Pm200 power meter

We roughly evaluate the power density of the UVC afterglow using a Thorlabs PM200 power meter equipped a power sensor (S120VC, Thorlabs). The detailed measurement method is shown in Supplementary Fig. 20. After considering all possible factors that impact the measurement, the initial afterglow power density at the sample position was roughly estimated to be ca. 14.9 mW/m².

Nine Pentero 900 and one Kinevo 900 (Carl Zeiss AG, Oberkochen, Germany) clinical grade operating microscopes routinely used in the hospital operating rooms were assessed. Remaining bulb life time, focus distance, and light intensity settings were recorded from data displayed on the microscope work screen. Experiments were performed in darkened operating rooms. Microscopes were set up at constant distances from the target and incident light intensities were measured using a PM 200 power meter, and S120VC photodiode power sensor (ThorLabs GmbH, Dachau, Germany) calibrated for 405 nm. Optical power measurements were taken at various locations by moving the power meter probe across the round field of view of the microscope. A small aperture (6-mm diameter) was set in front of the power meter sensor to provide better granularity of the optical beam measurements. We recorded the optical power of the standard white light and the blue light in BLUE 400 mode. The zero point of the power meter was adjusted in each operating room before taking measurements to compensate for variations in ambient light.

All images shown were recorded with transiently
transfected HeLa cells 24 h post-transfection. Cells were mounted
in DMEM without phenol red (Thermo Fisher) and imaged at ambient temperature
with a customized 1C RESOLFT QUAD scanning microscope (Abberior Instruments,
Göttingen, Germany). The microscope was equipped with an UPLSAPO
1.4 NA 100× oil immersion objective (Olympus, Shinjuku, Japan)
as well as 405 and 488 nm continuous-wave lasers (both Cobolt, Solna,
Sweden). The 405 nm doughnut-shaped beam was realized with an easy
3D module (Abberior Instruments). Fluorescence was detected with a
SPCM-AQRH-13 photon counting module (Excelitas Technologies, Waltham,
MA, USA) with a HC 550/88 detection filter. Laser powers were measured
behind the objective with a PM200 power meter with the S170C sensor
(ThorLabs, Newton, NJ, USA). The circular or ring-like area of both
beams at FWHM intensity in the focus were determined and used for
further calculations. Images and filament intensity line profiles
measured with three adjacent lines were analyzed with the Fiji distribution
of ImageJ (v1.52p)^{58 (link),59 (link)} and OriginPro 2018b (OriginLab).
This manuscript has been previously submitted to the preprint server
bioRxiv.⁶⁰