The concept of OW (with 632.8 nm He–Ne laser), combined with colorimetry based on a reaction of anthrone-sulphuric acid, was proposed as a new tool for determination of lactose in raw milk. Data obtained from various milk samples by OW colorimetry were compared to those acquired from the MilkoScan analyser; the correlation between the two methods is high.
Bakos, P., Doka, O., Ajtony, Z., Bicanic, D., & Szucs, D. (2002). Determination of lactose in raw milks by means of the combined He-Ne laser optothermal window. Instrumentation Science and Technology, 30(2), 167-175. https://doi.org/10.1081/CI-120003896