Fig 1.
(a) Soda-lime glass with a hole, (b) flat soda-lime glass, (c) flat synthetic quartz glass, (d) flat mirror-finished stainless steel (SUS304) plate, and (e) designed mirror-finished stainless steel (SUS304) plate with holes for obtaining Raman scattering spectra of liquid samples.
Fig 2.
Raman scattering spectra of ethanol (99.5%) obtained using a 785-nm laser and substrates consisting of soda-lime glass with a hole, flat soda-lime glass, and flat synthetic quartz glass.
Each sample was irradiated by a 785-nm laser at an output power of 50 mW for 1 s, and the average of three recorded spectra was taken as the measured spectrum. The focal positions of the laser for the soda-lime glass with a hole, flat soda-lime glass, and flat synthetic quartz glass slide were respectively set to 300, 700, and 700 μm from the lower surface of the cover glass.
Fig 3.
Raman scattering intensity at 886 cm-1 of ethanol (99.5%) obtained employing a 785-nm laser on soda-lime glass with a hole, flat soda-lime glass, and flat synthetic quartz glass substrates.
The focal position of the laser in the soda-lime glass with a hole, flat soda-lime glass, and flat synthetic quartz glass cases was shifted in increments of 100 μm from the lower surface of the cover glass to depths of 1, 2, and 3 mm, respectively. For each focal position, irradiation was performed with the 785-nm laser at an output power of 50 mW for 1 s, and the average of three recorded spectra was taken as the measured spectrum. The Poisson distribution with λ value of the smoothed line of each measured value was set to 0.01.
Fig 4.
Raman scattering spectra of ethanol (99.5%) obtained using a 785-nm laser and flat synthetic quartz glass with or without a flat mirror-finished stainless steel plate as the substrate.
For each focal position, irradiation was performed with the 785-nm laser at an output power of 50 mW for 1 s, and the average of three recorded spectra was taken as the measured spectrum. The focal position of the laser was set to a depth of 700 μm from the lower surface of the cover glass. Fifteen spectra recorded using only flat synthetic quartz glass and 15 spectra recorded with a flat mirror-finished stainless steel plate under the flat synthetic quartz glass are compared.
Fig 5.
Relationships among well diameter, laser focal point, and Raman scattering intensity at 886 cm-1 for ethanol (99.5%) obtained using a 785-nm laser and a stainless steel plate with wells.
A total of 12 different well sizes were employed, with diameters of 2-, 2.5-, and 3-mm and depths of 1, 2, 3, and 4 mm. The laser focal position was shifted in increments of 100 μm from the surface of the plate to the bottom of the well. For each focal position, irradiation was performed with the 785-nm laser at an output power of 50 mW for 1 s, and the average of three recorded spectra was taken as the measured spectrum. The λ value of the smoothed line of each measured value was set to 0.01.
Fig 6.
Raman scattering spectra of ethanol (99.5%) obtained using a 785-nm laser and a stainless steel plate with wells.
For each focal position, irradiation was performed with the 785-nm laser at an output power of 50 mW for 1 s, and the average of three recorded spectra was taken as the measured spectrum. The well diameter was 3 mm in each case, while the well depth was set to 1, 2, 3, and 4 mm and the laser focus was set to 500, 800, 1100, and 1400 μm, respectively, from the surface of the plate.
Fig 7.
Raman scattering spectra of ethanol (99.5%) obtained employing 785- and 1064-nm lasers and a stainless steel plate with a well.
Using a 3-mm-diameter, 4-mm-deep well, the laser focal position was set at 1500 μm from the surface of the plate. The 785-nm laser irradiation was performed for 1, 2, and 3 s at an output power of 50 mW. The 1064-nm laser irradiation was performed for 1, 2, and 3 s at output powers of 50, 100, and 200 mW. The average of three recorded spectra was taken as the measured spectrum.
Fig 8.
Relationship between laser focal point and Raman scattering spectra of human serum obtained utilizing a 785-nm laser and a stainless steel plate with a well.
Using a 3-mm-diameter, 4-mm-deep well, 785-nm laser irradiation was performed for 5 s at an output power of 50 mW. The measurements were performed while shifting the focal position of the laser from 0 to 4 mm from the surface in increments of 100 μm.
Fig 9.
Relationship between integration time and Raman scattering spectra of human serum obtained employing a 785-nm laser and a stainless steel plate with a well.
Using a 3-mm-diameter, 4-mm-deep well, 785-nm laser irradiation was performed at an output power of 50 mW. The focal position of the laser was set to a depth of 500 μm from the surface. The measurements were conducted while varying the integration time from 1 to 60 s.
Fig 10.
Relationship between laser focal point and Raman scattering spectra of human serum obtained employing a 1064-nm laser and a stainless steel plate with a well.
Using a 3-mm-diameter, 4-mm-deep well, 1064-nm laser irradiation was performed for 5 s at an output power of 200 mW. The measurements were performed while shifting the focal position of the laser from 0 to 4 mm below the surface in increments of 100 μm.
Fig 11.
Relationship between integration time and Raman scattering spectra of human serum sample obtained employing a 1064-nm laser and a stainless steel plate with a well.
Using a 3-mm-diameter, 4-mm- deep well, 1064-nm laser irradiation was performed at an output power of 200 mW. The focal position of the laser was set to a depth of 500 μm below the surface. The measurements were conducted while varying the integration time from 1 to 30 s.