No abstract

Diffractive optical elements (DOEs) may be used as a single optical component with dedicated functionality (e.g. focusing), or as one of the elements in complex hybrid optical systems to reduce the number of the elements and improve imaging quality. It is desirable to cover DOE’s surface with antireflective coating. In this paper, we show the results of simulations using the Fourier modal method and measure the efficiency of a diffractive lens with antireflective (AR) coating. Results were compared with a previously proposed model of AR covered DOE by Mao et al. [Opt. Express 25, 11673 (2017)10.1364/OE.25.011673]. Contrary to the previously published model, we have not observed a shift of the efficiency curve. Our findings prove that AR coatings improve the efficiency of DOEs and it is not necessary to take them into account when calculating optimal profile height.

Abstract-In this work, we investigate a thin-film polarizer for a high intensity electromagnetic (EM) beam based on Cr nano wire arrays. Commonly used thin-film polarizing components are very sensitive for high power of EM waves and can be easily damaged by focused beams. The solution to this problem could be a thin-film polarizer based on metallic subwavelength structures. This type of optical element has huge resistance compared to typical thin-film polarizers. However, designing such an optical element for the proper wavelength of an EM wave and transmission is not an easy task. In this paper we present numerical as well as experimental results for a specially designed chromium thin-film polarizer for a wavelength of 532nm.

Due to their ecological and financial aspects, water-based lubricants may be competitive in use for production and sustainable technology. The paper presents tribological measurements results in the ball-flat friction node with reciprocal movement. The friction element manufactured of 316L stainless steel and 100Cr6 bearing steel cooperated under mixed friction with the use of water-based lubricants. Firstly, graphene flakes and graphite were applied as lubricant additives, both used as a similar reference material. Secondly, graphene lubricant reduced the friction coefficient and wear of friction elements. Interaction between water and graphene lubricants with 0.1 wt % and 1 wt % of graphene flakes and metal was also investigated. After 30 days of oxidation test in water and graphene lubricants, the Fe sample (Armco iron) surface was covered in graphene flakes with iron oxide structures. A compact coverage of the surface creates a protective layer against intensive oxidation in the distilled water-based graphene lubricant. The tests results have proven that the greater density of graphene flakes in the lubricant, the smaller is the amount of detected oxides. Graphene flakes agglomeration was observed in contact with the iron metal.

Pelvic floor muscle dysfunctions can lead to urinary incontinence, a condition which often affects women both during pregnancy and after childbirth. As a result of this, certain exercises are recommended during and after pregnancy to prevent and treat this incontinence, and the BeBo Concept is one of these methods used to prevent pelvic floor muscle dysfunction. The aim of the present study was to evaluate the effects of a 6-week course of physical therapy according to the BeBo Concept on the improvement of perineal muscle strength and endurance as well as urinary continence in women after their first vaginal delivery. The study was conducted on a group of 56 women who were randomly assigned to the exercise (n = 30) or control (n = 26) group. The exercising group participated in a 6-week physical therapy program according to the BeBo Concept. Pelvic floor muscles were assessed using the perineometer and palpation Perfect Test. UDI6 and ICIQ-SF questionnaires were used to obtain information about the symptoms of urinary incontinence, evaluate the frequency, severity and impact of urine leakage on the quality of life. In all women after natural childbirth, regardless of treatment, it was observed that measured parameters improved, but the improvement was slightly more explicit in those who participated in the Bebo Concept exercise group (e.g. ICIQ-SF exercise group p = 0.001, control group p = 0.035). Due to its positive impact on the pelvic floor, this exercise program should be recommended to women after natural childbirth.