1. Report No. 



NASA TN D-8U147 



2. Government Accession No. 



3. Recipient's Catalog No. 



4. Title and Subtitle 



ANALYSIS OF LASER FLUOROSENSOR SYSTEMS FOR 

 REMOTE ALGAE DETECTION AND QUANTIFICATION 



5. Report Date 



June 1977 



6. Performing Organization Code 



7. Author(sl 



Edward V. Browell 



8. Performing Organization Report No 

 L-11007 



9. Performing Organization Name and Address 



NASA Langley Research Center 

 Hampton, VA 23665 



10. Work Unit No. 



176-20-32-07 



11 Contract or Grant No 



12. Sponsoring Agency Name and Address 



National Aeronautics and Space Administration 

 Washington, DC 205^6 



13 Type of Report and Period Covered 



Technical Note 



14 Sponsoring Agency Code 



15. Supplementary Notes 



16. Abstract 



The development and performance of single- and multiple-wavelength laser fluoro- 

 sensor systems for use in the remote detection and quantification of algae are dis- 

 cussed in this paper. The appropriate equation for the fluorescence power received 

 by a laser fluorosensor system is derived in detail, and the result is found to 

 differ by as much as a factor of 10 from those previously reported in the litera- 

 ture. Experimental development of a single-wavelength system and a four -wavelength 

 system, which selectively excites the algae contained in the four primary algal 

 color groups (green, golden-brown, red, and blue-green), is reviewed, and test 

 results are presented. A comprehensive error analysis is reported which evaluates 

 the uncertainty in the remote determination of the chlorophyll a_ concentration 

 contained in algae by single- and multiple-wavelength laser fluorosensor systems. 

 Environmental parameters which can greatly affect the fluorescence cross section 

 of algae include long- and short-term light history and nutrient and age effects. 

 Results of the error analysis indicate that the remote quantification of chloro- 

 phyll a by a laser fluorosensor system requires optimum excitation wavelength( s ) , 

 remote measurement of marine attenuation coefficients, and supplemental instru- 

 mentation to reduce uncertainties in the algal fluorescence cross sections. 

 Without these additional measurements, both the single- and multiple-wavelength 

 laser fluorosensor systems can only provide qualitative information about chloro- 

 phyll & concentration contained in the algae, and the single-wavelength system 

 will yield results which are comparable to a multiple-wavelength system which has 

 optimum excitation wavelengths. 



17. Key Words (Suggested by Author(s)) 



Laser systems 

 Remote sensing 

 Algae detection 

 Chlorophyll a measurement 



19. Security Classif. (of this reportl 



Unclassified 



18. Distribution Statement 



Unclassified 



Unlimited 



Subject Category 36 



20. Security Classif. (of this page) 

 Unclassified 



21 



No. of Pages 



39 



22. Price" 

 $lf . 00 



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