Research Papers

Application of modified difference absorption method to stand-off detection of alcohol in simulated car cabins

[+] Author Affiliations
Jan Kubicki

Military University of Technology, Institute of Optoelectronics, Kaliskiego 2 Street, 00-908 Warsaw, Poland

Jaroslaw Młyńczak

Military University of Technology, Institute of Optoelectronics, Kaliskiego 2 Street, 00-908 Warsaw, Poland

Krzysztof Kopczyński

Military University of Technology, Institute of Optoelectronics, Kaliskiego 2 Street, 00-908 Warsaw, Poland

J. Appl. Remote Sens. 7(1), 073529 (Jul 31, 2013). doi:10.1117/1.JRS.7.073529
History: Received December 17, 2012; Revised June 5, 2013; Accepted June 14, 2013
Text Size: A A A

Open Access Open Access

Abstract.  Some aspects of stand-off detection of alcohol in simulated car cabins are described. The proposed method is the well-known “difference absorption” method applied to the differential absorption lidar system, modified by taking advantage of a third laser beam. The modification was motivated by the familiar physical phenomena such as dispersion and different absorption coefficients in window panes for applied laser wavelengths. The mathematical expressions for the method were derived and confirmed by experiments. The presented investigations indicate that the method can be successfully applied to stand-off detection of ethyl alcohol in moving cars.

Figures in this Article

There are many papers dealing with stand-off detection of different chemical and biological compounds with the use of a monochromatic laser beam at a wavelength fitting into the absorption spectra of these materials.16 At the same time, many new developments in lasers that can be used in this application have been achieved in recent years.712 Thus many devices based on this technology were presented in laboratories as well as applied to civil industry, environmental protection, and military. The differential absorption lidars (DIAL) are the most often used systems to monitor the atmosphere and detect contaminants in the form of gas, aerosol, fume, or dust. They make use of the well-known physical phenomenon of “difference absorption” using two laser beams at different wavelengths. Among many advantages of these systems are the ability to analyze the sample without the necessity to collect it, real-time investigation as well as integration of electro-optical systems and full automation of the measurement. Moreover the time needed to take measurements is equivalent to the speed of light; thus such lidars can be successfully used to face alcohol abuse among drivers.

Ethyl alcohol is a chemical compound that is characterized by high volatility, reflection of which is its high concentration on exhalation of people who have consumed it. Thus the car cabin where the drunken people are located is expected to be filled with air having some concentration of alcohol. In such situations, the simple DIAL system seems to work properly enough to detect the concentration of alcohol in the cabin, but it is not so. In order to assure the reliable results of measurements, the physical phenomena appearing in the side window panes of the car have to be taken into account. In this connection, a new method of detection was proposed and described in this article as well as in three patents and a study.1315

To effectively detect chemicals in cars using the difference absorption method, it is essential to know not only its transmission spectra but also the transmission spectra of accompanying substances as well as transmission spectra of the side window panes of cars. In this case the accompanying substances that have to be taken into consideration are carbon dioxide (CO2) and water vapor (H2O). In Fig. 1, the measured transmission spectra of vapor of ethanol (rectified spirit), CO2, vapor of H2O, and window pane are presented. To measure the spectra, the first three chemical compounds were placed inside a 12-cm-long glass pipe terminated by quartz windows. The windowpane used for experiments was made of flot glass by Pilkington company and is the most often used window pane in cars.

Grahic Jump LocationF1 :

Transmission spectra of chemicals that can appear on the way of the laser beams.

Ethyl alcohol is characterized by a quite wide absorption band around the 3.39 μm wavelength, which is mainly caused by stretching vibrations of OH, CH, and CO bonds being included in C2H5OH molecule.16 This situation is very useful for the choice of the wavelength absorbed by the alcohol, but at the same time it implies the necessity of choosing the reference wavelength, which lies relatively far from the previous one. The absorption band around 3 μm wavelength is caused by water that occurs in rectified spirit.

Keeping in mind the measured transmission spectra and availability of lasers, it seems that the He–Ne laser generating at 3.39 μm wavelength, strongly absorbed by the alcohol, is the best option. For reference beam, a laser diode generation at 1.5 μm wavelength was chosen. Using only two wavelengths is not enough to detect alcohol because of the window pane, which has different transmission for these wavelengths as well as different thicknesses in different cars. If the thickness was the same for all cars or the transmission was the same for both wavelengths, there would not be any problem with the detection. However, the differences are quite big and using the third wavelength, which will enable measurement of the thickness of the windowpane, becomes necessary. The third wavelength should have a transmission different from that of 1.5 μm wavelength and lie outside the absorption bands of alcohol, CO2, and H2O. Laser diode generation at 1.3 μm wavelength seems to be a reasonable solution. The chosen wavelengths are indicated in Fig. 1 by straight vertical lines.

Very important phenomena that should be taken into account are dusting and misting over window panes. To face these problems, transmission spectra of clean window panes and those covered with water vapor, road dust, and graphite dust were measured and presented in Fig. 2.

Grahic Jump LocationF2 :

Transmission spectra of clean windowpane (1), windowpane covered with water vapor (2), windowpane covered with road dust (3), windowpane covered with graphite dust (4).

To calculate the transmission of the layers of dust and water vapor, the transmissions of the covered window panes were divided by the transmission of the clean window pane at selected wavelengths. The results of the calculations are presented in Table 1, where T1 is the transmission of the clean window pane, T2 is the transmission of the window pane covered with water vapor, T3 is the transmission of the window pane covered with road dust, T4 is the transmission of the window pane covered with graphite dust, Tw is the transmission of water vapor, Trd is the transmission of road dust, Tgd is the transmission of graphite dust, and λ is the wavelength.

Table Grahic Jump Location
Table 1Transmissions of the layers of dust and water vapor.

Looking at the results of calculations it seems that the appearance of dust does not have any influence on the results of measurement of the concentration of alcohol, because its transmission at the investigated wavelengths is almost the same. Water vapor has lower transmission at 3.39 μm and then at 1.3 and 1.5 μm wavelengths, which is not desired; however, the difference is so small that it should not interfere with the detection of alcohol.

The window pane used for the experiments was the same as in the previous investigations. The transmission spectra of the window pane before and after thermal processing (tempering and bending) with thickness of 3.15 mm were measured and are presented in Fig. 3.

Grahic Jump LocationF3 :

Transmission spectra of windowpane before and after thermal processing.

In Table 2 the transmissions T(λ) of the window panes at the investigated wavelengths λ are presented. As can be seen from the table, the tempering does not significantly change the transmission of the window pane at any of the investigated wavelengths. Thus for the next experiments, a window pane that was not tempered was used since it is easier to machine (cutting, grinding, polishing).

Table Grahic Jump Location
Table 2Transmissions of windowpanes at the investigated wavelengths.

Because the optical parameters of the flot glass used for the production of the window panes are not available from the producer in the investigated spectral range, they had to be measured. The parameters that are indispensable for accurate detection of alcohol are absorption coefficient and refractive index.

In order to calculate the absorption coefficient of the window pane, the transmission spectra of two samples of flot glass with thickness of d1=1.5mm and d2=3mm were measured. The transmission spectra are presented in Fig. 4, while in Table 3 the transmissions T(λ) at the investigated wavelengths λ are shown.

Grahic Jump LocationF4 :

Transmission spectra of two samples of flot glass with thickness of 3 and 1.5 mm.

Table Grahic Jump Location
Table 3Transmissions T(λ) at the investigated wavelengths λ.

Assuming that there is no scattering on the surface of the sample and inside it, the intensity of the radiation going through it can be written as Display Formula

I=I0(1r)eκd(1r)+I1reκdreκd(1r)+,(1)
where I0 is the intensity of the incident radiation, Display Formula
I1=I0(1r)eκd,(2)
r is the reflection coefficient, κ is the absorption coefficient, and d is the thickness of the sample.

In the investigated situation, Display Formula

r2eκdr,(3)
and the transmission of the sample can be described as Display Formula
T=II0=(1r)2eκ·d.(4)

Introducing the following notation for radiation at a specified wavelength λ, Display Formula

F(λ)Fλ,
Eq. (4) can be written as Display Formula
T(d,λ)=T0λeκλd,(5)
where Display Formula
T0λ[1r(λ)]2.(6)

For the samples with thickness of d1=1.5mm and d2=3mm, Display Formula

Td2λ=T0λeκλ3,(7)
Display Formula
Td1λ=T0λeκλ1.5.(8)

After dividing Eq. (7) by Eq. (8), Display Formula

Td2λTd1λ=eκλ1.5.
Thus Display Formula
κλ=11.5ln(Td1λTd2λ).(9)

Taking into account the transmissions from Table 3, the absorption coefficients for the investigated wavelengths are Display Formula

κ1.3=0.0384mm1,κ1.5=0.0266mm1,κ3.39=0.479mm1.(10)

Squaring both sides of Eq. (8), Display Formula

(Td1λ)2=(T0λ)2eκλ3.(11)

Dividing Eq. (11) by Eq. (7), Display Formula

(Td1λ)2Td2λ=T0λ.(12)

Thus for three investigated wavelengths, Display Formula

T01.3=0.92394,T01.5=0.91929,T03.39=0.94991.(13)

The refractive index of the window pane was determined by the use of the experimental setup shown in Fig. 5. During the experiment the laser beams were passing through the wedge made of flot glass with the vertex angle of Φ=9°40 and the angular deviation δ was measured by a detector. The experiment was repeated for three investigated wavelengths.

Grahic Jump LocationF5 :

Experimental setup for determining the refractive index of the windowpane.

The measured angular deviations were equal to Display Formula

δ1.3=5°2,δ1.5=4°58,δ3.39=4°37.

Using the expression Display Formula

nλ=sin(φ+δ)sinφ,(14)
the refractive indexes can be calculated to be equal to Display Formula
n1.3=1.51,n1.5=1.50,n3.39=1.47.(15)

The calculated absorption coefficients, refractive indexes, and transmissions T0(λ) are presented in Table 4.

Table Grahic Jump Location
Table 4Calculated absorption coefficients, refractive indexes, and transmissions T0(λ).

The commercially available lasers are characterized by relatively high power instability. Moreover, the strong absorption of the 3.39 μm wavelength by a window pane implies the necessity to use detectors with very high sensitivity, which, in the case of lack of window pane, causes saturation of the detectors. These obstacles can be solved by the application of comparative method using two detectors for measuring the optical power before and behind the glass pipe simulating a car and additionally using the reference glass pipe with known optical parameters. The method is schematically presented in Fig. 6.

Grahic Jump LocationF6 :

Diagram of comparative method.

In the absence of any glass pipe, the laser beam is divided by the beam splitter into beam I01 incident on detector 1 and beam I02 incident on detector 2. Because of the instability of the laser, its power can change in time by the index k. Thus, after inserting the investigated glass pipe in the laser beam, the intensity can be described as Display Formula

IIk.

As a result of this, the transmission of the glass pipe can be expressed as Display Formula

Tk=I2kI02.(16)

Assuming that there is no change of polarization and power distribution in the laser beam, the k index can be described as Display Formula

k=I1I01.

Inserting this expression into Eq. (16), Display Formula

Tk=I2I01I02I1=I01I02I2I1.(17)

Introducing notations Display Formula

I2I1i,I02I01i0,(18)
Eq. (17) can be written as Display Formula
Tk=ii0.(19)

Inserting the reference glass pipe with known transmission Twk in the laser beam and measuring the intensities I2w and I1w and at the same time introducing the expression iwI2w/I1w, the equation for the transmission Twk can be written as Display Formula

Twk=iwi0.
Thus, Display Formula
i0=iwTwk.

After inserting this into Eq. (19), the transmission of the investigated glass pipe is Display Formula

Tk=Twkiiw.(20)

Assuming that the reference glass pipe is terminated by glass windows with thickness of d and is empty, its transmission can be described as Display Formula

Twk=(T0)2e2κd.(21)

On the other hand, the transmission of the investigated glass pipe filled with alcohol vapor with transmission of Ta terminated by the same windows as in the case of the reference glass pipe, covered with some material with transmission of Tp, can be expressed as Display Formula

Tk=(T0)2TaTpe2κl,(22)
where l is the distance inside the window that the laser beam has to pass through.

After inserting Eqs. (21) and (22) into Eq. (20), Display Formula

TaTp=iiwe2κ(ld).(23)

For a wavelength λ, Eq. (23) can be written as Display Formula

Ta(λ)Tp=iλiwλe2κλ[l(λ)d].(24)

If the normal to the window pane with thickness of d is not parallel to the laser beam, the distance that the laser light has to pass through inside the window can be described as Display Formula

l(λ)=d1sin2αnλ2,(25)
where α is the angle of incidence of the laser beam onto the window pane.

Taking into account the calculated refractive indexes from Table 4, the relative difference of l for extreme wavelengths (1.3 and 3.39 μm) at α=20deg can be expressed as Display Formula

δl(1.3)l(3.39)l(1.3)<d1sin20°1.512d1sin220°1.472d1sin220°1.512=0.0015.(26)

In this case, it can be assumed that for α<20degDisplay Formula

l(1.3)l(1.5)l(3.39)=l.(27)

Thus Eq. (24) can take the form of Display Formula

Ta(λ).Tp=iλiwλe2κλΔ,(28)
where Δ=ld.

Assuming that the difference between l and d is very small (at α=20deg, 2κ3.39Δ=0.08), it can be written that Display Formula

e2κλΔ1+2κλΔ.(29)

In this case, Eq. (28) for the investigated wavelengths takes the form of Display Formula

TpTa=i3.39iw3.39(1+2κ3.39Δ),(30)
Display Formula
Tp=i1.5iw1.5(1+2κ1.5Δ),(31)
Display Formula
Tp=i1.3iw1.3(1+2κ1.3Δ).(32)

After solving the above equations, Display Formula

Δ=12κ1.31iw1.3iw1.5i1.5i1.3κ1.5κ1.3iw1.3i1.5iw1.5i1.31,(33)
Display Formula
Tp=(κ1.5κ1.3)κ1.3i1.5iw1.5κ1.5κ1.3iw1.3i1.5iw1.5i1.31,(34)
Display Formula
Ta=κ1.5κ3.39κ1.5κ1.3i3.39iw3.39iw1.3i1.3κ1.3κ3.39κ1.5κ1.3i3.39iw3.39iw1.5i1.5.(35)

Inserting the notation Display Formula

aλiλiwλ,(36)
Eqs (33), (34), and (35) can be expressed as Display Formula
Δ=12a1.3a1.5κ1.5a1.5κ1.3a1.3,(37)
Display Formula
Tp=a1.3a1.5κ1.5κ1.3κ1.5a1.5κ1.3a1.3,(38)
Display Formula
Ta=κ1.5κ3.39κ1.5κ1.3a3.39a1.3κ1.3κ3.39κ1.5κ1.3a3.39a1.5.(39)

Inserting the calculated absorption coefficients into the above equations, Display Formula

Δ=12a1.3a1.50.0266a1.50.0384a1.3,(40)
Display Formula
Tp=a1.3a1.50.01180.0384a1.30.0266a1.5,(41)
Display Formula
Ta=38.297a3.39a1.337.297a3.39a1.5.(42)

The investigations of the detection of alcohol in the glass pipe simulating a car cabin were carried out in the setup presented in Fig. 7. Four lasers generating at 3.39, 1.5, 1.3, and 0.6 μm wavelengths were used. Their beams were combined into one single beam by glass plates with appropriate thin-layer coatings. The laser generating wavelength at 0.6 μm was used as a pointer to make the adjustment of the system easier. All lasers worked in continuous regime, so the chopper for modulation was used. Small displacement of different laser beams at the surface of the chopper enabled separation of the beams in time domain so as to have been detectable by only two detectors. Two glass pipes with lengths of 140 cm and diameter of 5 cm terminated by the flot glass with thickness of 3.15 mm were used. One of them was the reference glass pipe with clean windows that were perpendicular to the laser beam. The second one was the investigated glass pipe filled with different concentrations of alcohol vapor with windows at angles of 15 deg to the laser beam, covered with graphite dust.

Grahic Jump LocationF7 :

Experimental setup for detection of alcohol in glass pipe.

Two PbSe detectors were used and the signals were registered by an oscilloscope. In Fig. 8 the picture of the screen of the oscilloscope is presented. The experimental results and calculations are shown in Table 5.

Grahic Jump LocationF8 :

Picture of the screen of the oscilloscope.

Table Grahic Jump Location
Table 5Experimental results and calculations.

Inserting the calculated aλ in Eq. (42), the transmission of the alcohol can be expressed as Display Formula

Ta=1.4784a3.39.(43)

To prepare the required concentration of the alcohol vapor inside the investigated glass pipe, the appropriate volume of saturated vapor of alcohol was injected into it with the use of a syringe. On the basis of physical tables, the pressure of saturated alcohol vapor was assumed to be 60 hPa at the temperature of 20°C. Thus the concentration of the alcohol vapor in mole fraction can be described as Display Formula

C=60hPa1013.2hPa=0.059.(44)

Changing the units into particle per million (ppm), the concentration can be expressed as Display Formula

C=0.059×106=59,000ppm

Multiplying C by the ratio of the volume of the injected alcohol vapor and the volume of the glass pipe (2749cm3), the concentration of the alcohol vapor in the investigated glass pipe was determined. The results of the investigations for different concentrations of alcohol vapor are shown in Table 6. In Fig. 9 the transmission of alcohol vapor as a function of concentration is presented.

Table Grahic Jump Location
Table 6Results of investigations of detection of alcohol vapor at different concentrations.
Grahic Jump LocationF9 :

Transmission of alcohol vapor as a function of concentration.

In the presented experiment the accuracy of measurement of the signals from the detectors appears to be very crucial in order to assure reliable results. Applying the uncertainty theory and assuming that a man having a concentration of alcohol of 0.2‰ in his blood breathes out 0.1mg/dcm3 of it, which corresponds with the alcohol concentration of 50 ppm,17,18 the accuracy of the detection of relative value of the laser radiation should be at least Δi<3×104.

The results of the experiments prove that the proposed modified difference absorption method of detection of alcohol is reliable. Even if there is an angular tilting of the car windows with respect to the laser beam and car windows are dirty, the proposed solution can work properly. Thus the development of a trustworthy device seems to be feasible.

The work was sponsored by the Polish National Centre for Research and Development, project INNOTECH-K1/IN1/24/153656/NCBR/12.

Silverstein  R. M., Bassler  G. C., Morrill  T. C., Spectrometric Identification of Organic Compounds. ,  John Wiley & Sons ,  New York  (1991).
Demtröder  W., Laser Spectroscopy. ,  Springer-Verlag ,  Berlin  (2002).
Farsund  Ø., Rustad  G., Skogan  G., “Standoff detection of biological agents using laser induced fluorescence—a comparison of 294 nm and 355 nm excitation wavelengths,” Biomed. Opt. Express. 3, (11 ), 2964 –2975 (2012), CrossRef. 2156-7085 
Wlodarski  M. et al., “Fluorescence excitation-emission matrices of selected biological materials,” Proc. SPIE. 6398, , 639806  (2006), CrossRef. 0277-786X 
Feugnet  G. et al., “Improved laser-induced fluorescence method for bio-attack early warning detection system,” Proc. SPIE. 7116, , 71160C  (2008), CrossRef. 0277-786X 
Mierczyk  Z. et al., “Fluorescence/depolarization LIDAR for mid-range stand-off detection of biological agents,” Proc. SPIE. 8031–8040, , 80371J  (2011), CrossRef. 0277-786X 
Sotor  J., Sobon  G., Abramski  K. M., “Er-doped fibre laser mode-locked by mechanically exfoliated graphene saturable absorber,” Opto-Electron. Rev.. 20, (4 ), 362 –366 (2012), CrossRef. 1230-3402 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Investigations of optical and generation properties of Yb-Er laser glasses (SELG) designed for 1.5 μm microlasers,” Proc. SPIE. 6599, , 65990D  (2007), CrossRef. 0277-786X 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Optimization of passively repetitively Q-switched three-level lasers,” J. Quantum Electron.. 44, (12 ), 1152 –1157 (2008), CrossRef. 0018-9197 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Generation investigation of ‘eye-safe’ microchip lasers pumped by 974 nm and 939 nm wavelength,” Optica Applicata. 38, (4 ), 657 –668 (2008). 0078-5466 
Mlynczak  J. et al., “Comparison of cw laser generation in Er3+, Yb3+: glass microchip lasers with different types of glasses,” Opto-Electron. Rev.. 19, (4 ), 87 –91 (2011), CrossRef. 1230-3402 
Mlynczak  J. et al., “Pulse generation at 1.5 μm wavelength in new EAT14 glasses doped with Er3+ and Yb3+ ions,” Opto-Electron. Rev.. 20, (1 ), 14 –17 (2012), CrossRef. 1230-3402 
“Urządzenie do wykrywania par alkoholu w poruszających się pojazdach,” Patent No. P.389627.
“Urządzenie do zdalnego wykrywania par i gazów metodą DIAL w kabinach i komorach z oknami,” Patent No. P-398513.
“Urządzenie do zdalnego określania kąta nachylenia szyby bocznej poruszającego się samochodu,” Patent No. P-399366.
Volland  W., Organic Compound Identification Using Infrared Spectroscopy. ,  Bellevue Community College ,  Washington  (1999).
Bretsznajder  S., Własności gazów i cieczy. ,  Wydawnictwo Naukowo-Techniczne ,  Warsaw  (1962).
Polish Law, Ustawa o wychowaniu w trzeźwości i przeciwdziałaniu alkoholizmowi, Art. 46, Dz. U. 2002, No 147 item 1231.

Grahic Jump LocationImage not available.

Jan Kubicki is a graduate from the Military University of Technology, Warsaw, Poland. In 1980, he received a PhD in the field of molecular lasers. Currently he works at the Institute of Optoelectronics of Military University of Technology. He is an author and co-author of many scientific papers in the field of laser physics, laser spectroscopy and high power laser systems as well as co-author of patents concerning different applications of high power laser pulses and stand-off detection of alcohol.

Grahic Jump LocationImage not available.

Jaroslaw Młyńczak received his MSc in 2002 and PhD in 2008 from the Military University of Technology, Warsaw, Poland, where he currently works as a scientist. His research centers on investigation of new active media and new nonlinear absorbers for UV, VIS, IR and “eye-safe” microchip lasers as well as development of microchip lasers for stand-off detection systems. He also participates in research concerning detection of biological agents in the environment as well as biometric identification of people. He is an author and co-author of many scientific and conference papers.

Grahic Jump LocationImage not available.

Krzysztof Kopczyński received his MSc in solid-state physics and quantum electronics and PhD in the field of laser physics from the Military University of Technology. He is a director of the Institute of Optoelectronics of Military University of Technology. He is a specialist in the field of physics and technology of solid-state lasers, microchip lasers with selective diode pumping, and laser devices for stand-off detection. He is an author and co-author of a few tens of scientific and conference papers.

© The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Citation

Jan Kubicki ; Jaroslaw Młyńczak and Krzysztof Kopczyński
"Application of modified difference absorption method to stand-off detection of alcohol in simulated car cabins", J. Appl. Remote Sens. 7(1), 073529 (Jul 31, 2013). ; http://dx.doi.org/10.1117/1.JRS.7.073529


Figures

Grahic Jump LocationF1 :

Transmission spectra of chemicals that can appear on the way of the laser beams.

Grahic Jump LocationF2 :

Transmission spectra of clean windowpane (1), windowpane covered with water vapor (2), windowpane covered with road dust (3), windowpane covered with graphite dust (4).

Grahic Jump LocationF3 :

Transmission spectra of windowpane before and after thermal processing.

Grahic Jump LocationF9 :

Transmission of alcohol vapor as a function of concentration.

Grahic Jump LocationF8 :

Picture of the screen of the oscilloscope.

Grahic Jump LocationF7 :

Experimental setup for detection of alcohol in glass pipe.

Grahic Jump LocationF6 :

Diagram of comparative method.

Grahic Jump LocationF5 :

Experimental setup for determining the refractive index of the windowpane.

Grahic Jump LocationF4 :

Transmission spectra of two samples of flot glass with thickness of 3 and 1.5 mm.

Tables

Table Grahic Jump Location
Table 1Transmissions of the layers of dust and water vapor.
Table Grahic Jump Location
Table 3Transmissions T(λ) at the investigated wavelengths λ.
Table Grahic Jump Location
Table 6Results of investigations of detection of alcohol vapor at different concentrations.
Table Grahic Jump Location
Table 5Experimental results and calculations.
Table Grahic Jump Location
Table 4Calculated absorption coefficients, refractive indexes, and transmissions T0(λ).
Table Grahic Jump Location
Table 2Transmissions of windowpanes at the investigated wavelengths.

References

Silverstein  R. M., Bassler  G. C., Morrill  T. C., Spectrometric Identification of Organic Compounds. ,  John Wiley & Sons ,  New York  (1991).
Demtröder  W., Laser Spectroscopy. ,  Springer-Verlag ,  Berlin  (2002).
Farsund  Ø., Rustad  G., Skogan  G., “Standoff detection of biological agents using laser induced fluorescence—a comparison of 294 nm and 355 nm excitation wavelengths,” Biomed. Opt. Express. 3, (11 ), 2964 –2975 (2012), CrossRef. 2156-7085 
Wlodarski  M. et al., “Fluorescence excitation-emission matrices of selected biological materials,” Proc. SPIE. 6398, , 639806  (2006), CrossRef. 0277-786X 
Feugnet  G. et al., “Improved laser-induced fluorescence method for bio-attack early warning detection system,” Proc. SPIE. 7116, , 71160C  (2008), CrossRef. 0277-786X 
Mierczyk  Z. et al., “Fluorescence/depolarization LIDAR for mid-range stand-off detection of biological agents,” Proc. SPIE. 8031–8040, , 80371J  (2011), CrossRef. 0277-786X 
Sotor  J., Sobon  G., Abramski  K. M., “Er-doped fibre laser mode-locked by mechanically exfoliated graphene saturable absorber,” Opto-Electron. Rev.. 20, (4 ), 362 –366 (2012), CrossRef. 1230-3402 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Investigations of optical and generation properties of Yb-Er laser glasses (SELG) designed for 1.5 μm microlasers,” Proc. SPIE. 6599, , 65990D  (2007), CrossRef. 0277-786X 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Optimization of passively repetitively Q-switched three-level lasers,” J. Quantum Electron.. 44, (12 ), 1152 –1157 (2008), CrossRef. 0018-9197 
Mlynczak  J., Kopczynski  K., Mierczyk  Z., “Generation investigation of ‘eye-safe’ microchip lasers pumped by 974 nm and 939 nm wavelength,” Optica Applicata. 38, (4 ), 657 –668 (2008). 0078-5466 
Mlynczak  J. et al., “Comparison of cw laser generation in Er3+, Yb3+: glass microchip lasers with different types of glasses,” Opto-Electron. Rev.. 19, (4 ), 87 –91 (2011), CrossRef. 1230-3402 
Mlynczak  J. et al., “Pulse generation at 1.5 μm wavelength in new EAT14 glasses doped with Er3+ and Yb3+ ions,” Opto-Electron. Rev.. 20, (1 ), 14 –17 (2012), CrossRef. 1230-3402 
“Urządzenie do wykrywania par alkoholu w poruszających się pojazdach,” Patent No. P.389627.
“Urządzenie do zdalnego wykrywania par i gazów metodą DIAL w kabinach i komorach z oknami,” Patent No. P-398513.
“Urządzenie do zdalnego określania kąta nachylenia szyby bocznej poruszającego się samochodu,” Patent No. P-399366.
Volland  W., Organic Compound Identification Using Infrared Spectroscopy. ,  Bellevue Community College ,  Washington  (1999).
Bretsznajder  S., Własności gazów i cieczy. ,  Wydawnictwo Naukowo-Techniczne ,  Warsaw  (1962).
Polish Law, Ustawa o wychowaniu w trzeźwości i przeciwdziałaniu alkoholizmowi, Art. 46, Dz. U. 2002, No 147 item 1231.

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Book Chapters

Topic Collections

PubMed Articles
Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Article
Sign in or Create a personal account to Buy this article ($20 for members, $25 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.