Employing a Laser Headlight Electrical System to Measure and Calculate Electro-Optic Conversion Efficiencies of Blue-Beam Laser Diodes
Round 1
Reviewer 1 Report
The Authors gave a laser headlight electrical system, which was developed and implemented to measure and compare the electro-optic characteristics of the blue-beam laser diodes (BBLDs). This is a quite interesting paper to characterization laser diodes use the potential application in Vehicle headlights. But it still has some points that need the author to indicate and explain the following.
1. Based on the real vehicle headlight, the blue lighting is a not suitable wavelength for application, most use white, yellow, and red lighting. Why did the author use blue laser diodes, not use other color laser diodes directly?
2. In Fig.8, 10,11,13,15,16,18, the BBLD1 should more efficient than BBLD2 and BBLD3 in different drive methods. Do these different from laser diodes or LHES system design?
3. Further, authors need to give the discussion the comparison of average-current modulation and PDCM, which one more efficient, stable, and long operation time?
Author Response
The Authors gave a laser headlight electrical system, which was developed and implemented to measure and compare the electro-optic characteristics of the blue-beam laser diodes (BBLDs). This is a quite interesting paper to characterization laser diodes use the potential application in Vehicle headlights. But it still has some points that need the author to indicate and explain the following.
Response: Many thanks for you to give me an opportunity to modify my manuscript drawbacks. Please review this new manuscript.
1.Based on the real vehicle headlight, the blue lighting is a not suitable wavelength for application, most use white, yellow, and red lighting. Why did the author use blue laser diodes, not use other color laser diodes directly?
Response: Please see the new manuscript on pages 1, 3, 21, and 22.
General vehicle headlights equip with a high beam, low beam, and indication light.
A laser beam has several excellent optical characteristics, such as high color purity, high directionality, high coherency. Therefore, several optoelectronic semiconductor manufacturers have been developing laser diodes of high current density for the optical output power (OOP) laser diodes. Several manufacturers, including BMW, Audi, and SHARP, have invested in the development of laser headlights [4–7]. A few articles have discussed laser headlights for vehicles, with [8] being one of such articles. From the introduction of [8], the four laser diodes can emit the blue laser beams to project on the yellow fluorescence, hence the white light can be produced using this light-mixing technology.
This study developed and implemented a laser headlight electrical system (LHES) to drive and control the laser diodes of the blue beams. The blue laser beams can project on a yellow fluorescence ceramic wafer to transform into white light as the high-beam of the headlight.
Figure 25 presents the developed LHES. As shown in Figure 25(a), the LHES included the human–machine interface, USB/CAN-bus interface, acid-lead battery, LHES, BBLDs, and yellow fluorescence ceramic wafer. When the LHES was operated to drive and control the three BBLDs, laser beams can project on a yellow fluorescence ceramic wafer; therefore, the blue laser beams transformed into white light, as shown in Figure 25(b).
2.In Fig.8, 10,11,13,15,16,18, the BBLD1 should more efficient than BBLD2 and BBLD3 in different drive methods. Do these different from laser diodes or LHES system design?
Response: Please see the new manuscript on page 9.
No, the three BBLDs were driven by an LHES.
The measurement system is depicted in Figure 7. The BBLD OOPs at different temperatures can be observed, when the LHES used PDCM of average-current modulation.
Two practical situations influenced the electro-optic characteristic of the BBLD: First, Three BBLDs were connected in series, and the BBLD1, BBLD2, and BBLD3 were the commercial mass productions; although they were the same model number; however, their electrical characteristics were not exactly the same. Second, to measure the electro-optic characteristics of the three BBLDs, the three laser diode modules were placed inside an ambient temperature–testing chamber, the LHES was placed outside an ambient temperature–testing chamber. The outside LHES must connect with the inside three BBLDs using the long conducting wires. The wire resistances of the long conducting wires resulted in voltage drops. Therefore, the different electrical characteristics of BBLDs and conducting wire resistances can influence the electro-optic characteristics of the BBLD1, BBLD2, and BBLD3.
3.Further, authors need to give the discussion the comparison of average-current modulation and PDCM, which one more efficient, stable, and long operation time?
Response: Please review the new manuscript on pages 19 and 20.
According to the above measurements and discussions, the comparisons of the PDCM and average-current modulation are discussed in the following.
- The EOC efficiencies in the low OOPs were excellent using the PDCM.
- The high-frequency PDCM can obtain a smooth EOC efficiency curve.
- Using the PDCM, the EOC efficiencies can be maintained in a stable range, because they were not much difference between the normal and high temperatures (20 and 40 °C).
- Using the average-current modulation, the OOPs following the average-currents presented linear variation (Figure 8).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper is very difficult to read: English must be edited all over the draft and figures are often not sufficiently clear to the reader. No statistics is reported
Author Response
The paper is very difficult to read: English must be edited all over the draft and figures are often not sufficiently clear to the reader. No statistics are reported.
Response: I apologize that the previous manuscript did not provide adequate materials for the publication and many thanks for you to give me an opportunity to modify my manuscript drawbacks.
Please review the headlight in the new manuscript. Several figures have been redrawn and modified, including Figures 2, 3, 22, 23 24, and 25; moreover, incorrect section titles, English grammar, sentences, and contexts have been modified.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Accept the paper in present form
