BTS256-EF Light-Color-Spectral Meter

For photopic and scotopic illuminance, S/P Ratio, EVE factor, luminous color, color rendering index and light spectrum and flicker

BTS256-EF LED Luxmeter for LED Measurement from Gigahertz-Optic
The BTS256-EF is designed for portable high accuracy illuminance and luminous color measurements in all SSL and traditional lighting application areas thanks to its compact design, high-quality light sensor and precise cosine field of view.

What separates the BTS256-EF from the BTS256-E is its added ability to perform flicker measurements.

BiTec Light Sensor for More Accurate Light Measurement
One of the key features of the BTS256-EF is its BiTec light sensor. The BTS combines a silicon photodiode with a noise-free CMOS diode array. Through bilateral correction of measurement signals from both sensors, the BiTec sensor ensures extremely accurate photometric and spectral radiometric measurement values over a wide dynamic range.

Fast and Linear Silicon Photodiode Detector Plus Diode Array Detector
The traditional light detector employing a silicon diode and a photometric correction filter still provides the best dynamic range, linearity and response time . But it cannot perform color measurements and cannot actively adjust to the target light source's spectral function. This is why the Gigahertz Optik Bi-tech sensor is also equipped with a CMOS diode array detector that works with the filtered photodiode detector. Its precise spectral match to CIE photometric V(λ) spectral curve is optimized by correction using the diode array's measured spectral data.

Flicker Measurement
Flicker measurement entails detection of any AC component of the light signal with a 5kHz bandwidth. The BTS26-EF measures and displays flicker frequency, percent flicker and flicker index. The meter additionally performs a Fast Fourier Transformation in order to display other frequency components in the light signal. A technical note with more on flicker measurement is available by contacting the factory.

Optimized Signal to Noise Ratio
The noise component inherent in diode array light detectors has a significant effect on the signal to noise ratio (SNR) and hence on the quality of light measurement. A remote controlled shutter installed into the BiTec light sensor enables online compensation of the dark signals that are dependent on temperature and integration time.

Pulse Width Modulated (PWM) LED Lamps
The fast photodiode in the BiTec light sensor enables the BTS256-EF to automatically synchronize itself to the test light frequency operated in PWM mode.

Cosine Corrected Field of View
A cosine corrected field of view is absolutely necessary for accurate illuminance measurements. For extended illuminance sources the exactness of the cosine match has significant influence on the light meter measurement uncertainty. The BTS256-EF light meter is equipped with a 20mm diffuser window for a high level cosine match. Both BiTec light sensor detectors are centrally aligned behind the diffuser window ensuring the same viewing angle.

Quality Luxmeter
Through the cutting-edge Bi-Technology sensor concept, state-of-the-art electronics, online dark signal adjustment and the possibility to perform temperature compensation the BTS256-EF represents the next generation photometer for all light measurement applications.

Broad Range of Photometric and Colorimetric Measurement Quantities
A much broader diversity of measurands as those offered by conventional light meters is required for verification and testing of LEDs and SSL. The BTS256-EF measures the following quantities for complete characterization of any light source:

Flicker Measurands:

  • Ev (t) illuminance over time graphic
  • Ev,min minimum illuminance
  • Ev,max maximum illuminance
  • Flicker Percent (IES: RP-16-10, CIE: TN-006)
  • Flicker Index (IES: RP-16-10, CIE: TN-006)
  • F dom dominant flicker frequency
  • FFT FFT flicker frequencies
  • Pst short term flicker perceptibility (CIE: TN-006)
  • SVM stroboscopic visibility measure (CIE: TN-006)
  • Mp ASSIST flicker perception metric

Radiometric, Photometric, Colorimetric Measurands:

  • Ee (λ) spectral irradiance
  • Ev illuminance (fc & lux)
  • Es scotopic illuminance (fc & lux)
  • Ee irradiance
  • Es/Ev scotopic / photopic ratio
  • x; y    CIE 1931 color coordiantes
  • u'; v'  CIE 1976 color coordiantes
  • CCT correlated color temperature
  • Δuv deviation from the blackbody locus
  • X; Y; Z CIE color
  • Ra; R1..15 CRI - color rendering index
  • λdom dominant wavelength
  • pe purity
  • CIE 1931 color graphic with S-BTS256 software
  • CIE 1976 color graphic with S-BTS256 software
  • CRI Bar Plot with S-BTS256 software
  • λp peak wavelength
  • λc center wavelength
  • λs centroid wavelength
  • λ0.5   spectral half-width (FWHM)
  • TM-30-15 Rf fidelity index
  • TM-30-15 Rg gamut index
  • TM-30-15 Rf,h1..16 hue fidelity indices
  • TM-30-15 Rcs,h1..16 chroma change by hue indices with S-BTS256 software
  • TM-30-15 color vector graphic with S-BTS256 software
  • TM-30-15 Rf, Rg graphic with S-BTS256 software
  • Ez melanopic illuminance
  • Ee,z melanopic irradiance
  • Ev,mel melanopic daylight equivalent illuminance
  • Esc cyanopic illuminance
  • Ee,sc cyanopic irradiance
  • Emc chloropic illuminance
  • Ee,mc chloropic irradiance
  • Elc erythropic illuminance
  • Ee,lc erythropic irradiance

Data Displays for Standard Measurement Mode
Several displays where only the most necessary and common photometric measurements are shown are available. The cursor buttons are used to switch between the displays.

Flexible Expert User Displays
More experienced users can individually configure and save displays allowing any measurement quantity to be selected.

Info Display for Measurement Parameters
An information display is available that shows all relevant measurement and set-up parameters.

Easy Operation and Handling
Three control buttons with well-structured menu navigation make for easy and safe operation. In the standard measurement mode for example, no user selection is required - all common measurement quantities are displayed. In the expert mode the user has access to all measurement parameters.

Many Extra Useful Functions & Features

  • Time delay allows selectable time to move out of detector view before light measurement
  • Automatic display dimmer dims display during light measurement
  • Acoustic signal can be set to mark the end of a light measurement
  • Displays can be enlarged for easy reading across the room
  • Illuminance distribution map can be created using a PC and single measurement points stored in the meter. The measurement points can be progressively processed and saved.
  • Fast data logger measurement mode where time-clocked readings of the photodiode can be recorded at a maximum measurement rate up to 100ms
  • Second data logger measurement mode that enables time-clocked recording of all measurands including the spectral data
  • Date and real-time can be set
  • ¼-20 tripod stand socket on bottom panel
  • Diffuser window cap with leash
  • Lanyard
  • Splash proof

Use without PC
The BTS256-EF is equipped with all the functions necessary for computer-independent use. The rechargeable batteries provide eight hours of operation. The USB adapter cable can be used to recharge the battery even without a PC.

Use with PC
A USB2 interface is provided for use with a PC enabling data exchange and battery recharging. WiFi interface is also available – see BTS256-EF WiFi.

User Software
Supplied S-BTS256-E software offers all the functions necessary for measurement, display of readings and data transfer. The flexible desktop software concept enables the user to select which measurement value windows to display on the desktop. This can either be just a full screen display of lux measurement values or a matrix containing numerical and graphical display fields. Each desktop configuration can be saved for later use.

Software Development Kit
For self-programmers the S-SDK-BTS256-E Software Development Tool option is available. The SDK is compatible with Lab View from National Instruments, NET from Microsoft and C/C++. The SDKs simplify incorporation of the BTS256-E series meters into user based systems.

Available With A Powerful WiFi Interface
The BTS256-EF Light-Color-Spectral-Flicker Meter with WiFi comes with a powerful WiFi interface enables long distance wireless remote control of the light meter. What separates the BTS256-EF WiFi from the basic BTS256-E is its added ability to perform flicker measurements plus a WiFi interface enabling long distance wireless remote control of the light meter.

Who is the BTS256-EF Light-Color-Spectral-Flicker Meter Designed For?
For lighting manufacturers, architectural, display, transportation, entertainment and other lighting designers and engineers, field service personnel, health and safety officers requiring all of the features and functions of the BTS256-E plus the ability to detect and quantify flicker components.

Product Specifications
For product specifications and configurable options for the BTS256-EF, please visit the Gigahertz-Optik main website here.

To Order The BTS256-EF LED-Luxmeter, Call Us Today At 1-978-462-1818.
Practical Solutions To Real LED Measurement Problems

Here's The Problem:
You are a lighting manufacturer that needs light measurement instrumentation capable of light and color qualification of your new Solid State Lighting (SSL).

The instrument must be able to accurately analyze LED and traditional light sources for comparison purposes.

Some of your fixtures are large in size so an integrating sphere would be required to measure total luminous flux. But the integrating sphere solution is out of the question due to the high costs, space requirements and maintenance involved.

Anyway, since your sources are designed for area illumination, for quality control purposes, illuminance measurements are more applicable than total luminous flux measurements in lumens.

Correlated Color Temperature (CCT) is most important to you.

However, the meter should reliably provide absolute as well as other color parameters and spectral data.

Here Are The Requirements:
A simple to operate, accurate light and color meter that can measure any type of light source in the field or in the lab. It must be:

  • field portable
  • battery powered
  • easy to read display
  • allow full remote control by PC for storing data, producing reports & tech spec sheets
  • competitively priced since multiple units will be required by field service personnel or possible use by technical sales department.

Here's The Solution:
For complete color, spectral and absolute analysis of SSL and any other light source the BTS256-E LED Luxmeter is the right tool.

Compact, splashproof light meter with flicker measurement function for mobile use
Compact, splashproof light meter with flicker measurement function for mobile use


Socket for Tripod Mount
Socket with Tripod Thread

Hard-top case for safe transport and storage of the BTS256-E and its accessories
Hard-top case for safe transport and storage of the BTS256-E and accessories

Interested in discussing your light measurement application? Give us a call!