Eye safety for scanning laser projection systems

Abstract

In the growing field of pico-projectors, laser-based scanning systems may be advantageous over DLP- or LCoS-based imagers due to their potential for miniaturization, enhanced optical efficiency and cost reduction. The high energy density of a combined laser beam can, however, be hazardous to the human eye. Laser projection systems must therefore be identified with the laser class, depending on their maximum optical output power. This power limits the brightness of the displayed image, which is of particular interest for mobile applications. Various approaches to classifying laser devices by their wavelength and output power are described within the standards for laser safety. It is found that actual safety regulations cannot be directly applied to scanning systems. A detailed analysis of the optical conditions in terms of a two-dimensional extended light source is appropriate for the consideration of laser scanner devices. In this article, alternative ways of applying laser standards for scanning systems are discussed. The dependencies of maximum luminous flux from scanning system parameters are reviewed. It is shown that the evaluation of retinal light exposure in terms of existing laser regulations leads to an overestimation of the hazardous potential. Advanced investigations are proposed to support the definition of suitable criteria for the classification of laser scanning projectors.

Optimizing flying‐spot display designs based on the upcoming edition of the laser safety standard

“…(8) and also see Refs. and on this), the allowed emission power was halved. The impact of this becomes clear, if one considers the curve for requirement 2a in Fig.…”

“…or . Therefore, T p scanend has to be calculated first using the following equation: θ r is the angle corresponding to the aperture of the human eye and follows from its diameter (7 mm in the presented case) and the distance between the aperture and the scanning vertex, which is 100 mm within this work (this creates the worst‐case scenario, find more details within Ref ). Using this value for T p scanend together with H active , Fig.…”

“…Pulsed lasers have to be evaluated for three different requirements, which therefore apply to flying‐spot displays too (references provide detailed explanations). In the field of laser safety, the worst‐case scenario always needs to be considered.…”

Improving symmetry of nipple–areola complex (NAC) position in reduction mammoplasty using laser level projection

“…For preoperative markings, patients were provided with a pair of conventional laser-safety goggles (P1L15, NIR-filter wavelength 650-665 nm; Laservision GmbH Fürth, Germany). 18 The laser was placed within 1 m of the patient for preoperative markings and within 3 m for intraoperative measurements.…”

Analyses of optical radiation safety standards for laser illuminated products

“…As mentioned in Section , the optical radiation safety of spot scanning, line scanning, and area illumination laser projectors shall be evaluated according to IEC 60825‐1: 2014 or IEC 62471‐5: 2015 if applicable. Most of area illumination laser projectors can meet the applicable requirements so that they can be evaluated according to IEC 62471‐5: 2015 and classified as a class 1 laser product.…”