## 1 Introduction  
Due to its strong scattering and absorption characteristics in the atmosphere and its low background noise, ultraviolet light has been widely used in short-range atmospheric non-line-of-sight optical communication [1; 2; 3], near-field wind-field detection [4], aircraft landing aid [5], atmospheric parameter measurement [6], and networking aspects [7] in recent years, in both to theoretical and experimental studies.  
The atmosphere is mainly composed of air molecules and aerosols. There are two main types of ultraviolet light scattering that occur in the atmosphere: Mie scattering (aerosols) and Rayleigh scattering (molecules) [8]. UV light contains three spectral bands, UVA (320-400 nm), UVB (280-320 nm), and UVC (200-280 nm). Different UV spectral bands lead to different SSA (single scattering albedo) and AAOD (absorption optical depth) values [9]. These two parameters are the main items measured in many experimental contexts [10; 11; 12; 13; 14].  
Studies on UV none-line-of- sight (NLOS) communication mainly deal with UV devices, channel models, physical layer issues, and networking [3; 15]. All these areas, without exception, relate to the transmission of ultraviolet light in atmosphere, which is mainly characterized by the shape of the received signal and the received energy density. For UV light sources, mercury lamps and xenon flash lamps were used for communication in early experimental studies. UV LEDs and lasers have become a research hot-spot in recent experimental research. However, there is currently little theoretical research regarding the influence of the light source on the received signal in UV communication and detection.  
By reviewing previous relevant studies, various research methods for UV atmospheric scattering channel modeling were identified. The ellipsoidal coordinate was used to solve the single-scattering issue in References [16; 17]. Subsequently, the coplanar [18; 19] and non-coplanar transmission models [20; 21] were proposed. In addition, in reference [22; 23], the characteristics of UV atmospheric scattering in turbulent have been comprehensively studied. The above-mentioned theoretical models all assume that the light source is a spot with uniform intensity distribution. In fact, the light intensities from different light sources change in a variety of ways with viewing angle. Therefore, we wanted to further explore the effect of the light source on the received signal. For experimental studies, an LED array was used as a light source in reference [24]. And the black background noise and path loss were measured through experiments on the test bench. The pulse-broadening effect in atmospheric transmission was experimentally characterized using a narrow-pulse ultraviolet laser in Reference [25]. UV LEDs and avalanche photodiodes were used, respectively, for NLOS UV communication in References [26; 27]. It was shown in Reference [28] that a square matrix receiver was proposed to study the spatial diversity in a new way. These experiments applied empirical methods and the numerical simulation of light sources needs to be further explored. The Monte Carlo point probability method is an efficient and time-saving technique for this purpose.  
In this article, in order to explore the influence of different light sources on the received signal, models of different light sources were first established by using the curves of the lights' intensity distributions. In other words, the initial distributions of large numbers of photons were used to generate simulations for different light sources. The trajectories of large numbers of photons were then recorded by MC point probability method. By changing different geometric parameters, the received irradiance levels of different light sources were compared in single and multiple scattering. The coplanar and non-coplanar issues were also considered.