Fiber Sensors

Application and Data

(1) MSR (Mirror Surface Rejection) Function

[Principles]

This function and structure uses the characteristics of the Retroreflector and the polarizing filters built into the Retro-reflective Sensors to receive only the light reflected from the Retroreflector.

The waveform of the light transmitted through a polarizing filter in the emitter changes to polarization in a horizontal orientation.

The orientation of the light reflected from the triangular pyramids of the Retroreflector changes from horizontal to vertical.

This reflected light passes through a polarizing filter in the receiver to arrive at the receiver.

[Purpose]

This method enables stable detection of objects with a mirror-like surface.
Light reflected from these types of objects cannot pass through the polarizing filter on the receiver because the orientation of polarization is kept horizontal.

[Examples]

A sensing object with a rough, matte surface (example (2)) can be detected even without the MSR function. If the sensing object has a smooth, glossy surface on the other hand (example (3)), it cannot be detected with any kind of consistency without the MSR function.

[Caution]

Stable operation is often impossible when detecting objects with high gloss or objects covered with glossy film. If this occurs, install the Sensor so that it is at an angle off perpendicular to the sensing object.

(2) Technology for Detecting Transparent Objects Exhibiting Birefringence P-opaquing (Polarization-opaquing)

Conventional methods for detecting transparent objects depend on refraction due to the shape of the sensing objects or on the attenuation of light intensity caused by surface reflection. However, it is difficult to attain a sufficient level of excess gain with these methods. P-opaquing uses the birefringent (double refraction) property of transparent objects to dramatically increase the level of excess gain. The polarization component that is disturbed by the sensing object as they pass along the line is cut by a special and unique OMRON polarization filter. This greatly lowers the intensity of the light received to provide stable detection with simple sensitivity adjustment. "P-opaquing" is a word that was coined to refer to the process of applying polarization in order to opaque transparent objects that exhibit the property of birefringence.

Excellent detection performance with transparent films. (E32-LR11NP + E39-RP1)
The specially designed filter eliminates undesirable light, which allows significantly more light to be interrupted for stable detection of films.

(3) Influence of Fiber Cable Length

The sensing distance listed in the Fiber Units specifications are based on the fiber cable lengths found in the suffix of the model number.
The sensing distance will change if the fiber cable is cut or extended.
The following graph shows the percentage change of the various fiber cable length, where 100% is the sensing distance for a fiber cable with a length of 2 m.
Use this as a guideline for installation distances.
Keep in mind that extending the cable with a fiber connector will result in even shorter sensing distances than the value given in the graph.

* The 100% value is for a fiber cable with a length of 2 m (same for Through-beam and Reflective Models).

(4) Reflective Models: Sensing Distance Ratios by Workpiece Materials

The following graph shows the percentage change of the various workpieces, where 100% is the sensing distance for white paper, the standard sensing object.
Refer to the value of the material that looks like your workpiece.

* White paper is 100%.

(5) Surface Color and Light Source Reflectance

Surface Color Reflectance

Identifiable Color Marks

The numbers express the degree of margin (percentage of received light for typical examples).
Models with an RGB light source support all combinations.

Sensor light color	Product classification	Model
	Fiber Sensors	E3NX-FA
		E3X-HD
		E3X-SD
		E3X-NA
		E3X-MDA
	Fiber Sensors	E3X-DAB-S
	Fiber Sensors	E3X-DAG-S
	Fiber Sensors	E3X-DAC-S

(6) FAQs