# Regulated Power Supply with High Power Factor for Hyperspectral Imaging Applications
###### Abstract  
Illumination is a crucial factor in hyperspectral imaging systems. In this respect, this work is focused on analyzing the influence of the light power source in acquiring hyperspectral images. To this end, a custom regulated power supply was designed and developed. This power supply was then integrated into a hyperspectral acquisition system, and several light stability measurements were conducted. Finally, several parameters related to the stability of the light produced by those systems were extracted using image analysis techniques, and a statistical comparison among the different power supplies was performed. Two commercial power supplies were also analyzed under the same experimental conditions and compared with the proposed power supply. The hyperspectral measurements were conducted using light transmission and reflectance. The results indicate that the proposed power supply performs better than or at least as well as commercial power supplies in terms of light stability. Additionally, this study shows the impact of power supply design on the stability and quality of hyperspectral illumination, especially concerning the signal-to-noise ratio (SNR) across different spectral bands. It is shown that optimizing the design of the power supply could improve light stability in hyperspectral imaging applications. hyperspectral imaging; regulated power supply; power factor; illumination system +
Footnote †: journal: Applied sciences  
0000-0001-9900-0000-0001-9900-0000-0001-9900-00001-9900-00001-99000-00001-99000-00001-99000-00001-990001-990001-990001-990001-990001-990001-990001-990001-990001-990001-990001-90001-99001-990001-90001-990001-9 quality inspection [3; 4], art restoration [5; 6], industrial sorting of materials [7], forensic analysis [8], and medical applications [9; 10], among others. The workflow for these applications typically consists of using HS instruments to collect datasets, and then using various image processing and machine learning techniques to extract useful information from the HS images. A crucial part of this process is the acquisition of the HS data. Data are highly dependent on instrumentation. There are four key elements in every HS acquisition system: (i) the lens used to focus the object to be measured; (ii) the optical element able to separate the incoming light into specific wavelengths; (iii) the electronic sensor to digitalize the information; and (iv) the light source used to illuminate the objects under examination. Each element of the acquisition system affects its overall spectral response [11]. Significantly, the spectral shape of the light source limits the spectral range of the acquisition system, and cameras are required to be stimulated by light sources with a broadband spectral range. Typically, halogen or Xenon-based light sources are employed due to their broadband emission in the visible and infrared regions of the electromagnetic spectrum. Recent studies have compared different light sources, showing that, for specific applications, halogen-based illumination systems work better than LED-based illumination systems in HS image acquisition [12]. Since illumination is a critical factor in HSI systems, some authors have focused their research on measuring the influence of illumination in HSI measurements. These research works cover the influence of the spatial distribution of light [13; 14], the light intensity [15], or the spectral shape of the light source [12; 16]. In a work that discusses the current calibration problems and their possible solutions in HSI, [PERSON] et al. defined a list of properties that an ideal illumination system should have for HSI applications [17]. These properties cover, among others, spatial homogeneity over larger areas, broadband emission, and high intensity. However, as far as we are concerned, the influence of the light power source on the acquisition of HS images has not yet been addressed in the scientific literature. Commercial illumination systems present two main drawbacks.