The color sensors of the SI-COLO3 and SI-COLO4 series operate with the 3-color-range method. As a light source they use pulsed white-light LEDs, the luminescence color sensors use UV LEDs. Modulation is done with 30 kHz or 100 kHz, respectively, and the lock-in-technology guarantees an extremely high insensitivity to outside light. A triple receiver for the RED, GREEN, and BLUE content of the light reflected from the target is used as a receiver. 

The SI-COLO3 color sensor can be "taught" up to 15 colors, whereas the SI-COLO4 color sensor can be "taught" up to 31 colors. Tolerances can be set for every taught color. In X/Y INT or s/i M mode the tolerances represent a color cylinder in space. In X/Y/INT or s/i/M mode the tolerance represents a color sphere in space. Color evaluation according to s/i M and s/i/M uses the Lab calculation method.
 

Information on the range of types
 
–d... (integrated optics with various light spot diameter sizes)
High-speed color detection of small objects

The color sensors of SI-COLO3-d… or SI-COLO4-d… series project a white-light spot with a diameter of approx. 1.5 mm to 50 mm (depends on sensor type) onto the object to be detected. The transmitter optics unit is located at the center of the receiver optics unit, which results in a highly compact design. This allows a high-precision and high-speed detection of small objects such as e.g. color markings or wires at a great distance.
 
–DIL (diffuse light with surface diffusor) 
Color inspection of structured and inhomogeneous surfaces
 
With many objects requiring color inspection an inhomogeneous surface causes problems in color determination. A structured surface, for example, leads to gloss rate fluctuations that cause difficulties for conventional color sensors because depending on the gloss rate the color is sometimes detected more intensively and sometimes less intensively.
The actual color is brightened or "softened" by direct reflection that depends on the respective gloss rate of the surface. With the color sensors of the SI-COLO-...-DIL series diffuse illumination considerably reduces this gloss effect. Furthermore, the large detection range allows an optical integration of structural fluctuations, and the color is thus reliably detected with great stability.
 
–FCL (focused light beam due by means of a clear glass plate) 
Reliable high-speed color detection at a large distance
 
The SI-COLO-...-FCL series allows the color differentiation of objects at a large distance. Depending on the version and on the object, a distance of up to 400 mm can be realised. Among others the FCL series features super-bright white-light LEDs. The sensors of this series ideally can be employed for distinguishing between glossy and non-glossy objects of the same color (e.g. objects without and with transparent foil).

–LUMI (with UV LEDs)
Quick color detection of fluorescent objects

With the luminescence color sensor SI-COLO-LUMI-30 series there is a sensor that apart from brightness differentiation (grey scale evaluation) also can perform color differentiation. The fluorescent objects can either be taught via the Windows® PC software SI-COLO3-Scope or via the push button that is integrated in the sensor or via the digital input IN0. 
 
–POL (polarised light by means of polarisation filter)
Color inspection of glossy objects

In practice, the reliable detection of the color of glossy objects usually is extremely difficult because the actual color information is mixed with direct reflection resulting from the gloss effect. Rich colors thus are turned into "soft" colors. The polarisation filters that are integrated in the SI-COLO-...-POL color sensor prevent such direct reflexion, the actual color thus can be clearly recognized and reliably detected.
Reflecting surfaces such as e.g. the high-gloss paints on automotive components can thus be clearly recognized.
 
–FIO (for use with fiber optics and optical frontend of the FIO series)
Color control even at difficult tasks through flexible integration
 
The FIO series is the color sensor series with the most flexible application possibilities. In addition to more than 50 different sensor head variants each for transmitted-light and reflected-light operation there also are nearly 70 optical frontends available. With the help of an external light source the dynamic range can be considerably increased. Due to the use of optical fibers this series also is well suited for use in Ex areas. 

Color measurement of self-luminous objects with the SI-COLO-..3-FIO:
In combination with a reflected-light optical fibre and a neutral-absorber attachment unit the SI-COLO-...-FIO makes it possible to perform color inspection of different self-luminous objects.