BTS256-E Light-Color-Spectral Meter

A State-of-the-Art LED Illuminance Color Spectral Meter
That Accurately Measures SSL as well as Traditional Light Sources

BTS256-E-LED Luxmeter for LED Measuremnt from Gigahertz-Optic

An Innovative New Lightmeter Designed Specifically For Solid State Lighting (SSL), CFL, Traditional Lamps & Displays

Replaces Visual Inspection With Precise Data

It's Not Your Traditional Illuminance Meter

Fully Characterizes Any Type Of Light Source For Precise Quality Control
Gigahertz-Optik's new BTS256-E Light-Color-Spectral Meter provides all necessary illuminance (photopic & scotopic), color and spectral data to fully qualify SSL, CFL and any other type light source. Its Bi-Technology sensor improves measurement accuracy and is precisely cosine corrected.

Fourteen Different Measurement Capabilities
BTS256E LED Luxmeter video

  • Ep photopic illuminance
  • Es scotopic illuminance
  • Es/Ep ratio of scotopic and photopic illuminance
  • EVE “Equivalent Visual Efficiency” factor
  • Ee irradiance
  • Eλ spectral irradiance
  • x, y CIE 1931 color coordinates
  • u‘, v‘ CIE 1976 color coordinates
  • CT color temperature
  • Δuv deviation from the blackbody locus
  • λdom dominant wavelength
  • λp peak intensity wavelength
  • λ0,5 spectral half-width
  • CRI Ra and R1 to R15 color rendering index

Customizable Display of Readings
The BTS256-E´s high resolution display enables the user to choose between 11 standard measurement display configurations as well as five extra user customizable ones. Switching between the different displays is easy using the three front panel buttons. An additional Info-Display shows the measurement parameters currently under use.

Accurate Measurements with Bi-Technology Sensor
The BTS256-E meter is equipped with Gigahertz-Optik´s BTS256 Bi-Technology light sensor which includes both a photometric photodiode and diode array. Any spectral mismatch error of the photopic sensor is compensated on-line using the diode array's measured spectral data. This reduces measurement uncertainty when evaluating any type of light source.

Photometrically Corrected Filtered Photodiode Light Detector
The traditional light detector employing a silicon diode and a photometric correction filter still provides 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 equipped with a second diode array detector that works with the filtered photodiode detector.

256 Pixel Diode Array Spectroradiometer
The BTS256 light sensor´s CMOS diode array provides precise luminous spectral measurement data. The spectral data is used for luminous color value and scotopic illuminance calculations.

Automatic Dark Signal Adjustment
On-line dark signal compensation dependent on the measurement time is accomplished by means of an electronic shutter located in front of the Bi-Tech Sensor enabling an optimum signal-to-noise ratio.

On-Line Complementary Use of Measured Data
On-line measured data from each detector is used in a complementary method to enhance the overall measurement quality. The filtered photodiode‘s measurement values are used to improve the linearity of the diode array whereas the diode array‘s spectral data is used to correct for any spectral mismatch error of the filtered photodiode. This is essence of the Gigahertz-Optik  Bi-Technology Sensor and what sets it apart from other light meters.

Modulated Light Measurement (PWM)
Pulse width modulated (PWM) light characterized by short pulses and varying pulse intervals requires the device's measurement rate to be synchronized with the modulation frequency. The BTS256-E measures the light's modulation frequency with its fast filtered photodiode and the measurement rate is synchronized automatically.

Cosine Spatial Response
A basic requirement for accurate illuminance measurement is a precise cosine corrected measurement geometry (field-of-view).  This light detector spatial response allows light from different angles of incidence, such as in general and street lighting, to be angularly weighted correctly in the measurement. Despite its large 20mm large diameter the BTS256-E cosine correction corresponds to DIN 5036 Quality Class B with f2 ≤ 3%.

Easy Operation
Using the BTS256-E is easy thanks to three function key operation and logical menu navigation. In standard measurement mode the meter automatically sets up and is ready to go. In expert mode the experienced user has access to all measurement parameters.

Many Extra Useful Functions & Features

  • Time delay measurement allows user time to get out of the field of view when performing the measurement
  • The display can be automatically switched off during the measurement
  • End of measurement signal tone option
  • Illuminance distribution mapping using a computer generated layout with grids for single measurements. The measurement points can be sequentially executed and saved.
  • Fast data logger measurement mode that allows clocked reading taking from the photodiode with a measurement rate of up to a maximum of 100ms
  • Second data logger measurement mode that enables the clocked recording of all measured quantities including spectral measurement data
  • Date and time (real time clock) can be set
  • Tripod mount socket
  • Protective cap on detector

Use without PC
The BTS256-E is equipped with all the functions necessary for computer-independent use of the device. The rechargeable batteries offer 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

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 into user based systems.

Who is the BTS256-E Light-Color-Spectral Meter Designed For?
This innovative yet affordable new lightmeter is ideal for lighting manufacturers just starting up in SSL and LED replacement lamps as a quality control production tool and as a lab level instrument for design work. Architectural, display, transportation, entertainment and other lighting designers and engineers, field service personnel, health and safety officers will find it a highly useable field service meter.

Adobe Reader

Download the BTS256-E LED-Luxmeter Technical Data Sheet pdf file
(23 mb).

To Order The BTS256-E LED-Luxmeter, Call Us Today At 1-978-462-1818.


Lightmeter DIN class B (DIN 5032 part 7)
DIN class A for f1´, u, f3 and f4 (DIN 5032 part 7)
Light sensor Bi-Technology Sensor with a photodiode broadband sensor and a 256 pixel CMOS diode-array. Integrated aperture for automatic dark signal adjustment.
Input optic Diffuser window with 20mm diameter, cosine corrected field of view, F2 Error ≤3%
Broadband Sensor Silicon photodiode with photometric correction filter f1≤6% (f1 A(z) korrigiert ≤3%). Transimpedance amplifier with adjustable integration time (from 100μs to 6s). Seven(7) measurement ranges with offset correction. 16 Bit ADC.
Maximum measurable illuminance value ≥199,999 lx
Noise equivalent illuminance value ≤ 0.01lx
Calibration uncertainty of photopic Illuminance +/-2.2%
Spectral Sensor CMOS diode-array spectral radiometer. Spectral range from 380 to 750nm. Pixel resolution 1.5nm. Optical resolution 10nm.
5.2ms to 30s integration time, manual or automatic control.
Automatic shutter for dark signal measurements with an integration time similar to that of the bright measurement. Shutter on/off response time 100ms
Measurement time by 199,999 lx ≤ 5ms (white light)
Measurement time by 100 lx ≤ 1s (white light)
Scotopic measurement range spectral 1 to >199999 lx
Calibration uncertainty of scotopic Illuminance +/-2.2%
Color measurement range spectral 1 to >199999 lx
Peak wavelength: +/- 1nm
Dominant wavelength: +/- 1nm
Δx, Δy reproduce: Standard illuminant A +/-0.0001, LEDs +/- 0.0002 at 2000cts peak output
Δx, Δy uncertainty : Standard illuminant A +/-0.002, LED +/- 0.004
CCT Measurement range: 1700 to 17000 K
ΔCCT: Standard illuminant A 50K; LED to +/- 4% depending on the LED Spectrum
Color rendering index Ra and R1 to R15
Microprocessor 16Bit, 25ns instruction cycle time
Charging voltage 5VDC, 450mA per USB
Interface USB2; Mini USB Port
Temperature Operation: -10 to +30°C, Storage: -10 to +50°C
160 x 85 x 60mm (LBH)
Transport case Plastic hard-top casing, 333 x 280 x 70mm, 650g
BTS256E min and max measurable spectral irradiance
Practical Solutions To Real Application 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.

Standard Configuration Display
Standard Configuration Display

User Configured Display
User Configured Display

Ratio of Scotopic and Photopic Illuminance with EVE Factor (IES TM-24-13)
Ratio of Scotopic and Photopic Illuminance with EVE Factor (IES TM-24-13)

Spectral Illuminance and Irradiance

Photopic and Scotopic Illuminance

Color Coordinates

Coloring Rendering Index and Tristimulus Values

Information Display Showing Meter Parameter Settings n Included with Measurement Data File
Information Display Showing Meter Parameter Settings n Included with Measurement Data File

Socket for Tripod Mount
Socket for Tripod Mount

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 its accessories

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