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Optics Laboratories


TÜBİTAK UME Optics Laboratory continues its works under five sub-divisions in the field of scientific metrology. These fields  are named as; Detector Radiometry, Photometry, Spectrophotometry, Fiber Optic and Photovoltaic. Activities carried out in the TÜBİTAK UME Optics Laboratory briefly are as follows:

  • In the field of Detector Radiometry:
    • Optical characterization  and primary level calibrations of radiation sources and detectors used in ultraviolet (UV), visible (VIS) and infrared (IR) regions of  the electromagnetic spectra,
  •  In the field of Photometry:
    • Optical characterization and primary level calibration of light sources and measuring instruments used in the visible region of the electromagnetic spectra,
  • In the field of Spectrophotometry:
    • Optical characterisations of  physical properties of materials (reflectance, transmittance, color and brightness,..) and calibration of reference standards and measuring instruments,
  • In the field of Fiber Optic:
    • Optical power, attenuation and length characterizations of single mode fiber optic cables used in telecommunication wavelengths and calibration of reference standards and measuring instruments,
  • In the field of Photovoltaics:
    • Performance and safety test measurements in accordance with the  IEC 61215-2 and IEC 61730-2 standards.

Besides above activities, TÜBİTAK UME Optics Laboratory also with the developed many cooperation programs, in the field of optical  measurements offers its know hows and technology infrastructure to the country's industry. Moreover, in line with the technological developments, in order to meet the potential measurement demands that may arise within the country, TÜBİTAK UME Optics Laboratory with R&D works constantly improves its mesurement systems.

The works conducted in the Detector Radiometry, Photometry, Spectrophotometry, Fiber Optic and Photovoltaic divisions of the TÜBİTAK UME Optics Laboratory are listed below.



The studies related to the detection of optical radiation at the optical range of the electromagnetic spectrum (UV, VIS, IR) are the interest of this discipline. Spectroradiometric characterization of radiation sources such as optical energy, power, radiance and irradiance and responsivity of radiometers are investigated under “Detector Radiometry” division. Quantum efficiency, deficiency, dynamic range and surface homogeneity like optical characterization of detectors are also performed in this division.

Measurements (spectrally) performed in Detector Radiometry Division are: Optical Energy (W∙s), Power (W), Radiance (W/(sr∙m2), Irradiance (W/m2), Optical Power Responsivity (A/W), and Irradiance Responsivity (A/(W/m2)). Traceability chain of the given capabilities are provided by the measurement of the basic unit (optical power) in the radiometry by using primary level measurement system “Electrical Substitution Cryogenic Radiometer (ESCR)”.

Calibration Services given by Detector Radiometry Division are:

  • Spectral Optical Energy of Pulsed Radiation Sources ((W∙s)/nm)
  • Spectral Optical Energy Responsivity Factor of Energy Meters (Measuring unit/((W∙s)/nm))
  • Spectral Optical Power of Radiation Sources (W/nm)
  • Spectral Optical Power Responsivity Factor of Radiometers (Measuring Unit/(W∙nm))
  • Spectral Radiance of Radiation Sources (W/(m2∙sr∙nm))
  • Spectral Irradiance of Radiation Sources, (W/(m2∙nm))
  • Spectral Irradiance Responsivity of Radiometers (Measuring Unit/(W/(m2∙nm)))



Spectrophotometry is a science that deals with the quantitative determination of reflectance, transmittance, absorbance, color and gloss like physical properties of materials. In this context covering the measurements in ultraviolet (UV), visible (VIS) and infrared (IR) regions of the electromagnetic spectra, spectrophotometry has wide variaty of  scientific applications in physics, materials science, chemistry, biochemistry, molecular biology ect.

In spectrophotometry, in order to  measure the spectral reflectance, transmittance and absorbance of materials and to determine the its color and gloss properties various spectrophotometric measurement techniques are used.  These techniques, depending on the geometrical properties and surface structure of the materials  basically consist of accessories and reference standards used in conjunction with the spectrometer.

Therefore,  the accuracy of the measurements in spectrophotometry  basically requires  both the complete calibration of spectrometer (wavelength, spectrophotometric accuracy, stray light,...)  and   the calibrations of the artafects used as a reference for the reflectance, transmittance and absorbance measurements units.   The calibration of spectrophotometer is done according to the ASTM standards and calibrations of reference standards are done with the absolute goniorefletometer. Reference standards for the gloss and color  which derive from material’s regular and diffuse reflectance physical properties are  therefore treacable to  these (regular and diffuse reflectance) reference standards.


Calibration Services given by Spectrophotometry Division are:

  • Spectrophotometer Calibration (UV/VIS)
  • Wavelength Measurements of Light Sources
  • Spectral Specular Transmittance (250 nm – 2500 nm)
  • Total Transmittance (250 nm – 2500 nm)
  • Spectral Specular Reflectance (250 nm – 2500 nm)
  • Spectral Diffuse Reflectance (250 nm – 2500 nm)
  • Colour Tiles Calibrations at Standard Geometries of d:8°, d:0° and 0°:45° and Standard Observations of 2° and 10° (CIEXYZ, CIExy, CIELAB)
  • Colorimeter Calibrations at Standard Geometries of d:8°, d:0° and 0°:45° (Delta E)
  • Gloss Calibrations of Meters and Plates (Standard Angles: 20°, 60° and 85°)



Photometry is a science of the measurement of light within the wavelength range from 380 nm to 780 nm, which is the called as the visible region of the human eye. This section is based on the realization of the luminous intensity unit of candela (cd), which is one of the seven SI (Systeme International) based units. Candela was realized on photometric bench using interferometric distance measurement system and reference photometer head (filter-radiometer) traceable to TÜBİTAK UME primary level Electrical Substitution Cryogenic Radiometer. Calibration of light sources within the visible range and characterization of the photometers used in the photometric measurements of these light sources are carried out in the photometry laboratory.

Measurement units that can be provided in the photometry laboratory are given below:

  • Luminous flux (lm)
  • Luminous intensity (cd)
  • Illuminance (lx)
  • Luminance (cd/m2)

Traceabilities for all the measurement units are based on the Electrical Substitution Cryogenic Radiometer based optical power scale.

A New Definition of the Candela

The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W-1, which is equal to cd sr W-1, or cd sr kg-1 m-2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs.

The new definition of Candela (cd), which links SI units to the universal constants, does not bring any change in its realization and traceability.  The Kcd ( 683 lm/W) conversion coefficient used for transferring the radiometric scales obtained by the primary level measurement standard (Electrical Substitution Cryogenic Radiometer) to the scales in photometric scales is the same but only expressed in terms of (∆nCs) ² (cesium atom transition frequency), h (plank constant) and c (light velocity) constants.


Calibration Services Performed in Photometry Division:

  • Luminous Flux Measurements (Tungsten-Filament Lamp, 2856 K) (lm)
  • Luminous Intensity Measurements (cd)
  • Color Coordinate Measurements of Light Sources (CIE-xy, CIE-u'v')
  • Color Temperature Measurements of Light Sources (K)
  • Luminance Responsivity Measurements (cd/m2)
  • Luminance Measurements (cd/m2)
  • Illuminance (Luxmeter) (lx) 
  • Illuminance Responsivity (Photometer Head) (A/lx)
  • Luminous Exposure (Flash Source), (lx∙s)



In the fiber optic laboratory; studies are carried out for the calibration of fiber optic power meters, sensors, attenuators and OTDR (Optical Time Domain Reflectometer) devices used in the measurement of single-mode fiber optic links, which have an important place in telecommunication, security, communication, broadcast technologies and applications. Traceabilities of standards used in fiber optic power (W) and attenuation (dB) measurements are based on the sphere radiometer having a InGaAs sensor, which is calibrated against the absolute cryogenic radiometer of TÜBİTAK UME. Attenuation coefficient (dB/km) and length (m) standards used in OTDR calibrations are traceable to the TÜBİTAK UME optical power and time (distance) scales. Calibrations of single-mode OTDR and fiber optic power meters are performed according to IEC 61746 and IEC 61351 standards, respectively.

Calibration Services Performed in Fiber Optic Laboratory:

  • Calibration of Single-Mode Fiber Optic Power Meters (1310 nm and 1550 nm)
  • Calibration of Single-Mode Attenuators (1310 nm and 1550 nm)
  • Calibration of Distance and Attenuation Scales of Single-Mode OTDRs (1310 nm and 1550 nm)



In the Photovoltaic Test Laboratory, which was established under TÜBİTAK UME and was accredited by TÜRKAK, the performance and safety tests of crystalline silicon and thin film based terrestrial photovoltaic PV modules can be carried out in accordance with the IEC 61215-2 and IEC 61730-2 standards.  In addition, the certification services can be provided in accordance with TS / EN / ISO 17025 standard. The calibrations of refrence standards to be used in PV test measurements systems are carried out with the TÜBİTAK UME primary level reference standards   whose accuracy is confirmed by international comparisons.


Calibration / Test Services of Photovoltaic Divison

  • Visual Inspection Test
  • Maximum Power Test
  • Insulation Resistance Test
  • Temperature Coefficients Test
  • Nominal Module Operating Temperature (NMOT) Test
  • Performance Test at STC and NMOT Conditions
  • Low Irradiance Performance Test
  • Outdoor Exposure Test
  • Hot-Spot Endurance Test
  • UV Preconditioning Test  (15kWh)
  • Thermal Cycling Test
  • Humidity Freeze Test
  • Damp Heat Test
  • Robustness of Termination Test
  • Wet Leakage Current Test
  • Mechanical Load Test
  • Hail Test
  • Bypass Diode Thermal Test
  • Bypass Diode Functionality Test
  • Stabilization Test
  • Accessibility Test
  • Cut Susceptibility Test
  • Ground Continuity Test
  • Impulse Voltage Test
  • Temperature Test
  • Fire Test
  • Reverse Current Overload Test
  • Module Breakage Test
  • Materials Creep Test
  • UV Test
  • Cold Conditioning Test
  • Dry Heat Conditioning Test
  • Spectral Responsivity  Measurement
  • Light Induced Degradation (LID) Test
  • Potential induced degradation (PID)  Test
  • Energy Rating Measurement
  • Reference Cell Calibration


International committees that TÜBİTAK UME Optic Laboratory has colloborations

  • EURAMET, Technical Committee TC-PR
  • COOMET, Technical Committee 1.7
  • GULFMET, Technical Committee


National and international standardization and accreditation organizations that TÜBİTAK UME Optic Laboratory has colloborations

  • DIN,
  • CIA,
  • ISO,
  • IEC,
  • TSE


Projects Conducted by TÜBİTAK UME Optics Laboratory


  • PV-Enerate ”Advanced PV energy rating (16ENG02)
  • Self-calibrating photodiodes for the radiometric linkage to fundamental constants (18SIB10 chipS · CALe)
  • Improvement of cryogenic measurement capability  (Ministry of Development, Action 9)
  • Investigation and establishment of reference radiometric measurement standards for low photon level measurements (Ministry of Development, Action 9)
  • Improvement of UV-VIS-NIR spectrophotometer measurement capability (Ministry of Development, Action 10.a)
  • Establishment of spectral light flux measurement system of LED based sources (Ministry of Development, Action 10.b)
  • Investigation and establishment of robot based absolute diffuse reflectance measurement System (MUYAS)
  • Establishment of near field goniometer measurement system for glow spatial distributions of LED based sources (Internal Project)
  • Construction of reference UV-B irradiance radiometer and establishement of calibration infrastructure (Internal Project)
  • Construction  of spectrally adjustable LED-based reference intagrating sphere (Internal Project)