The choice of parameters for laser beams used in the treatment of musculoskeletal diseases is of great importance. First, to reach high penetration depths into biological tissue and, secondly, to achieve the required effects on a molecular level. The penetration depth depends on the wavelength since there are multiple light-absorbing and scattering molecules in tissue with different absorption spectra. The present study is the first comparing the penetration depth of 1064 nm laser light with light of a smaller wavelength (905 nm) using high-fidelity laser measurement technology. Penetration depths in two types of tissue ex vivo (porcine skin and bovine muscle) were investigated. The transmittance of 1064 nm light through both tissue types was consistently higher than of 905 nm light. The largest differences (up to 5.9%) were seen in the upper 10 mm of tissue, while the difference vanished with increasing tissue thickness. Overall, the differences in penetration depth were comparably small. These results may be of relevance in the selection of a certain wavelength in the treatment of musculoskeletal diseases with laser therapy.

There is increasing interest in the application of near-infrared (NIR) laser light for the treatment of various musculoskeletal disorders. The present study thoroughly examined the physical characteristics of laser beams from two different laser therapy devices that are commercially available for the treatment of musculoskeletal disorders. Then, these laser beams were used to measure the penetration depth in various biological tissues from different animal species. The key result of the present study was the finding that for all investigated tissues, most of the initial light energy was lost in the first one to two millimeters, more than 90% of the light energy was absorbed within the first ten millimeters, and there was hardly any light energy left after 15–20 mm of tissue. Furthermore, the investigated laser therapy devices fundamentally differed in several laser beam parameters that can have an influence on how light is transmitted through tissue. Overall, the present study showed that a laser therapy device that is supposed to reach deep layers of tissue for treatments of musculoskeletal disorders should operate with a wavelength between 800 nm and 905 nm, a top-hat beam profile, and it should emit very short pulses with a large peak power.

A typical problem for magnetic surveys with small Unmanned Aerial Systems (sUAS) is the heading error caused by undesired magnetic signals that originate from the aircraft. This can be addressed by suspending the magnetometers on sufficiently long tethers. However, tethered payloads require skilled pilots and are difficult to fly safely. Alternatively, the magnetometer can be fixed on the aircraft. In this case, aircraft magnetic signals are removed from the recordings with a process referred to as magnetic compensation, which requires parameters estimated from calibration flights flown in an area with magnetically low‐gradients prior to the survey. We present open‐source software fully written in Python to process data and compute compensations for two fundamentally different magnetometer systems (scalar and vector). We used the software to compare the precision of two commercially available systems by flying dense grid patterns over a 135 × 150 m area using different suspension configurations. The accuracy of the magnetic recordings is assessed using both standard deviations of the calibration pattern and tie‐line cross‐over differences from the survey. After compensation, the vector magnetometer provides the lowest heading error. However, the magnetic field intensity recovered with this system is relative and needs to be adjusted with absolute data if absolute intensity values are needed. Overall, the highest accuracy of all suspension configurations tested was obtained by fixing the magnetometer 0.5 m below the sUAS onto a self‐built carbon‐fiber frame, which also offered greater stability and allowed fully autonomous flights in a wide range of conditions.

We have developed a method employing an autonomous unmanned aerial system (UAS) to provide a more robust measure of the field terrain correction (FTC) for gravity measurements than is offered by traditional methods. The resolution of digital terrain that is typically available for the United States (10 or 30 m) is too low to adequately estimate the FTC in steep terrain. The FTC corresponds to the innermost zone around the gravity station (e.g., extending to a 68 m radius for the Hayford-Bowie zones A and B) and is most often estimated in the field with the aid of templates and charts that approximate sectors of the terrain as uniform slopes. These techniques can incur significant error if they are not performed by experienced practitioners. In our approach, we dispatch a UAS to collect camera images around the gravity station, which we use to construct a digital elevation model (DEM) of the area with the structure from motion (SfM) method. The resulting DEMs allow us to precisely calculate the FTC. We have developed software to automate most of the procedure, including the autonomous flight and image capturing by the UAS. We have experimented with a variety of flight paths at several sites spanning a range of terrain conditions to determine the most efficient flight characteristics for this application. Selecting field sites with existing light detection and ranging data has enabled us to characterize errors in the DEMs derived from SfM and to assess the trade-offs between flight time, processing time, and accuracy of the resulting FTCs. Our methodology is fast (flight time: 3–4 minutes) and robust, primarily because the UAS flight is automated. It can be used to calculate the FTC of a variety of terrain conditions and delivers results that are much more precise than existing methods that do not make use of high-resolution digital terrain data.

There is increasing interest in the application of near-infrared (NIR) laser light for the treatment of various musculoskeletal disorders. The present study thoroughly examined the physical characteristics of laser beams from two different laser therapy devices that are commercially available for the treatment of musculoskeletal disorders. Then, these laser beams were used to measure the penetration depth in various biological tissues from different animal species. The key result of the present study was the finding that for all investigated tissues, most of the initial light energy was lost in the first one to two millimeters, more than 90% of the light energy was absorbed within the first ten millimeters, and there was hardly any light energy left after 15 – 20 mm of tissue. Furthermore, the investigated laser therapy devices fundamentally differed in several laser beam parameters that can have an influence on how light is transmitted through tissue. Overall, the present study showed that a laser therapy device that is supposed to reach deep layers of tissue for treatments of musculoskeletal disorders should operate with a wavelength between 800 nm and 905 nm, a top-hat beam profile, and it should emit very short pulses with a large peak power.

The human brain contains magnetic iron oxide nanoparticles in the form of magnetite (Fe₃O₄); however, the origin and physiological implications of these crystals remain debated. Due to their low concentrations in brain tissue (∼1–20 ng g⁻¹), the identification and characterization of individual magnetic particles require nanometer-scale spatial resolution over large scan volumes. In contrast to conventional electron microscopy techniques that have field of views typically on micron scales, the Quantum Diamond Microscope (QDM), based on wide-field nitrogen-vacancy center imaging, can generate magnetic field maps over areas of several square millimeters while detecting nanoscale particles. Moreover, the QDM can directly quantify the strength and direction of the particles' magnetic moments. Operating the QDM in a high-sensitivity mode, coupled with long acquisition times, enabled the detection of magnetic moments as small as 3 × 10⁻¹⁷ Am², corresponding to a magnetite particle diameter of approximately 50 nm, in maps covering 1.40 × 2.25 mm². This is the highest magnetic moment sensitivity of wide-field magnetic microscopy >1 mm² to date. In addition, collecting repeat, but slightly offset magnetic field maps resulted in the unique ability to distinguish sources within a sample from contamination and artifacts. By applying this technique to tissue, we demonstrate the detection of magnetic dipole-generating sources in human and rodent brain samples with the QDM. Detected particles span a size range of 60–135 nm, consistent with the larger end of magnetite particle sizes found by electron microscopy. These are the first direct magnetic observations of magnetite nanoparticles in brain tissue using quantum sensing techniques.