LED professional: Professor Pan, you are the Vice Chairman & Secretary-General of Subcommittee 3 on Measurement of Light and Radiation within the Standardization Administration of China. Could you tell us about the main aims and goals of this subcommittee?
Professor Pan: This committee is under the standard administration of China. I am the Secretary and Vice chairman responsible for the standardization in China and this work is coordinated with CIE division 2. They have made a lot of technical reports and standards about LED measurements and test methods for LED quality. In China, we have the sub committee and we research the measurement methods for LED products and we also promote our research results and make recommendations to the CIE. Some experts from China have joined the standardization work in the CIE. We also translate CIE documents to Chinese and these are accepted by the standard administration of China.
LED professional: So what you’re saying is that it goes in both directions. The parts that come from the CIE are taken over by the Chinese regulations and you also put your findings in the general regulations of the CIE. Is there a broad common understanding about the importance of different parameters or are there differences in findings for different research areas?
Professor Pan: Usually we coordinate well and we follow CIE very closely. Sometimes China may differ in application areas because the application industry in China evolves very fast and we have a very strong manufacturing system so we may need something new. But CIE is an international organization with many nations and to vote for a standard is not easy.
LED professional: Could you tell us about the General Expert Group of National 863 Program on Solid State Lighting? What is it and what are the responsibilities of this group?
Professor Pan: The government coordinated this and we have 11 top Chinese scientists in this group. We led the development of the solid-state lighting industry and we determined the future of SSL, supported by the government, who gave a lot of funding for the project. We selected research teams in China and then companies, institutes and universities joined the project. We designed challenging topics and criteria and then we selected research teams. Experts were always invited by many organizations, so we also joined the work of CSA, ISA and CIES, which is the Chinese national committee for CIE.
LED professional: You are also CEO and Chief Scientist at Everfine. Could you give us a short overview of the company?
Professor Pan: Everfine is mainly involved in measurement equipment for the LED and the lighting industry. We have a lot of measurement equipment not only for photometry but also electronic measurement devices, including EMC and power supply. We have a very long production line compared with other competitors in Europe, the USA and Japan. The company was founded in 1993 and it was accepted by the stock exchange in 2012. We have more than 500 employees mainly in China, more than 10 times that of our competitors in other countries! We also have divisions in Taiwan and San Francisco.
LED professional: That’s very impressive! Is it correct to say that you also founded the company and brought in the technologies?
Professor Pan: My major was in optical instruments and my specialty also covers electronics and software. So I have a background in mechanics, optics, electronics and software technologies. After leaving university, I started my research institute and then the company. Everything started from research. My main work, so far, has focused on technical issues. I love to learn new technologies and design on my own and I’ve now joined the activities of international standardization.
I also studied Management and Economics at university. So I know how to run a business and how to encourage a team. I was a guest researcher at NIST and my colleagues always asked me how I could run a company while working at NIST. The way I do it is: I have a qualified management team in my company and they have their positions and their jobs and work well with one another. My method is that “if three of you agree it means that I agree”. It is quite a democratic process! Teamwork is very important for management especially because I want to have enough time to focus on my research and technologies. I have three assistants and their job is to write down my inventions and file patents.
LED professional: How many patents have you filed?
Professor Pan: We have filed more than a hundred patents. More than half of this industry worldwide!
LED professional: Where do you get the inspiration?
Professor Pan: I find my way in my “thinking laboratory”. Sometimes my colleagues want to do experiments in a laboratory but I say that you have to prepare everything in your mind first. If the design is not good and if your job is not well done, experiments may give you a false result. Experiments might be wrong. So we have to think it over. If your logic is strong enough and you have good background knowledge, it will help you very much. My own deep physics background helps me to think of designs and other things in my “thinking laboratory”. It is very important and low cost!
LED professional: You have a very deep insight into technology and research. With the LED, some requirements and measurements change dramatically and new regulations require that you combine the electronic measurements with the light measurement. What is your experience with this trend?
Professor Pan: This is a very important question. I have found that many companies say they are “professional” so they only research the optics or the electronic parameters or only measure thermal issues. I think these are strongly related to each other and if you can see all these problems, you can combine them and find a solution for all the aspects – not just optics but also electronic and thermal. We face many challenges for LED measurement because changing the temperature means thermal dependence and we have to control the electrical parameters. So we need an overall solution. In the past when we measured the thermal parameters we forgot about the optical parameters and output optical power, because this power doesn’t influence thermal parameters. The thermal parameters are only from the electronic power converted to heat and therefore influencing the LED. So we have to measure the optical power and electronic power and then analyze its thermal performance. It should be a compact solution. So I think the total solution is very important and this is the new challenge for the measurement of LED performance.
LED professional: There are different demands on LED products based on their application. Can the new goniospectroradiometer be used both in research and production lines? How are demands different in these two areas?
Professor Pan: I have given two recommendations to the CIE. The first one is that we need a new document for measurement of LED luminaires because these are quite different to the traditional approach. The traditional is only the fixture but the LED combines it, also including the lamp itself. So the measurement method should be changed. The other recommendation is that I think now we should not only measure the luminance intensity distribution of the LED. We also have to measure its spectral qualities. For traditional light, usually the spectrum distribution in different angles is the same. But for LED it is not. The color is not uniform. So we have to measure it. We have many solutions for LED measurement and finally I have found a new solution that can solve all the optical measurement problems. So I recommended that the CIE have such a new document. In 2011, the CIE agreed to have such a new technical quantity and I was selected as a chair for this area. A draft has now been prepared and we hope that the document will be published in 2015-2016. This is a very important area because if we have the goniospectralradiometric information, we have all the information of a luminaire.
LED professional: With measurement requirements there are always different and sometimes contradictory needs based on application and user needs. What are the contrary requirements depending on the users? And how are they overcome or met?
Professor Pan: The spectroradiometer was widely applied both in industry and in the laboratory but for laboratories there is a very high accuracy requirement and the stray light level is the key performance for the spectroradiometer. We have a total solution for this performance. We combine the modified NIST correction method and band pass filter wheel technology. This was also in my presentation at LpS 2014. We have many application groups and the performance is almost equal to the double monochromator level. This kind of high accuracy device can also be applied in production lines because the measurement speed can also be very fast! I think the high accuracy array spectroradiometer can be widely applied in the LED industry and the laboratory.
LED professional: Is there any significant trade off of other parameters?
Professor Pan: I think the cost is a little higher for these spectroradiometers but this is the advantage of a Chinese company, because we have a lot more customers. In China we have more than 10,000 LED companies! So we have a lot of opportunity to have bigger engineering teams with more experience, more skills and more opportunity to invest and develop our technology. Our research costs and our manufacturing costs can be lower and our performance-to-price ratio can be very competitive!
LED professional: A European company told us that they wanted to buy a sphere for measurement modules and they told us that only Everfine was able to provide it. They wanted a maximum diffused reflection and they said you used a nano-technology approach. Is that right and what is this approach/coating?
Professor Pan: The most important thing is that the coating should be non-selective with almost ideal Lambertian performance and it should be stable for a long time. Because inside the sphere, if the reflectance changes a little, the output of the signal changes a lot so the stability is very important. It was not nano-technology but it is special for Everfine.
LED professional: You mentioned new standards and global drafts that you are involved in. What are the key parameters defining the measurement market and how will new standards affect the businesses?
Professor Pan: I think the standard for existing products is not enough and the international societies are fighting for that. For new applications, the LED market and its applications are just at the beginning because everything we see is only replacing traditional lights. Actually, this is not a new LED application. We have to move forward. In China, as the expert group, we promote innovative applications for LEDs and for new innovative applications; we need new standards, methods and measurement equipment.
LED professional: 2015 is the International Year of Light. What are your expectations for it and are there any national initiatives in China?
Professor Pan: CIE and other key organizations have joined this initiative and China has also joined. There will be many activities happening and my company will open our laboratories to the public for a period of time. We are now promoting this and hoping that more organizations will open labs to the public to tell them about the lighting industry. This could be quite meaningful for the general public.
LED professional: You are at the LED professional Symposium+Expo 2014 for the first time. You presented a paper and also have a booth for your company, Everfine. What are your impressions?
Professor Pan: I feel that Bregenz is a beautiful place and the LpS has been organized very well with so many professional people here. This is very important. Many key scientists and engineers are gathered here and some of them are very active in CIE and IEC and I think the attendees are very high level and professional. This is very good!
LED professional: Professor Pan, thank you very much for your time and this very interesting talk.
Professor Pan: Thank you.
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