Detection device for hazardous materials

Abstract

A detection device that is activated by the interaction of a hazardous chcal with a coating interactive with said chemical on an optical fiber thereby reducing the amount of light passing through the fiber to a light detector. A combination of optical filters separates the light into a signal beam and a reference beam which after detection, appropriate amplification, and comparison with preset internal signals, activates an alarm means if a predetermined level of contaminant is observed.

We claim: 
     
       1. A hydrazine detection device comprising: a. a power supply interconnected to a light source;   b. sensor means interconnected with the light source and having an optical fiber coated with a material comprising polyethylene oxide and 4-nitrobenzaldehyde capable of reacting to the presence of hydrazine;   c. light detecting means; and   d. alarm means to indicate a change in light transmitted by the optical fiber responsive to the presence of a predetermined level of hydrazine.   
     
     
       2. The device as recited in claim 1, wherein the refractive index of the material coating the fiber optic cable is substantially similar to the refractive index of the cable. 
     
     
       3. The device as recited in claim 1, wherein the optical fiber is coated to a depth of less than one micron. 
     
     
       4. The device as recited in claim 1, wherein the material comprises 1% polyethylene oxide by weight and 99% methylene chloride by weight to which is added 4-nitrobenzaldehyde to make a 1×10 -4  molar solution. 
     
     
       5. The device as recited in claim 1, wherein the sensor means further comprises: a. a tungsten-halogen light;   b. a focusing lens; and   c. a first X-Y micrometer stage wherein the tungsten-halogen light is focused by the focusing lens into a first end of said optical fiber.   
     
     
       6. The device as recited in claim 5, wherein the light detecting means further comprises: a. a housing having: i. a dichroic mirror;   ii. a focusing lens;   iii. a second X-Y micrometer stage; and   iv. a first and second light filter;     b. a signal photodiode interconnected with a signal amplifier; and   c. a reference photodiode interconnected with a reference amplifier.   
     
     
       7. The device as recited in claim 6, wherein the first light filter is a beam-pass filter of about 360 nanometer wavelength and the second light filter is a beam-pass filter of about 700 nanometer wavelength.