What Is a Photoelectric Sensor Reflector? Types and Selection Criteria
A photoelectric sensor reflector is a passive optical part, usually built from corner-cube prisms, that returns the light of a retroreflective photoelectric sensor in the direction it came from.
A photoelectric sensor reflector is a passive optical part that returns the light sent by a retroreflective photoelectric sensor back in the direction it came from. It is mounted opposite the sensor with no electrical connection; when an object breaks the beam between them, the sensor output changes state. It is used for counting on conveyors and at door and barrier passages.
Its surface is usually made of small corner-cube (triple-prism) cells; it returns light in the direction it came from even when the light arrives at a slight angle. A mirror returns light to its source only at a right angle.
Note: In the Turkish catalog, "prizmatik" (prismatic) in a sensor's name describes its rectangular housing; it has nothing to do with the reflector's prism structure.
Types
- Square, rectangular and round plastic reflectors: Rigid types fixed with screws or adhesive.
- Large panel reflectors (such as A4 size): Preferred at long range because the light spot widens; they also make alignment easier.
- Adhesive strip reflectors: For narrow surfaces where a rigid reflector does not fit; they return less light, so the range is shorter.
Selection criteria
- Reference reflector: The maximum range in the sensor datasheet is measured with a specific reflector. If the sensor will work close to its limit, choose a reflector equal to or larger than that one.
- Polarizing filter: Polarized sensors tell shiny objects (metal cans, foil packaging) apart from the reflector because a corner-cube reflector rotates the light's polarization. Only a corner-cube reflector or micro-prism tape works with them.
- Mounting: The reflector must sit on the sensor's optical axis and roughly perpendicular to it.
- Object size: The object must fully break the beam; for small objects, check the minimum detectable object size in the datasheet.
Common mistakes
- Detecting shiny objects with a non-polarized sensor: The shiny surface reflects light like a reflector, so the object is not seen.
- Transparent objects: A standard sensor may not reliably detect clear bottles or stretch film; a transparent-object sensor is needed.
- Dirty reflector: Dust, oil mist, condensation or icing reduce the returned light; the sensor may act as if the beam is broken with no object present. Mount the reflector where it can be cleaned.
Products in the catalog
The Photoelectric Sensor Reflectors category lists 7 active reflectors from Isıso (October 2026):
| Shape | Size | Model |
|---|---|---|
| Square | 30 mm | RD30 |
| Square | 50 x 50 mm | RL50 |
| Square | 100 x 100 mm | RD100 |
| Rectangular | 40 x 60 mm | RL40 |
| Round | 80 mm diameter | RD80 |
| A4 size | 210 x 290 mm | R210290 |
| Adhesive strip | 50 x 1000 mm | R501000 |
The product pages do not state polarized compatibility; confirm it before ordering for a polarized model. Sensors that work with a reflector are listed mainly under Retroreflective Rectangular Photoelectric Sensors (Lanbao and Isıso, 22 products; 5 Lanbao models are polarized) and Cylindrical Photoelectric Sensors; some retroreflective Lanbao models are in Plastic-Body Rectangular Photoelectric Sensors. Where a reflector cannot be mounted, Through-Beam Rectangular Photoelectric Sensors with separate emitter and receiver can be used.
Frequently asked questions
Does reflector size affect the sensing range?
Yes. The datasheet range is measured with a specific reference reflector; it is shorter with a smaller or strip reflector.
Does every reflector work with a polarized sensor?
No. Only a corner-cube (prismatic) reflector or micro-prism tape works. Mirrors and glass-bead tape do not rotate the polarization, so the sensor does not see them.
What is the difference between a retroreflective and a through-beam sensor?
In a retroreflective sensor the emitter and receiver share one housing and an unwired reflector goes opposite. In a through-beam sensor both separate housings need cabling; it usually works over longer distances and copes better with dirt.