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BTS2048-VL-F, CCD spectroradiometer with light guide input

The only difference between the BTS2048-VL-F and the BTS2048-VL is that the BTS2048-VL-F has a light guide input and therefore meets all the requirements of a high-end array spectroradiometer.

Flexible light guides are convenient for applications where the BTS2048-VL cannot be coupled directly to the input accessories required for the application. The BTS2048-VL-F has a mount to which the light guide can be attached easily using a 10 mm sleeve. Light guides of different lengths, diffusor windows for axial or 90° incident light and adapters for attachment of the light guide to an integrating sphere are among the accessories offered by Gigahertz-Optik. Customized light guides are also available on request.

 User software and developer software

The standard S-BTS2048 user software has a customizable user interface and a large number of display and function modules which can be activated when configuring the BTS2048-VL-F with the respective accessory components from Gigahertz-Optik GmbH. The S-SDK-BTS2048 developer software is offered for integration of the BTS2048-VL-F in the customer’s own software.


One essential quality feature of photometric devices is their precise and traceable calibration. The BTS2048-VL-F is calibrated by Gigahertz-Optik’s calibration laboratory that was accredited by DAkkS (D-K-15047-01-00) for the spectral responsivity and spectral irradiance according to ISO/IEC 17025. The calibration also included the corresponding accessory components. Every device is delivered with its respective calibration certificate.

The BTS2048-VL spectroradiometer for use with light guide
1) BTS2048-VL 2) BiTec sensor with Si photodiode, CCD array spectrometer 3) Filter wheel with OD1, OD2 and shutter 4) Light-guide mount 5) Light-guide Adapter 6) Light incident 7) Microprocessor for data procesing and communication 8) USB 2.0 Interface 9) High Speed ethernet Interface 10) Microprocessor CCD sensor control 11) Trigger In/Out 12) Microprocessor photodiode 13) DC voltage supply
CP-F16-M-10 light guide adapter
S-BTS2048 User software interface
Graphical view of the spectrum
CIE 1976 Chromaticity diagram
CRI Bar Plot
Short description

CCD spectroradiometer with light guide input for coupling the light meter from the application. Wide dynamic range for CW and pulsed measurements. Measurement parameters dependent on the optional accessory, spectrum, luminous color, and color rendering index

Main features

Compact device. BiTec detector with back-thinned CCD (2048 pixels, 2 nm optical resolution, electronic shutter) and Si-photodiode with V(lambda) filter. Optical bandwidth correction (CIE214). Filter wheel with shutter and two attenuation filters. Input lens for light guide

Measurement range

Depending on the accessories. Spectral range 280 nm to 1050 nm

typical applications

Separate setup of the CCD spectroradiometer and measurement optics. Measurement device with light guide for integration in test systems for front-end and back-end LED binning


Factory calibration. Traceable to international calibration standards

Measured Quantity

Spectral irradiance (W/(m² nm)), irradiance (W/m²), illuminance (lx), spectral radiant intensity (W/(sr nm)), radiant Intensity (W/sr), luminous intensity (cd), dominant wavelength, peak wavelength, center wavelength, centroid wavelength, x, y, u´, v´, X,Y,Z, delta uv, color temperature, color rendering index (CRI) Ra, R1-R15, TM-30-15, CQS, CIE-170, etc.. Option integrating sphere: in addition spectral flux (W/nm) and luminous flux (lm) Option goniometer: in addition radiant intensity (W/sr) distribution and luminous intensity (cd) distribution


With light guide and diffuser

Accuracy class B according to DIN 5032 and CIE No. 69
Accuracy class A for f1`, u, f3 and f4 according to DIN 5032 and CIE No. 69

Input optics

Light guide adapter F16-F

Filter wheel

4 positions (open, closed, OD1, OD2). Use for remote dark current measurement and dynamic range extension.


Parallel measurement with diode and array is possible, thereby linearity correction of the array through the diode and online correction of the spectral mismatch of the diode through a*(sz(λ)) respectively F*(sz(λ)).


Depending on the light guide

Spectral Detector
Integration Time

2 μs - 4 s        *1

spectral range

(280 -1050) nm

Optical Bandwidth

2 nm

Pixel resolution

~0.4 nm/Pixel

Number of pixels



Highly sensitive back-thinned CCD chip


16bit (25 ns instruction cycle time)

Peak wavelength

±0.2 nm

Dominant wavelength

±0.5 nm           *2

Δy Δx uncertainty

±0.0015 (Standard illuminant A)
±0.0020 (common LED)

Repeatability Δx and Δy



Standard illuminant A 30K; LED up to +/- 1.5 % depending of the LED spectrum

Band-pass correction

mathematical online band-pass correction is supported


completely linearized chip >99.6%

Stray Light

2E-4           *3

Base line noise

5 cts     *4


5000        *5

dynamic range

>9 Magnitudes

CRI (color rendering index)

Ra and R1 to R15

Integral Detector

Spectral responsivity with fine CIE photometric matching. Online correction of the photometric matching through spectral measurement data (spectral missmatch factor correction).

Measurement time

20 µs  - 6000 ms


rise time (10 – 90) %


50 µs


65 µs


1.5 ms

Measurement range

Nine (9) measurement ranges with transcendent offset correction

f1' (spectral mismatch)

≤6% (uncorrected)

≤1,5% (f1' a*(sz(λ)) respectively F*(sz(λ)) corrected by spectral data, done automatically by BTS technology)


32bit for device control,16bit for CCD array control, 8bit for photodiode control


USB V2.0, Ethernet (LAN UDP protocol), RS232, RS485

Data transfer

Standard for 2048 float array values via ethernet 7ms, via USB 2.0 140 ms

Input Interfaces

2x (0 - 25) VDC, 1x optocoupler isolated 5 V / 5 mA

Output Interfaces

2x open collector, max. 25 V, max. 500 mA


Trigger input incorporated (different options, rising/falling edge, delayed, etc.)


User software S-BTS2048
Optional software development kit S-SDK-BTS2048 for user software set-ups based on .dll‘s in C, C++,C# or in LabView.

Power Supply

With power supply: DC Input 5V (±10 %) at 700 mA
With USB bus (500mA) *8


103 mm x 107 mm x 52 mm (Length x Width x Height) + Fiber Adapter




Tripod and M6 screw threads

Front adapter UMPA-1.0-HL for use with integrating sphere port-frame UMPF-1.0-HL

temperature range

Storage: (-10 to 50) °C

Operation: (10 to 30) °C           *9


*1 It is recommended to perform a new dark signal measurement for every change in the integration time
*2 typical value, the uncertainty of the dominant wavelength depends on the spectral distribution of the LED
*3 typical value, measured 100nm left of the peak of a cold white broadband LED
*4 *5 typical value measured without averaging for a 4ms measurement time and full scale control of the array. Averaging results in quadratic rise of the S/N
i.e. quadratic fall of the base noise e.g. averaging to a factor 100 improves the S/N by a factor 10
*6 Minimum 500/1 S/N. Maximum at full scale control.
*7 Irradiation only allowed for a short time so as to avoid thermal damage
*8 during USB connection, not all functions are available due to the limited current supply e.g. no Ethernet
*9 Device required for temperature stabilization in approx. 25min. In measurement is performed in the warm-up phase, or if measurements are performed under varying temperatures, dark signal measurement is required for each measurement. At high temperatures and at the maximum integration time a decreased dynamic can be used.


Option: CP-CD-IL-10 or CP-CD-90-10 (Irradiance)
spectral irradiance responsivity range (spectral measurement)

(5E-5 - 3E5) W/(m²nm)

(Note: typically CP-CD-90-10 is 10% insensitive compared to this stated numbers of CP-CD-IL-10)

Illuminance measurement range (integral measurement)

(5E-1 - 1E9) lx

(Note: typically CP-CD-90-10 is 10% insensitive compared to this stated numbers of CP-CD-IL-10)

Type Description File-Type Download
Datasheet BTS2048-VL-F PDF
BTS2048 Series BTS2048 'Not just another spectrometer' brochure PDF
Produktname Product Image Description Show product
S-SDK-BTS2048 Software Development Kit for BTS2048 variants.
Article-Nr Modell Description Request / Compare
15298737 BTS2048-VL-F

Measuring device, hard cover box, users guide, S-BTS2048 software, calibration certificate.

15305452 CP-F16-M-10

Adapter for LG-1.5-10 light guides to lightmeters with F16-F mount.


15307119 CP-LG-1.5-10-2

Flexible light-guide with 1.5 mm Diameter fiber, 10 mm diameter mounts and 2 m length.


15305454 CP-CD-IL-10

Diffusor window adapter for LG-1.5-10 light-guides. 37 mm housing diameter.

15305453 CP-CD-90-10

90° diffusor window adapter for LG-1.5-10 light-guides. 37 mm housing diameter.

15298470 S-SDK-BTS2048

Software development kit with users guide.

15307925 S-T-RECAL-BTS2048

Software module for functional enhancement of S-BTS2048 software. Support of BTS2048 series light meter re-calibration via the user.

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