# US 5,349,181 A · Fiber optic chemical sensor having specific channel connecting design

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- Number: US 5,349,181 A
- Document ID: US5349181A
- Status: Granted
- Kind: A
- Application number: 08/098,125
- Filed: 1993-07-26
- Granted: 1994-09-20
- Earliest claimed: 1993-07-26
- Assignees: FCI - FiberChem, Inc.
- Inventors: Devinder P. Saini; Tommy J. Law
- Web page: https://patentgrep.com/patent/US5349181A

## CPC

- G01N 21/7703: {using reagent-clad optical fibres or optical waveguides (using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B)}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

In a sensor assembly, an optical fiber with a sensing region is connected at one end through a fiber guide tube to a detector housing containing a sensing detector. At the other end the fiber is connected through a fiber guide tube to a light source which has a reference detector mounted laterally thereto. The sensing and reference detectors are a matched pair of the same type. The guide tube in the source has a bevelled end which reflects a portion of light from the source to the reference detector.

## Claims

### Claim 1

A fiber optic chemical sensor, comprising:
an optical fiber having a sensing region formed on a portion thereof;
a sensing detector housing defining a channel therein;
a sensing detector mounted in said sensing detector housing channel;
a first fiber guide tube extending into said sensing detector housing and communicating with said channel formed therein; wherein one end of said fiber extends into said first tube and is optically aligned with said sensing detector;
a light source having a channel formed therein and a light emitting region aligned with said channel;
a second fiber guide tube extending into said source channel; wherein the opposed end of said fiber extends into said second tube and is optically aligned with said source;
a reference detector mounted laterally on said source for receiving a portion of light emitted from said source.

### Claim 2 (depends on 1)

The sensor of claim 1 wherein said second tube further comprises a bevelled end for reflecting said light from said source to said reference detector.

### Claim 3 (depends on 2)

The sensor of claim 2 wherein said bevelled end is formed at a 45.degree. angle to the tube axis.

### Claim 4 (depends on 1)

The sensor of claim 1 wherein said sensing and reference detectors are identical detectors.

### Claim 5 (depends on 1)

The sensor of claim 1 wherein said source further comprises an optically transparent integral housing defining said source channel.

### Claim 6 (depends on 1)

The sensor of claim 1 wherein said source is an LED and said sensing and reference detectors are photodiodes.

### Claim 7 (depends on 1)

The sensor of claim 1 wherein said sensing and reference detectors are matched photodiodes.

### Claim 8 (depends on 1)

The sensor of claim 1 wherein the end of said fiber which extends into said second tube is positioned at a distance from said light emitting region of said light source so that the outputs of said sensing and reference detectors have a preselected ratio.

### Claim 9 (depends on 1)

The sensor of claim 1 wherein said source further comprises an integral lens optically aligned with said light emitting region.

### Claim 10 (depends on 1)

The sensor of claim 1 further comprising an optical isolation layer formed on said sensing detector housing to optically isolate said sensing detector from external light sources.