Sensor Instruments
Entwicklungs- und Vertriebs GmbH
Schlinding 11
D-94169 Thurmansbang
Telefon +49 8544 9719-0
Telefax +49 8544 9719-13

High-frequency contrast sensors
SPECTRO-1 Series

High-frequency contrast sensors for UV, VIS and IR range

The SPECTRO-1 sensors are contrast sensors that are able to record even slightest brightness differences almost in real time. The sensor features analog and digital signal outputs. With the optical fibre types (FIO) inspection can be performed both in transmitted-light and in reflected-light mode.

The use of different light sources (apart from the white-light version, versions with UV, red, blue, and IR light source also are available) makes it possible to perform measurements starting in the UV range, in the visible range, and through to the IR range. Because of the wide type range object distances of up to approx. 1000 mm can be realised.
The sensor can be easily parameterised with the SPECTRO1-Scope Windows® PC software. The scope function that is integrated in the software makes it possible to watch the signal characteristic quasi in real time.
The contrast sensors of the SPECTRO-1 series can inspect both passive and active objects. With the software the sensor can be switched from passive to active objects. The sensor's analog output provides information about the current contrast value, while the digital output can be used to check whether the respective object lies in the permissible tolerance range.
SPECTRO-1 contrast sensors feature an impressively high scan frequency of 200 kHz.

Information on the range of types
Measuring principle SPECTRO-with SPECTRO1-Scope

Information on the range of types

–COF (confocal optics)

Transmitter and receiver optics are focused to the same distance.  The transmitter optics is integrated in the receiver optics, which allows a highly compact design. The -COF type especially is characterised by a small light spot size at a large distance, which means that even small objects can be reliably detected at a large distance ( < 1000mm ). In addition to the white-light types there also are versions that operate in the UV range (UV-A light is used at the transmitter side, and the visible wavelength range is evaluated at the receiver side;  -COF-UV types thus can be used for the inspection of fluorescent objects), and versions that operate with red laser light (-COF-LAS and -COF-LAS-CYL, which generate spot sizes in the tenth millimetre range at a large sensor distance and allow very narrow-band optical filtering).

–DIF (diffuse light with volume diffusor)

The light that is emitted by the transmitter LED is extremely diffused, which results in extreme gloss reduction. The sensor thus recognises a glossy black surface as black, and there is no gloss-related grey value shift towards higher values. 
–DIL (diffuse light with surface diffusor)

The objective is to reduce the gloss effect. Direct reflection has a disturbing effect on grey value determination (contrast), which means that glossy black surfaces also may be detected as grey, i.e. they may appear brighter than they normally are. Direct reflection can be reduced by using a surface diffusor, because the rate of diffuse transmitter light is increased.
–FCL (directed light with clear glass disk)

The transmitter LEDs are arranged in a ring. They converge with the narrow-band light cones at a distance that is defined by the sensor unit (with -50-FCL e.g. at 50 mm sensor distance from the object). Both diffusely and directly reflected light can reach the receiver optics, which means that a combined evaluation of grey value (contrast) and gloss is performed. For this sensor system a glossy black object thus differs from a dull black object. In addition to the white-light LED version there also is an IR type (860 nm) which, among others, can be used for dullness inspection. 
–POL (polarised light with polarisation filters)

The sensor system features a polarisation filter both at the transmitter and receiver side. The polarisation directions of the two filters are rotated by 90° with respect to each other, which means that light of the same polarisation direction cannot pass the receiver filter. Since the polarisation direction exclusively is changed by diffuse reflection and not by direct reflection, this sensor type is excellently suited for gloss suppression, but also for the detection of transparent plastic films (whose direction of rotation also can be detected), because such films also show a certain polarisation effect. 
–UV (with UV-LEDs)

With this sensor type the UV light that is emitted by the transmitter LEDs is partially converted into the visible wavelength range by fluorescent objects, and can then be detected at the receiver side. 
–FIO (for use with fiber optics and optical frontend of the FIO series)

An extensive selection of optical-fibre transmitted-light and reflected-light versions is available. In combination with the respective attachment optics spot sizes starting from a diameter of 0.2 mm with an object distance of 10 mm up to object distances of 500 mm and spot sizes of 50 mm can be realised in reflected-light operation, and transmitter-receiver distances of up to 2000 mm can be covered. In addition to a white-light LED version there also are versions that operate in the UV-A, blue, red, and IR wavelength range (dullness inspection with 860 nm).


Measuring principle SPECTRO-1
with SPECTRO1-Scope (Windows® PC software)
The sensors of the SPECTRO-1 series are of single-channel design, i.e. they acquire the analog signal that comes from a receiver and evaluate this signal. Various light sources such as white light, UV light, IR light, or a laser can be used as a transmitter. The receiver is correspondingly matched to the transmitter. The acquired analog signal is provided through a voltage output and a current output.
The software can be used to select various evaluation modes for the analog signal. The status of the analog signal is provided through 2 digital outputs in accordance with the selected evaluation mode. A digital input allows external "teaching" of the sensor. An additional input allows the "freezing" of the analog output signal upon a positive input edge.
The SPECTRO-1 sensor allows highly flexible signal acquisition. The sensor, for example, can be operated in alternating-light mode (AC mode), which means the sensor is not influenced by external light, or in constant-light mode (DC mode), which provides outstanding high-speed sensor operation. An OFF function deactivates the sensor's integrated light source and changes to DC mode, which allows the sensor to detect so-called "self-luminous objects". With the stepless adjustment of the integrated light source, the selectable gain of the receiver signal, and an INTEGRAL function the sensor can be adjusted to almost any surface or any "self-luminous object".
A micro-controller performs 12-bit analog/digital conversion of the analog signal, which allows recording and evaluation of the signal. Furthermore the SPECTRO-1 sensor offers various options for intelligent signal processing such as e.g. dirt accumulation compensation.
Parameters and measurement values can be exchanged between PC and sensor either through RS232 or Ethernet (using an Ethernet adaptor, e.g. SI-RS232/Ethernet-4-...). Through the interface all the parameters can be stored in the non-volatile EEPROM of the sensor.
The PC software facilitates the parameterisation, diagnostics, and adjustment of the sensor system (oscilloscope function). The software furthermore provides a data recorder function that automatically records data and stores them on the hard disk of the PC.
SPECTRO-1 sensors are temperature-compensated over a range of 0°C to 80°C.
Possible firmware updates can be easily performed through the RS232 interface, even with the sensor system in installed condition.
When parameterisation is finished, the color sensor continues to operate with the current parameters in STAND-ALONE mode without a PC. 


We exhibit:

25. Fakuma
October 17-21, 2017
Friedrichshafen, Germany

16. Expert Conference
Automotive Interior
November 8-9, 2017
Regensburg, Germany


New applications:
Application-News N° 627-629
  • Color differentiation between white and metallic white lacquered parts
  • Differentiation of a single-sided adhesive-coated front of a filter paper from the uncoated backside
  • Frontside - backside differentation of paper web

Software updates available:
• SPECTRO3-ANA-Scope V2.0


We welcome our new sales partner for Costa Rica, Panama, Nicaragua, Honduras, Guatemala, El Salvador, and Belize:


And we are pleased that we are now also represented in Peru, Ecuador, Venezuela and the Dominican Republic by our sales partner



New products:
Product-News N° 231-234

L-LAS-LT-SL Series
Top Speed Plus Pinpoint Accuracy.
Distance measurement with the compact laser triangulation sensors L-LAS-LT-SL.

More information soon ...

Measuring SPECTRO-3 color sensors with five digital outputs.
The color sensors of the SPECTRO-3-MSM-DIG series can be taught up to 31 colors that are provided directly at the outputs, and up to 64 colors that are output by means of grouping. For each of these taught colors it is possible to set tolerances. These types allow L*a*b* , L*u*v* , L*u'v' , x,y,Y , X,Y,Z and L*C*h* color measurement.


Trade fairs 2017:
Fakuma 2017, Friedrichshafen
sps ipc drives 2017, Nuremberg


New firmware available
(please ask if required)


New product range:
Individual Sensor Systems

Complete Solutions

SPECTRO-1 Series
Contrast sensors.
Two new sensor types with blue light or green light are available:

GLAST Series
Gloss and structure sensors.

SPECTRO-2 Series
2-channel sensor systems.
The SPECTRO-2‎ series now closes the gap between contrast sensors (SPECTRO-1 series) and color sensors (SPECTRO-3 series).

Inline Measuring Color Sensors with D65 Similar Optical Spectrum.


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