APPARATUS AND METHOD FOR CHEMICAL AND BIOLOGICAL AGENT SENSING BACKGROUND Field of the Invention The invention relates to a sensor apparatus and a set of methods used to detect biological agents and chemical compounds using optical methods. The sensing apparatus consists of several electrical and optical elements including a tunable laser, a photodetector, a digital controller and a wireless transmitter. The methods consist of several processes needed to control the sensor including laser wavelength tuning, photodetector control, data conditioning and transmission protocol software.

Description of the Related Art A typical approach used to detect agents or chemicals uses Laser Induced Breakdown Spectroscopy (LIBS). High power laser light is applied to the sample, which is then vaporized into plasma. As the sample is vaporized a broadband spectrum of light is emitted due to multiple electronic transitions. The light is then sent to an optical spectrum analyzer that in turn determines the profile of wavelength versus intensity for the sample analyzed. The spectrum data is then processed by means of digital signal processing (DSP) in a computer in order to filter out noise in the spectrum. Finally, the resultant filtered spectrum is compared with a database of signatures for known biological and chemical agents. Some disadvantages of the LIES approach are : 1. LIBS destroys the sample in the analysis process since it turns it into plasma.

2. Because of the sample destruction the resulting spectrum corresponds to the elements that are part of the sample and not necessarily to the complex molecules that generally form part of an organic molecule.

3. The broad spectrum obtained has a substantial amount of noise because electronic transitions of many atomic energy levels are generated simultaneously. The broad an noisy spectrum requires a significant amount of digital signal processing in order to determine the various chemical compounds present. This situation reduces the reliability of the data obtained.

4. Because of the significant level of DSP and the large signature database required, a computer with significant processing power and memory is needed.

This increased the size of the package and requires large batteries to carry the sensor.

Figure 1 (100) illustrates the present methods for sensing agents. The method shown includes the LIBS approach as well as other approaches, which include infrared lighting techniques. A broadband light source (101) is used to generate a light beam (102) and apply light to the unknown agent (103). The materials in the unknown agent (103) absorb the light and in turn react by putting out emitted light (104), which is detected by a detector (105) consisting of an optical spectrum analyzer. The problem with the method is that the emitted light (104) has a wide spectrum (106), which is broadband in nature and also contains a substantial amount of noise because the broadband light source (101) produces electronic transitions in multiple shells in the atoms of the sample at once.

Figure 2 (200) illustrates an apparatus used to sense the unknown agent (103).

The light source (101) and detector (105) are used to capture a wide spectrum

(106) from the unknown agent (103). The apparatus contains batteries and a power supply (201). In addition, once the wide spectrum (106) has been obtained, there is the need to carry out Digital Signal Processing using a laptop computer (202). The computer needs to be equipped with a high performance processor in order to carry out all of the mathematical calculations required to execute Digital Signal Processing algorithms. In addition, the laptop computer (202) needs to contain large external disk drives in order to store signature information for known chemical and biological samples. The entire apparatus is large, heavy and very costly.

SUMMARY OF THE INVENTION The invention consists of an unknown agent detection methods and an apparatus. The sensing apparatus consists of a sensor and PDA-phone. The method used in this invention is referred to as Laser Induced Spectroscopy. However, in this invention, tunable lasers are used in order to improve results. The sensor contains an array of tunable lasers. A digital controller contained in the sensor controls each laser. The digital controller ensures that the laser emits light in a narrow band of light frequencies.

Typical region for analyzing chemical materials and biological agents is in the 300 nanometers to 900 nanometers of light wavelength. Each laser is tuned to a narrow wavelength of light ; the amount of laser power is also controlled to a given level.

Wavelength and power are set in an appropriate manner so as to obtain a strong emitted spectrum from the unknown agent. Wavelength of the light source is continuously changed from one region of the spectrum to another with an appropriate amount of power in order to detect a strong and reliable spectrum. Each time we change the wavelength and power of the appropriate laser, the detected spectrum is digitized. After the information is digitized, it is sent to a portable Personal Digital Assistant and telephone unit (PDA-phone) for storage. Once an entire sweep of wavelengths and power has been carried out with a corresponding emitted spectrum digitized and stored, the PDA-phone will transmit through wireless means the data to a remote server. The remote server can contain Digital Signal Processing programs used to filter the information. The server can also contain an analysis tool and databases to determine what is the chemical or agent. The server can also connect through the Internet or other means to databases in research laboratories. Once the agent is identified, the system can transmit to the PDA-phone information related to the identity of the agent or instructions on how to proceed if the agent poses a danger to the operator. Arrays of the sensors described ion this invention can be placed in the filed. Data from the array can'be collected through wireless means by using a hub.

An advantage of the invention is that the detected spectrum (305) will exhibit a high signal to noise ratio. This will increase the reliability of the detection.

Another advantage of the invention is that the detection process does not destroy the sample.

Yet another advantage of the invention is that the sensor is portable and exhibits increased accuracy due to the use of databases in remote server (403)

BRIEF DESCRIPTION OF THE DRAWINGS Details of the invention, and of the preferred embodiment thereof will be further understood upon reference to the drawings: Figure 1 illustrates the present methods for sensing agents.

Figure 2 is an apparatus used for identification of agents with the current methods Figure 3 illustrates the methods used in this invention Figure 4 is an apparatus for agent identification used by an embodiment of the present invention.

Figure 5 is a diagram of the portable optical bio-chemical sensor in this invention DETAILED DESCRIPTION OF AN EMBODIMENT Figure 3 illustrates the methods for sensing agents in this invention. A portable sensor (301) contains an array of tunable lasers, The portable sensor (301) emits laser light of a narrow spectrum (302). The unknown agent (303) absorbs the laser light (302).

Atoms in the unknown agent (303) absorbed the laser light and in turn put out an emitted spectrum of light (304). The spectrum is detected by an internal detector inside of the sensor (301), which stores the information. The sensing process continues with the sensor (301) sweeping through slices of the spectrum of laser light (302) by tuning internal lasers. Each time a different slice of the spectrum is applied to the unknown agent (303), a corresponding emitted spectrum (304) is detected. Because only the response of the unknown agent (303) is detected one slice of spectrum at a time, the detected spectrum (304) will produce an improved response with a lower amount of noise as shown in the graph (305).

Figure (400) shows the entire apparatus and methods for agent identification. Once the emitted spectrum (305) is sensed by the probe (301), information is transferred through the wireless link to a compatible PDA-phone (401). The PDA-phone (401) transfers the sensor information through wireless transmission (402) to a remote server (403). The remote server (403) contains high performance computers and extensive databases to conduct an analysis of the spectrum for the unknown agent (103). The remote server (403) can be connected by alternative means to extensive databases resident in research centers. The remote server performs unknown agent identification using information form the databases. Once the identity of the agent has been established, the server will transmit to the PDA-phone appropriate instructions regarding actions to be taken by the operator or precautions if the agent poses a danger.

Figure 5 illustrates a possible embodiment of a portable sensor (301). An array of tunable lasers (501-504) is connected to an optical head (505). Each one of the tunable<BR> <BR> <BR> <BR> <BR> lasers (501-504) is used to provide narrow band laser light (302). Depending on the unknown agent (103) more lasers than shown in the figure could be required. The optical head (505) collects the light from all lasers (501-504), focuses the light and puts out a beam (302). The beam in turn is applied to a sample folder (506), which contains the unknown agent (103). The emitted spectrum (304) is collected by a detector (507). The detector may be implemented with an optical spectrum analyzer containing a charged coupled device. For some applications, the charged coupled device may be substituted with a simple photodiode detector. The portable sensor (301) also contains a heater cooler (508), which is used to control the temperature of the lasers (501-504). A laser array controller and tuner (509) is used to set the

temperature of the heater cooler (508) to the required value in order to produce laser light (501-504) to the correct wavelength. Battery and powers supply (510) are also part of the portable sensor (301). A wireless transceiver (511) is used to send the sensor information to the PDA-phone (401).