Irradiance uniformity is an important parameter for a Photodynamic Therapy(PDT)device.The calibration and verification of a LED array light source based on computer vision technology were implemented and carried out.F...Irradiance uniformity is an important parameter for a Photodynamic Therapy(PDT)device.The calibration and verification of a LED array light source based on computer vision technology were implemented and carried out.First,the correlation coe±cients between the pulse width modulate value and the irradiance were calibrated.Then,the correction of the actual light center and divergence angle were solved by image processing to reduce errors from each LED lens.Finally,uniformity was optimized according to the irradiance formula of the Lambertian source.The lowest coe±cients of variation of irradiance were 4.87%in a 5 cm×12 cm area and 3.55%in a 3 cm×10 cm area within the depth range of 8–12 cm when the expected irradiance was 100 mW/cm^(2).This finding indicated that the light source can achieve a more uniform illumination and provide a better therapeutic effect for the PDT of port-wine stains.展开更多
Purpose The High energy cosmic-radiation detection facility(HERD)is a space astronomy and particle astrophysics experiment planned to be installed on the Chinese space station.The core detector of HERD,a three-dimensi...Purpose The High energy cosmic-radiation detection facility(HERD)is a space astronomy and particle astrophysics experiment planned to be installed on the Chinese space station.The core detector of HERD,a three-dimensional imaging calorimeter,uses LYSO crystals as the detection medium,with wavelength-shifting fibers readout by image intensifier and CMOS imaging chips.In order to monitor the performance of the calorimeter in orbit,a highly integrated calibration light source subsystem is required to test the pulse linearity of the readout system,including the optical fibers.Method To meet this critical requirement,a Calibration Light Source Subsystem was proposed based on the dual-light-source method,and a test circuit was set up to prove the principle.Results and conclusions Using a photomultiplier tube and waveform sampling module,the entire system’s linear response range was measured,which is equivalent to 1–900 Minimum Ionizing Particles(MIPs),with a linearity better than±5%.After adding an attenuator(transmittance of 6%)to the front end of the photomultiplier tube,the linear response range expands to 14–28,000 MIPs with a linearity better than±5%.This result demonstrated the significant contribution of the PMT’s saturation to the linearity measurement.The addition of the attenuator reduces the adverse effects of PMT saturation,and therefore the linearity of the Calibration Light Source Subsystem itself is better than±5%within the required dynamic range.In addition,testing of a single light source showed that long-term stability can be maintained within a range of±0.5%under conditions of 10–20℃.The calibration method described in this paper has the characteristics of high integration and independent control of channels,providing an efficient and flexible calibration solution for the readout of calorimeter in HERD experiment.展开更多
基金This research was supported by the National Natural Science Foundation of China(Grant No.81773349).
文摘Irradiance uniformity is an important parameter for a Photodynamic Therapy(PDT)device.The calibration and verification of a LED array light source based on computer vision technology were implemented and carried out.First,the correlation coe±cients between the pulse width modulate value and the irradiance were calibrated.Then,the correction of the actual light center and divergence angle were solved by image processing to reduce errors from each LED lens.Finally,uniformity was optimized according to the irradiance formula of the Lambertian source.The lowest coe±cients of variation of irradiance were 4.87%in a 5 cm×12 cm area and 3.55%in a 3 cm×10 cm area within the depth range of 8–12 cm when the expected irradiance was 100 mW/cm^(2).This finding indicated that the light source can achieve a more uniform illumination and provide a better therapeutic effect for the PDT of port-wine stains.
基金supported by the National Natural Science Foundation of China(Grant No.12027803).
文摘Purpose The High energy cosmic-radiation detection facility(HERD)is a space astronomy and particle astrophysics experiment planned to be installed on the Chinese space station.The core detector of HERD,a three-dimensional imaging calorimeter,uses LYSO crystals as the detection medium,with wavelength-shifting fibers readout by image intensifier and CMOS imaging chips.In order to monitor the performance of the calorimeter in orbit,a highly integrated calibration light source subsystem is required to test the pulse linearity of the readout system,including the optical fibers.Method To meet this critical requirement,a Calibration Light Source Subsystem was proposed based on the dual-light-source method,and a test circuit was set up to prove the principle.Results and conclusions Using a photomultiplier tube and waveform sampling module,the entire system’s linear response range was measured,which is equivalent to 1–900 Minimum Ionizing Particles(MIPs),with a linearity better than±5%.After adding an attenuator(transmittance of 6%)to the front end of the photomultiplier tube,the linear response range expands to 14–28,000 MIPs with a linearity better than±5%.This result demonstrated the significant contribution of the PMT’s saturation to the linearity measurement.The addition of the attenuator reduces the adverse effects of PMT saturation,and therefore the linearity of the Calibration Light Source Subsystem itself is better than±5%within the required dynamic range.In addition,testing of a single light source showed that long-term stability can be maintained within a range of±0.5%under conditions of 10–20℃.The calibration method described in this paper has the characteristics of high integration and independent control of channels,providing an efficient and flexible calibration solution for the readout of calorimeter in HERD experiment.
