The
Assemblies category consist of a variety of products that can be
used in many non-contact sensing situations. Optoelectronic assemblies
typically consist of an optical transmitting device and a sensing
device. The optical transmitting device can be either an IRLED
or VCSEL with a sensing device consisting of a Photodiode, or Phototransistor,
or Photodarligton, or Photologic® device. The optical pair (transmitter
and sensor) is mounted in either a reflective, slotted or transmissive
configuration.
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Reflective
assemblies consist of a transmitting and sensing
device that are designed to recognize the presence or
absence of a infrared reflective surface. The reflective
assembly is designed in either a focused or non-focused
configuration.
Focused devices are designed to have the IRLED or
VCSEL, optical transmitter and Photodiode, Phototransistor,
Photodarlington or Photologic®,
optical sensor, pointing to the same spot at a specified
distance in front of the
device
package. This design enhances that ability of a infrared
surface at or about the specified distance to reflect a
sufficient signal, form the IRLED or VCSEL, allowing the
optical sensor,
Photodiode, Phototransistor, Photodarlington or Photologic®,
to provide enough signal allowing the following electrical
circuitry to acknowledge the reflective signal change.
As the
reflective surface gets further away from the front of
the device, the signal that is reflected is reduced thus
not
allowing the sensor to recognize it’s presence. The
use of an LED Transmitter and Optical Sensor provide a
designed that
widens the depth of field even for focused assemblies.
The use of a VCSEL (Vertical Cavity Surface Emitting Laser)
has
a tight area of light emission thus making the focused
distance more critical than with a LED. The VCSEL also
has a higher
light intensity thus making it easier for the Optical sensor
to recognize the presence of a reflecting surface.
Non-Focused packages
are designs where the IRLED or VCSEL, optical transmitter,
is configured to radiate in a pattern parallel to the optical
sensor, (Photodiode, Phototransistor, Photodarlington or
Photologic®)
device. These devices can be used to recognize objects
in a wider variety of distances from the emitting
and sensing devices. The VCSEL provides a high intensity,
narrow beam angle infrared spot thus allowing a greater
variation of reflective materials and making it easier
for the optical sensor to recognize the presence or absence
of a target.
- Slotted
or Transmissive assemblies are configured with
the optical transmitter (IRLED or VCSEL) on one side
of the air gap and the optical sensor (Photodiode, Phototransistor,
Photodarlington, Photologic®)
on the other side. As an opaque object to infrared
light moves between the IRLED
or VCSEL, the output of the optical sensor (Photodiode,
Phototransistor, Photodarlington, Photologic®)
changes to the opposite state allowing subsequent
electronics
to recognize the change. The distance between the
optical transmitter and optical sensor can vary
from 2 mm (0.080
inches) to greater than 1 m (39 inches). When special
timing circuits are used, the distance between
the optical transmitter and the optical sensor
can be increased significantly
and subsequently assist in the reduction of ambient
infrared or sun light.
- Optoisolators are
devices designed to isolate electrical energy between two
circuits. They are typically sealed packages consisting
of an optical transmitter (IRLED or VCSEL) on one side
and an optical sensor (photodiode, phototransistor, photodarlington,
photologic®)
on the other side. Optoisolators are designed for
applications that require voltage isolations from
voltages
of 1,000 voltages or greater. They can be used for
any lower voltage requirement without concern and
come in a
variety of package configurations from a simple cube
design to a round tube. A slotted or transmissive
device can be
used as an optoisolator as long as the slot is protected
from any opaque material restricting the optical
light beam.
- Matched
Pairs consist of an optical transmitter (LED
or VCSEL) and optical sensor (Photodiode, Phototransistor,
Photodarlington, Photologic®)
matched to meet specific needs.
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