Fig. 5

Photo image (a), typical Raman spectra (b), and Raman intensity images (c–f) collected from the paint branches distributed on a glass surface. In a, the area of 15 μm × 15 μm is scanned. Raman spectra were collected under an objective lens of 100×, integration time of 1 s for each pixel of 0.33 μm × 0.33 μm (to create a spectrum matrix of 45 × 45). b Shows the Raman spectrum of ABS (with intensity off-setting for presentation), to compare with 3 typical spectra collected from the positions marked in a, and the scanning average spectrum. The intensity images (c–e) are mapped at a new peak one at ~ 1100 cm⁻¹ (c), acrylic at ~ 2910 cm⁻¹ (d) and colourant at ~ 440 cm⁻¹ (e), as marked under each image (and the peak width), after 20% colour off-setting. f Merges (c–e), using 3D presentation and white background