Professor Cheung Nai-ho (left) and Dr Bruno Cai (right) demonstrate using the patented laser technique to analyse the chemical information of cinnabars on a Chinese painting.


張迺豪教授(左)及蔡鉞博士(右)示範使用新專利技術分析中國畫上硃砂印的化學成份。

Date: 17 Dec 2015 (Thursday)

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HKBU invents patented laser technology for artwork and antique authentication

浸大新創激光技術鑑定藝術品及古董     新技術已獲美國專利

Professor Cheung Nai-ho of the Department of Physics and his former PhD student Dr Bruno Cai have developed a laser technique that can sensitively analyse the chemistry of artwork such as antiques and paintings. Unlike conventional laser ablative microprobes, their technique causes no visible damage to artwork even under high-magnification microscope. The new method measures the chemical information in real-time and achieves 100 to 1,000 times better sensitivity than current methods. The technology has been granted a US patent and the team has set up a company to collaborate with local as well as overseas museums/institutes and private collectors to analyse paintings, ceramics, frescoes and other art objects.

Zep2Probe, the instrumentation platform developed by the team, delivers a laser pulse onto the sample and vaporises about one nanogram of the material. The gas plume so produced is excited to fluoresce by another ultra-violet laser pulse. The fluorescence reveals the elemental composition of the sample.

Professor Cheung Nai-ho said, “Conventional laser microprobes typically remove micrograms of material from the artwork surface. This causes visible and irreversible damage to the sample. Using the new technology, only one nanogram or less of the material is vaporised for detection. Damage will not be visible even when examined under a microscope. The fluorescence signal is then analysed by comparing it against our proprietary database to trace the provenance of the artwork.”

Using the detection of silicon in colour pigments as an example, conventional laser microprobes such as laser-induced breakdown spectroscopy require about one picogram (10-12 g) of silicon in the vapour plume to register a signal while the new technology requires only one femtogram (10-15 g).

Dr Bruno Cai said, “Our team is collaborating with local and overseas partners such as museums to analyse pigments on paintings as well as ceramic artefacts. Specific examples include the analysis of Chinese black inks and cinnabars on xuan paper and the chemical sorting of Yixing teaware. The technology can also be used in the forensic analysis of questioned documents.”

Please click here to see the damage comparison after using conventional laser-induced breakdown spectroscopy (LIBS) and patented technology plume laser-excited atomic fluorescence (PLEAF) on cinnabars (above) and laser printed ink (below).

物理系張迺豪教授與他的博士畢業生蔡鉞博士,研究出一項高靈敏度、可鑑定古董及油畫等藝術品的化學組成的激光技術。與傳統的激光顯微探針比較,新技術在高倍顯微鏡下亦見不到明顯破損。此外,新技術可實時量度其化學成份,比現時常用的方法靈敏度高100至1,000倍。新技術已獲美國授予專利,團隊已成立一個公司,協助本地及海外博物館/協會、私人收藏家等分析鑑定油畫、陶瓷製品、壁畫及其他藝術品等。

團隊研究的「Zep2Probe」儀器把激光射在藝術樣品上,將表面約一納克的物質蒸發。此蒸氣「氣團」受另一種紫外線激光觸發而發出熒光訊號,從熒光訊號顯示樣品的化學元素成份。

張迺豪教授說:「傳統使用顯微探針的方法一般需取得藝術品表面數微克的物質,會對樣品造成明顯、不可修復的破損。新技術下,只需取得不足一納克的樣品,蒸發並檢測,即使用顯微鏡也見不到藝術品有明顯破損。檢測出的熒光訊號與專屬數據庫比較,便可追溯該藝術品的來源。」

以分析顏料中的矽元素為例,一般激光顯微探針如激光誘導擊穿光譜技術,需取得約10-12克(皮克)的蒸氣「氣團」矽作檢測訊號,新技術則只需取10-15克(飛克)便足夠。

蔡鉞博士說:「我們的團隊正與本地及海外伙伴如博物館等合作,協助畫作的顏料分析、鑑定陶瓷贗品等,具體應用包括分析宣紙上的墨和硃砂印,以及紫砂茶壺的化學分析。新技術也可應用於鑑證具爭議的文件。」

按此說明使用一般激光誘導擊穿光譜技術(LIBS)與專利的激光誘導氣團螢光分析(PLEAF)技術在硃砂(上圖)和雷射打印墨(下圖)的差別。