RITE™ Color Patch

  • Flexible Interface – Built-in RMS Spectral Fitting for Simulation of Any User Imported Spectra

  • Uniform 75mm Radiance Output Port or Optional Baffle Tube for Irradiance

  • Easily Adaptable – for Automated Test Systems and Production Line Integration

  • Pure DC Constant Current Drivers and Built-in Optical Feedback Photodiode System – Ensure Accurate Output in Real Time

  • On-board Thermal Electric Cooler and Feedback – for LED Temperature Control

  • ISO/IEC 17025 NVLAP Calibration Laboratory (Lab Code 200823-0) – Ensures Superior Wavelength and Color Accuracy

Unprecedented Resolution and Accuracy for Camera and Image Sensor Calibration

Light sources are only as accurate as the calibration. As a world leader in high performance spectroradiometers, and with an in-house ISO/IEC 17025 NVLAP Accredited Calibration Laboratory (Lab Code 200823-0), you can trust the NIST calibration that comes programmed into every SpectralLED™ source.

Replace multiple instruments with a single device. With a fully spectrally tunable output spectrum, all you need is one SpectralLED™ to generate any arbitrary spectral power distribution. Whether it be blackbody, daylight, fluorescent, LED, or something completely unique, the SpectralLED™ can give you an accurate match.

Replace monochromators with a solid stage design. By sweeping through individual LED channels, the SpectralLED™ can emulate a traditional monochromator light source. With no moving parts and no halogen input illumination, the solid state SpectralLED™ is the clear choice for demanding applications.

Unlimited possibilities for limitless spectra. With independent 16-bit control on 30 LED channels, there are virtually infinite possibilities for what the SpectralLED™ can do for you. Compared with other “next-gen” LED light sources, the SpectralLED™ offers more channels, brighter output, higher accuracy, and more powerful features for simulation. No external software is required, the SpectralLED™ firmware controls RMS fitting, calibration storage, and presets. Direct integrating into production lines or test systems is easy with universally compatible USB and RS-232 interfaces.

Gamma Scientific SpectralLED™ light sources feature a proprietary electrical design for superior accuracy and reliability. The completely redesigned drive electronics provide a pure DC constant current LED drive with floating differential sensing. This means there is no flicker and no uncertainty in the drive current. Couple that with built-in optical feedback, and the SpectralLED™ is able to accurately control optical output power to within a fraction of a percent. On-board thermal control maintains the LED substrate temperature to ensure spectrum is stable even at high drive currents.

SpectralLED™ Illuminant A (Blackbody) Simulation using RMS Spectrum Fitting. Target (Blue) Output (Red)

Measurement Applications


  • White Balance

  • Quantum Efficiency

  • Spatial Non-Uniformity

  • Pixel Defects

  • Cross Talk

  • Vignetting Correction

  • Sensitivity

  • Responsivity

  • Signal-to-Noise

  • Linearity

  • ISO Speed

  • Saturation Exposure

  • Dynamic Range

SpectralLED™ Illuminant D65 (Daylight 6500K) Simulation using RMS Spectrum Fitting. Target (Blue) Output (Red)

Camera Calibration

Industry Applications

  • Camera and Image Sensor Calibration (CCD, CMOS, etc.)

  • Ambient Light Sensor Calibration

  • Detector Responsivity

  • OEM Camera Manufacturing

  • Spectrum/Illuminant Simulation

  • Diagnostic Medical Imaging

  • Technical and Industrial Photography

Laser Power Meters

UDT Instruments offers two different systems for laser power measurement based on our S470 flexOptometer and Model 221 silicon sensor.

The uRAD-FL Laser Power Meter bundle combines a broadband silicon sensor with an integrating sphere to provide simple and accurate laser power measurements. The 150mm diameter sphere attenuates the beam to allow measurement of higher-power devices, reducing sensitivity to beam polarization and alignment. The sphere accepts beams of up to 19 mm (0.75″) diameter.

The uRAD-FLD Laser Power Meter bundle combines a broadband silicon sensor with a multilayer diffuser-type laser power attenuator to provide simple and accurate laser power measurements. Maximum beam size is determined by the attenuator’s 7mm diameter aperture.

Both system’s power (radiant flux) calibration is programmed into the benchtop optometer. Measurement results are displayed by the optometer in units of Watts (W), and digital data can be acquired directly via PC. The system can also be configured to support “single-shot” energy measurements of individual laser pulses, in units of Joules (J).

uRAD-FL Laser Power Meter Components

  • Power MeterModel S470 flexOptometer: Benchtop Power Meter, Single Channel; IEEE-488, RS-232, RS-485, USB

  • Radiant Flux Sensor Model 221: Silicon sensor; 1cm2 area; adapted to the Model 2500L sphere for laser power (radiant flux) measurement

  • Integrating SphereModel 2500L: 150 mm (6″) diameter; 19 mm diameter sample port; for collimated or slightly-divergent beams

  • Single-Point Laser Power Calibration – U68072: At specified laser wavelength in range: 350 – 1100nm; NIST Traceable in units of Watts (W)

  • Alternative Power Meter – Model S471: Portable Power Meter with LCD display, RS-232 Interface; 50 programmable cals; AC or Battery power

uRAD-FLD Laser Power Meter Components

  • Power Meter Model S470 flexOptometer: Benchtop Power Meter, Single Channel; IEEE-488, RS-232, RS-485, USB

  • Radiant Flux Sensor Model 221: Silicon sensor; 1cm2 area; adapted to the Model 2550 attenuator for laser power (radiant flux) measurement

  • Laser Power Attenuator – Model 2550 optical attenuator: Diffuser type, 3 layers; 7 mm diameter aperture

  • Single-Point Laser Power Calibration – U68072: At specified laser wavelength in range: 350 – 1100nm; NIST Traceable in units of Watts (W)

  • Alternative Power Meter – Model S471: Portable Power Meter with LCD display, RS-232 Interface; 50 programmable cals; AC or Battery power

Laser Power
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