Multi-channel optical fiber connector

Methods and apparatuses for securely aligning a plurality of optical fiber pairs, including a connection device with a body having recesses therein for a fiber guide to which are mounted a plurality of optical fibers, a removable connector to which are mounted a corresponding plurality of fibers, and a movable locking member disposed in the body and which positively holds the connector in the body so that ends of pairs of fibers are aligned and the connector is securely disposed in the body; and a sensing system with a base unit and optical fibers which employs such a connection device.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
This invention is directed to devices using optical fibers and to 
connectors for such fibers. In certain particular aspects this invention 
is directed to a connector which provides an aligned and stable interface 
for a plurality of optical fibers. 
2. Description Of Related Art 
An optical signal, e.g. a change in a light ray, conveyed by an optical 
fiber is an analog (as opposed to a digital) signal. The intensity, 
amplitude, phase, frequency, pulse width, time of flight, polarization, 
and wavelength of the light may vary. 
Various instruments use optical fibers and sensing materials. Due to 
environmental changes (e.g. changes in heat, pressure, humidity, etc.) or 
changes upon contact by certain chemicals, a change is effected in the 
sensing materials which effects a change in light passing through the 
sensing materials. For these instruments to produce accurate measurements, 
i.e. accurate indications of the change, the transmitted light signal 
should be as unaffected as possible by extraneous influences, particularly 
over long periods of time. Stability problems are encountered with certain 
prior art male-female connectors, particularly when frequent plugging and 
unplugging are required. Also, it is possible for such connectors to be 
plugged together with the fiber ends somewhat laterally or longitudinally 
displaced, or non-parallel with respect to each other; at an undesired 
distance apart; or with their ends rotated with respect to each other at 
an undesired angle. Various prior art devices require mating ferrules or 
similar apparatus. 
With certain prior art devices an optical fiber sensor interfaces with some 
type of near or remote controlling and/or monitoring and/or recording base 
system. In the past the fiber-fiber interface has lacked stability; i.e., 
due to the structure of items such as optical fiber mounts and connectors, 
the fibers have been permitted some degree of freedom of movement or have 
become skewed in position, resulting in an alteration and degradation of 
the light ray optical signal being transmitted by the fiber. When the 
signal conveyed is digital rather than analog, fiber-fiber interface 
stability is less of a problem. In highly sensitive analog measurements, 
however, e.g. the measurement of the concentration level of blood gases, 
even a minimal amount of mount or connector instability can result in 
degraded or useless measurements. 
There has long been a need for a device which provides a stable fiber-fiber 
interface for optical fibers. There has long been a need for a stable 
two-part optical-fiber connector. There has long been a need for such a 
connector which can be used with two or more pairs of interfacing optical 
fibers. There has long been a need for an optical fiber connector which 
insures that fiber ends are disposed adjacent each other in a desired 
relative disposition, and in a desired proximity. 
SUMMARY OF THE PRESENT INVENTION 
The present invention teaches a connector for a plurality of optical 
fibers; for example, but not limited to, a connector for blood sensing 
system for measuring blood parameters which employs two or more optical 
fiber sensors which extend to one part of a connector which is secured to 
a second part of the connector, the second part of the connector having 
corresponding fibers extending to a base unit. In one embodiment a device 
according to this invention has: an integrated multi-fiber connector; a 
receptacle body for receiving and releasably holding the connector; and a 
fiber guide mounted in the receptacle body. Sensing fibers extends from 
the connector for sensing, e.g. for sensing blood parameters. Transmission 
fibers extend from the fiber guide to a base unit which monitors and/or 
measures signals from the sensing fibers transmitted through the 
transmission fibers. The fiber guide is secured in the receptacle body so 
that the transmission fibers are maintained substantially in position 
within the receptacle body. The integrated multi-fiber connector is 
securely held in place within the receptacle body so that the sensing 
fibers are aligned with the transmission fibers. 
In one embodiment, stability of the connector with respect to the 
receptacle body and alignment of the fibers are achieved by providing a 
locking surface on the connector and a corresponding locking surface on a 
lock member. The lock member is movably mounted in the receptacle body and 
moves out of the way to permit entry of the connector into a receptacle 
body; then, by spring urging, the lock surface on the lock member moves 
against the lock surface on the connector to hold the connector in place. 
Preferably, the lock surfaces are configured and disposed so that the lock 
member lock surface urges the connector in three directions (e.g. along 
orthogonal x, y, z axes) to maintain the connector's position in a desired 
relationship with respect to the fiber guide so that the fibers of the 
guide and those of the connector are aligned. Stop members assure that the 
lock member moves the connector only a desired distance to a desired final 
location within the receptacle body. In the embodiment in which the lock 
member moves the connector in three directions, three stop arrangements 
are provided, one corresponding to each direction of movement. Precise 
positioning of the stop members and precise machining and configuration of 
the device components results in stability and in desired fiber alignment, 
thereby enhancing transmission of signals conveyed through the fibers. 
In one embodiment a multi-fiber connector assembly according to this 
invention for interfacing a plurality of optical fibers in aligned pairs 
to facilitate the transmission of signals therethrough has a receptacle 
body with a connector recess therein, a fiber guide recess therein, and a 
locking member recess therein; a fiber guide secured in the fiber guide 
recess with a plurality o transmission optical fibers mounted thereto; a 
connector body removably securable in the connector recess with a 
plurality of sensing optical fibers mounted thereto; and a locking member 
movably mounted in the locking recess and movable to contact and urge the 
connector body into a position in the connector recess so that each of the 
sensing fibers is paired adjacent one of the transmission fibers and 
adjacent ends of each fiber pair are aligned for signal transmission 
therethrough. 
In one embodiment of the present invention a sensing system employing fiber 
optics as sensing elements is provided which has a base unit for 
controlling light sent through the fiber optics and for monitoring light 
received through the fiber optics; transmission fiber optics extending 
from the base unit to a connector assembly; sensing fiber optics extending 
from the connector assembly to a sensor device; and the connector assembly 
has a multi-fiber connector assembly for interfacing a plurality of 
optical fibers in aligned pairs to facilitate the transmission of signals 
therethrough, the connector assembly having a receptacle body having a 
connector recess therein, a fiber guide recess therein, and a locking 
member recess therein, a fiber guide secured in the fiber guide recess 
with a plurality of transmission optical fibers mounted thereto, a 
connector body removably securable in the connector recess with a 
plurality of sensing optical fibers mounted thereto, and a locking member 
movably mounted in the locking recess and movable to contact and urge the 
connector body into a position in the connector recess so that each of the 
sensing fibers is paired adjacent one of the transmission fibers and 
adjacent ends of each fiber pair are aligned for signal transmission 
therethrough. 
In one embodiment the fiber guide and the connector are molded or machined 
parts with precise grooves into which the fibers are positioned and then 
glued so that no fiber mounting devices such as ferrules are needed. 
With appropriate positioning of the lock member, inadvertent removal of the 
connector from the receptacle body is prevented. 
It is, therefore, an object of at least certain preferred embodiments of 
the present invention to provide new, useful, unique, efficient, and 
effective devices and methods for interfacing corresponding optical 
fibers. 
Another object of at least certain preferred embodiments of the present 
invention is the provision of such devices and methods for connectors 
between fibers which are part of an optical sensor apparatus and fibers 
which extend to a base unit. 
Yet another object of at least certain preferred embodiments of the present 
invention is the provision of such methods and devices in which the 
sensing fibers are mounted in a first member and the transmission fibers 
are mounted in a second member and the two members are secured with 
stability and so that the fibers are aligned for good signal transmission. 
An additional object of at least certain preferred embodiments of the 
present invention is to provide such devices in which fibers are mounted 
in precise grooves without the need for mounting apparatuses. 
Another object of the present invention is the provision of such devices 
which can, in certain preferred embodiments, be miniaturized as compared 
to existing devices which employ separate mounting ferrules. 
Yet another object of the present invention is the provision of such 
devices whose cost, in certain preferred embodiments, is greatly reduced 
when the parts are molded of plastic with little or no additional 
machining required; thus, resulting in parts which can be disposable. 
The present invention recognizes and addresses the previously-mentioned 
long-felt needs and provides a satisfactory meeting of those needs in its 
various possible embodiments. To one of skill in this art who has the 
benefits of this invention's teachings and disclosures, other and further 
objects and advantages will be clear, as well as others inherent therein, 
from the following description of presently-preferred embodiments, given 
for the purpose of disclosure, when taken in conjunction with the 
accompanying drawings. Although these descriptions are detailed to insure 
adequacy and aid understanding, this is not intended to prejudice that 
purpose of a patent which is to claim an invention no matter how others 
may later disguise it by variations in form or additions of further 
improvements.

DESCRIPTION OF EMBODIMENTS PREFERRED 
Referring now to FIG. 1, a system 10 according to the present invention 
includes a receptacle 12 from which a transmission optical fiber or fibers 
14 extend to a base unit 13 and a connector 18 removably securable in the 
receptacle 12 and from which extend a sensing fiber element or elements 20 
to a device 22, e.g. an arterial cannula for insertion in vivo into an 
artery. As shown in FIG. 2A, the transmission fibers 14 extend to and are 
mounted in a fiber guide 24 which is fixed (e.g. by glue) in a fiber guide 
recess 26 (see FIG. 2B) in a lower body 28 of the receptacle 12. The 
connector 18 is removably disposed adjacent the fiber guide 24 in a 
connector recess 30 in the lower body 28. For clarity in FIG. 2A the fiber 
guide 24 and the connector 18 are shown spaced apart although in operation 
their final positions are such that they are very close together a set 
small precise distance apart, or in contact, with pairs of fiber ends 
aligned for signal transmission. The fibers 14 are surrounded by a harness 
or tubing 32 and the fibers 20 are surrounded by a harness or tubing 34. 
As shown in FIG. 2A, each fiber 14 is mounted in a groove 38 in the fiber 
guide 24, preferably held in place with epoxy and a lid 42 is secured over 
the fiber guide 24 with screws (see screws 23, FIG. 2C) extending through 
recesses 44 in the lid 42 and into holes 46 in the fiber guide 24. 
Also as shown in FIG. 2A, the connector 18 has grooves 48 in each of which 
are mounted one of the sensing element fibers 20 which are, preferably, 
held in place with epoxy. The connector 18 includes a connector body 50 
and a connector lid 52 which has a protruding portion 54 received and held 
in a recess 56 in the body 50. A ridge 58 extends upwardly from the top of 
the lid 52 and has a locking surface 60 for coaction with a locking member 
64 (FIG. 2C). Transmission fibers are, preferably, larger in diameter than 
sensing fibers. 
FIG. 2B shows the receptacle lower body 28 and an upper body 29 with a 
locking member recess 62. A locking member 64 is disposed in the recess 
62. A spring 66 urges the locking member 64 out of the recess 62 and a 
stop 65 coacting with walls of a hole 57 prevents the locking member 64 
from completely exiting the body 29. The locking member 64 has a locking 
member surface 68 which co-acts with the locking surface 60 of the lid 52. 
The disposition, configuration, and co-action of the surfaces 60 and 68 
results, preferably, in the urging of the connector 18 in three orthogonal 
directions within the receptacle 12. Movement in these three directions is 
restricted as desired by stop member 72, stops 74, and stops 76. The stops 
74 are preferably threaded bolts which are threadedly received in holes 47 
in the lower receptacle body part 29. When the connector 18 is in place in 
the receptacle 12, coaction of the locking member 64 and the ridge 58 
pushes the connector 18 against the stops 74. Thus, positioning of the 
stops 74 as desired insures the position, in one axis, of the connector 
18. Similarly, holes 43 (FIGS. 2B, 2D, 5) receive stop members 76 and the 
downward movement (as viewed in FIG. 2B) of the connector 18 is limited by 
the three stops 76. By providing three stops 76, tilting of the connector 
18 is prevented. The stop member 72 is disposed in a hole 86 in the fiber 
guide 24 (see FIGS. 2C and 8A) and insures that a desired gap is 
maintained between the fiber guide 24 and the connector 18 (in those 
embodiments in which a gap is desired). 
FIG. 3 shows the upper body 29 of the receptacle 12 having grooves 31 
through which may pass bolts or screws for attachment to a harness. The 
ridge 58 of the connector 18 is received in and movable in a track recess 
67. 
FIGS. 4A-4D show a locking member 64 with its angled locking surface 68 and 
a recess 71 into which an end of the spring 66 is inserted. In the 
embodiment shown, the surface 68 is angled 30 degrees from the top edge of 
the locking member 64 as shown in FIG. 4C and 45 degrees from the side 
edge as shown in FIG. 4D. 
FIG. 5 shows a lower body 28 of the receptacle 12 having grooves 51 (like 
the grooves 31 of the upper body 29, FIG. 3) for facilitating the mounting 
of the receptacle to a harness or tubing. Recesses 53 may be used to 
receive and hold an end of a tension yarn (not shown) used in fiber optic 
cables. Screws or bolts 97 extend through holes 96 (FIG. 3) in the upper 
body 29 and through holes 98 in the lower body 28 to secure the two body 
pieces together. 
FIGS. 6A-6D show the lid 52 for the connector 18 (as shown in FIG. 2A). In 
the embodiment shown in FIGS. 6A-6D, the locking surface 60 is angled 30 
degrees from a centerline A as shown and 45 degrees from a normal line B 
as shown to correspond to the locking member surface 68 of the locking 
member 64. This dual angling of the surfaces 60 and 68 provides for the 
pushing or urging of the connector lid in three orthogonal axes until 
appropriate stops are contacted to position the connector and fiber guide 
with respect to each other, thereby positioning pairs of optical fibers in 
substantial alignment. Although such urging in three directions is most 
preferred, urging in one or two directions is within the scope of this 
invention. 
FIGS. 7A and 7B show the body 50 of the connector 18 having an entry hole 
82 for a tubing or harness, a widened recess 83 for receiving an enlarged 
part (not shown) of a tubing or harness, and a fan-out recess 84 in which 
fibers fan-out from an end of a harness or tubing and extend to the 
grooves 48. 
FIGS. 8A-8C show the fiber guide 24 and its grooves 38 for receiving and 
holding fibers. The stop member 72 extends through a hole 86 in the fiber 
guide 24. The fiber guide 24 is held in place in the recess 26 (see FIGS. 
2B, 2C) by screws 27 (see FIG. 2C) extending through holes 21 in the fiber 
guide 24. 
FIG. 9 shows a typical stop member 81. Each of the stops 72, 74, 76 is, 
preferably, like stop member 81. 
Typical optical fibers useful with devices according to this invention are 
about 125 microns in diameter and typical grooves in fiber guides and 
connector bodies are between 5 and 6 mils. Fibers are, preferably, 
polished for optical clarity. By, preferably, potting the fibers in their 
grooves, e.g. with epoxy, no ferrules, O-rings or connectors (e.g. screws 
or bolts) are needed. 
In conclusion, therefore, it is seen that the present invention and the 
embodiments disclosed herein are well adapted to carry out the objectives 
and obtain the ends set forth at the outset. Certain changes can be made 
in the method and apparatus without departing from the spirit and the 
scope of this invention. It is realized that changes are possible and it 
is further intended that each element or step recited in any of the 
following claims is to be understood as referring to all equivalent 
elements or steps for accomplishing substantially the same results in 
substantially the same or equivalent manner. It is intended to cover the 
invention broadly in whatever form its principles may be utilized. The 
present invention is, therefore, well adapted to carry out the objects and 
obtain the ends and advantages mentioned, as well as others inherent 
therein.