Ultrasonic Levitator – a powerful tool for contact-free experiments

Ultrasonic Levitator – a powerful tool for contact-free experiments

超声波悬浮器 – 用于微重力实验的强大工具

Tag: Acoustic Levitator 超声波悬浮器, contactless environment 物体悬浮, spectroscopy 光谱仪, microgravity 微重力, tec5 AG

Ever since that Bücks and Müller demonstrated their ultrasonic/ acoustic levitation experiment in 1933[1], this technique has slowly transformed into a powerful and versatile method for the study of droplets or particles in a contactless environment. The basic principle behind this technology is simple:  a sound standing wave is generated between an ultrasonic transducer and a reflector (see Figure 1). Within this standing wave there are several pressure points that could counteract the gravitational force and levitate the samples.  As a rule of thumb, samples with effective diameters of less than half of a wavelength (sound) will be levitated slightly below the pressure modes. When the sample’s size is approx. three times smaller than the sound wavelength, minimal acoustic power is required for the levitation.

自从Bücks和Müller在1933年展示了他们的超声波悬浮实验[1],这个技术慢慢地变成一种用于在非接触环境中研究液滴或颗粒通用的方法,。基本原理很简单:超声驻波在超声波传感器和反射器之间产生(见图1)。 在该驻波内的压力最小点可以抵消重力并悬浮样品。 根据经验,只要样品的有效直径大约小于波长(声音)的一半可以悬浮的。 当样品三倍小于比声波长,悬浮需要最小的声功率。

Attractive features of an ultrasonic levitator:

  • Provide contactless environment
  • Provide controllable gas environment
  • Required a very small sample volume
  • Can be easily combined with numerous analytic techniques, such as FTIR, UV-VIS-NIR, RAMAN spectroscopy, microscopy, X-ray scattering etc.

– 提供无接触环境
– 提供可控的气体环境
– 只需要非常小的样品体积
– 可以很容易地结合众多的分析技术,如FTIR,紫外-可見光-近红外光谱仪,拉曼光谱,显微镜,X射线散射等。


Figure 1: Left: Levitated droplet at the pressure node. Right: Schematic drawing of the ultrasound resonator.

Application Examples 应用示例

CASE 1: The study of nanomaterial self-assembly using ultrasonic levitator and X-ray 使用超声波悬浮器和X射线研纳米材料自组装

Seddon et al. and his coworker [2] have successfully demonstrated the levitation of soft nanomaterials and analyze them under contactless manner. In addition, they implemented the in-situ X-ray scattering (SAXS) as well as controllable gas-phase environment to study the crystalline phase of the investigated nanomaterials. Their study has shown that such a technique open -up new experimental approaches for study of materials without wall effect.

Seddon和他的同事 [2] 已经成功地悬浮了软纳米材料的,并以非接触方式分析它们。 此外,他们实施原位X射线散射(SAXS)以及可控的气相环境,研究纳米材料的结晶相。 他们的研究表明,这种技术开辟了新的实验方法来研究材料。


Figure 2:  A setup for investigating the nanomaterial self-assembly within in a controlled gas phase and contract free environment [2]

Few month later Agthe group [3] uses the similar setup to perform the study of nanoparticles assembly into mesocrystals (see Figure 3). The experiment demonstrates how the crystallization process of a levitated nanocubes proceed using small angle X-ray scattering and ex situ scanning electron microscopy.

几个月后Agthe组[3]使用类似的设置来研究纳米颗粒如何组装到介晶(见图3)。 他们还使用小角度X射线散射和扫描电子显微镜调查悬浮纳米颗粒的结晶过程。


Figure 3:  a) Schematic drawing of the experimental setup using ultrasonic levitator, camera and D-rays to study the assembly of levitated nanoparticles b-f) show the SAXS and SEM results [3].

Case 2: The study of droplet evaporation using ultrasonic levitator and heater/cooler使用超声波悬浮器和加热器/冷却器研液滴的蒸发

Yan [4] has performed an interesting study using the ultrasonic levitator together with a heater/cooler. The goal was to study the freezing/melting of a droplet/ice suspended in air. This experiment has successfully investigated the relationships between percentage melting states of water droplets for varying residence times.

Yan[4]使用超声波悬浮器和加热器/冷却器进行了一项有趣的试验。 目的是研究悬浮在空气中液滴的冻结/熔化/。该实验成功地研究了水滴的熔融百分比和不同停留时间之间的关系


Figure 4. Experimental setup for the study of melting of frozen droplet (ice crystal) suspended in air. 

A similar study was performed by Saha [5] in his PhD thesis (later chapters include the study of agglomeration of nanoparticle). But this time, near infrared and infrared laser is used as the heating source instead. The study has successfully described different stages of evaporation of droplets that contained Nano-suspensions or precursor solution.

Saha [5] 在他的博士论文中进行了类似的研究(后面的章节包括纳米颗粒聚集的研究)。 但这次,近红外和红外激光器被用作加热源。 研究成功地描述了纳米悬浮液或前体溶液滴的蒸发不同阶段。


Figure 5. Experiement setup for the study of levitated droplet’s evaporation via laser heating

Case 3: The study of levitated dye laser 悬浮染料激光

A research group from Denmark [6] has reported a very interesting experiment using an ultrasonic levitator and demonstrate a lasing action in a levitated dye droplet (see Figure 6). In this case, the droplet itself acts as a resonator and a frequency doubled Nd:YAG  laser was used as the optical pump. The laser emission is captured and analyzed by using a spectrometer.

来自丹麦的一个研究小组[6]做了一个非常有趣的实验。他们使用超声悬浮器证明在悬浮染料液滴中能起激光作用(参见图6)。 在这种情况下,液滴本身用作谐振器,并且使用倍频Nd:YAG激光器作为光泵。激光之后使用光谱仪捕获和分析。


Figure 6. Lasing action of a dye droplet suspended in air

Case 4: The study of nanoparticles using ultrasonic levitation combined with various optical spectroscopy techniques 使用超声波悬浮和各种光谱技术研究纳米颗

One of the holy grail for experimentalist is to be able to perform and analyze an untainted specimen using different type analytical tools simultaneously. This has been shown to be possible by Dr. Schenk in his PhD dissertation [7]. Figure 7 shows the schematic drawing of his setup, where he combined different techniques such as RAMAN, UV-VIS and fluorescence spectroscopy in one setup and investigate the levitated samples.

实验者的圣杯之一是能够同时使用不同类型的工具析未受污染的样本。 这已经被Schenk博士在他的博士论文 [7]中证明是可能的。 图7显示了他的设置示意图,他在一个设置中结合了不同的技术,如拉曼,UV-VIS和荧光光谱,并研究悬浮样品。


Figure 7. Schematic drawing of a levitation setup in combination with RAMAN, UV_VIS and fluoreschence spectroscopy.

Ultrasonic levitator has been proven to be a very useful tool for the study of microfluidic as well as nanomaterials in contact free environment. Such a device is commercially available and can be purchased under: https://www.tec5.com/en/products/custom-solutions/levitator


  • Levitator with transducer frequency of 58 KHz
  • Levitator with transducer frequency of 100 KHz
  • Levitator with integrated free jet Noozle
  • Levitator with Integrated Piezo sensor


超声悬浮体已被证明是非常有用的研究产品。 这样的设备可以在以下网址购买:https://www.tec5.com/en/products/custom-solutions/levitator


  • 传感器频率58 KHz
  • 传感器频率100 KHz
  • 带有集成喷嘴


References :

  1. Bücks, K., Müller, H.: Über einige Beobachtungen und Piezoquarzen schwingenden Ihrem Shallfeld. Z. Phys 84, 75-86 (1933).
  2. Seddon A. M., Richardson et. al.: Control of Nanomaterial Self-Assembly in Ultrasonically Levitated Droplets, J. Phys. Chem. Lett. 2016, 7, 1341−1345
  3. Following in Real Time the Two-Step Assembly of Nanoparticles into Mesocrystals in Levitating Drops. Michael Agthe, Tomás S. Plivelic, Ana Labrador, Lennart Bergström, and German Salazar-Alvare Nano Letters Article
  4. Yan, S. (2016) Experimental impact dynamics testing of a glaciated water drop and quantification of partial melting with varying residence time (Master dissertation). Retrieved from https://etda.libraries.psu.edu/files/final_submissions/12701
  5. Abhishek, S. (2012) Evaporation, Precipitation Dynamics and Instability of Acoustically Levitated Functional Droplets (Doctoral dissertation). Retrieved from https://etd.fcla.edu/CF/CFE0004436/PhD_Asaha_submission.pdf
  6. Azzouz, L. Alkhafadiji, S. Balslev, J. Johansson, N. A. Mortensen, S. Nilsson, and A. Kristensen, “Levitated droplet dye laser,” Opt. Express 14, 4374-4379 (2006)
  7. Jonas, S (2014) Optische Spektroskopie in der Ultraschallfalle (Doctoral dissertation). Retrieved from https://hu-berlin.de/dissertationen/schenk-jonas-2014-10-02/PDF/schenk.pdf



OLED is on fire!



(image source: Shinny plastic)

Even since Samsung achieved great success in the AMOLED display market, china’s panel makers to rush and invest in the OLED technology ( despite the fact that the Chinese government promote the LCD technology. Currently Visionox, Sichuan CCO Display Technology, Truly Optpo-electronics, BOE Technology group, Tianma Micro-electronics , China Star Optoelectronics (CSOT) and EverDisplay all announced massive investment in the OLED display technology. Tablet PCs, near eye virtual reality devices , mobile devices, automotive monitors and OLED TV demand the development of new flexible display technology.

Just how big is OLED business? According to IHS Inc data,  the revenue from flexible displays will increase from $ 3.7 billion @ 2016 to $ 15.5 billion @ 2022 ( 300% !). According to the rumor ( source: the korean Herald), Samsung will supply 100 million units of 5.5-inch OLED panels annual ( $ 2.58 billion deal) to apple.

According to the UBI Research’s OLED Manufacturing Equipment Annual Report, the global Gen6 flexible AMOLED manufacturing equipment market is expected to record USD 28,411 million in 2016-2020. 47% of this is for Apple’s use with USD 13,000 million.


Source: IHS Inc data, OLEDnet.com, macrumors.com







Additive Manufacturing a.k.a 3D printing is on Fire!

Recently the web is bombarded with the news of how the 3D printing is taking over the world! Lots of companies are trying to get piece of the pie, including 3D Systems, Concept Laser, e-Manufacturing Solutions (EOS), Materialise, Matsuura, Realizer, Renshaw, RPM Innovations, SLM Solutions, Stratasys, Sodick, and Trumpf  etc.

Airbus group has just open up an additive manufacturing center in Munich

GE will approx. 39million dollars in a new additive manufacturing center at Pittsburg.

NASA is testing 3D printing technology by manufacturing complex engine parts.

MTU / Airbus will use additive technology to manufacture components.

Source: http://www.industrial-lasers.com/laser-additive-manufacturing.html

NKT Photonics acquires ultrafast fiber laser maker Fianium

To strengthen its position in ultrafast fiber and supercontinuum lasers, NKT Photonics (Birkerød, Denmark) is acquiring Fianium (Southampton, England) in an all-cash transaction woth approximately EUR 27 million. The acquisition will also improve NKT Photonics’ global market position in terms of geographical coverage, manufacturing facilities, and complementary product portfolios.

Source: http://www.laserfocusworld.com/articles/2016/03/nkt-photonics-acquires-ultrafast-fiber-laser-maker-fianium.html

Coherent – Rofin struck with a $942 million deal

Rofin-Sinar Technologies Inc., a laser-products company contending with a harsh proxy fight, has struck a $942 million deal for a sale to Coherent Inc.

The $32.50-a-share deal provides a 42% premium to Rofin-Sinar’s Wednesday closing price of $22.91. Rofin-Sinar shares were slightly above the deal price in recent-after hours trading, rising 44% to $33.

Rofin-Sinar will postpone its annual meeting, which had been scheduled for Thursday.

Coherent expects the deal to close within six to nine months, and expects it to add to earnings per share in the first full year after closing.

Coherent said the purchase will strengthen its position in materials processing. It expects about $30 million of annual savings within 18 to 24 months of closing.

Coherent’s laser products are used for a wide range of applications including defense, graphic arts, life sciences and materials processing. For the year ended Oct. 3, the Santa Clara, Calif., company had net sales of $802.5 million.

Rofin-Sinar, which has operational headquarters in Plymouth, Mich., and Hamburg, Germany, posted net sales of $519.6 million for the year ended Sept. 30. It serves the semiconductor, automotive, machine-tool and solar sectors, among others.

Source: WSJ

How to see around the corner?

Screen Shot 2012-03-21 at 12.06.59 PM

Researchers at Heriot-Watt University in Edinburgh, Scotland have recently developed a super sensitive camera that could detect what is hidden behind the corners. The camera is called single-photon avalanche diode (SPAD) camera and using the photons echo mapping technique, it is possible to see beyond the line of sight!

Actually this technique is really not that new. In 2012, MIT researchers announce that they have developed a camera that can capture trillion frame per second. Using it, it is possible capture the photons that reflected from object or person around the corners.

Cool right ?



Tutorial 102: How to select a f-theta objective for your scanner ?


f-theta objective is normally used together with a galvo-based laser scanner. It has 2 main functions: focus the laser spot and flatten the image field, as shown in the image below. The output beam displacement is equal to f*θ, thus was given the name of f-theta objective. Current leading companies for f-theta objectives includes SILL optics, Jenoptik , LINOS, ULO, II-IV etc.


Left: typical scan field with curvature using single focusing lens. middle: typical result of a flat field lens. Right: flat field objective can provide flat field and f*θ at the output (Source: Thorlabs).

By asking the following questions, it is possible to narrow down the selection of the scanning objectives:

  • What is the laser parameters (wavelength, average power, pulsed or CW?) -> determine the AR coating and the lens materials.
  • What is the required image field size and focused spot size? -> determine required focal length.
  • Is the telecentricity properties of the f-theta objective important? -> determine whether you would need a telecentric lens. For example, drilling application

So what to look at when shopping for a f-theta?

  • focal length
  • output beam quality
  • clear aperture of the objective
  • telecentric or not?
  • lens materials ?
  • achromatic or not?
  • Would thermal shift be an issue ?

In general, a diffraction limited f-theta combined with a scanner would produce a spot size given by:

Spot size (1/e²) = (λ• f • APO • M²) / Dg, where APO is the truncation factor that depend on the ratio between aperture stop of the scanner and input beam diameter. Different ratio will give different APO value, as shown below:

2.0 1.27
1.5 1.41
1.25 1.56
1.0 1.83
0.9 1.99
0.75 2.32
0.5 2.44

As for other Da/Dg ratio, one can estimate the APO using hyperbolic tangential function or the formula stated in  “CVI Melles Griot All things Photonics”

Source: Jenoptik, Sill Optics & Thorlabs


Instead of paying hundreds pf thousands of dollars for a Selective Laser Sintering printer, why not try to build it for $2000 ? Rice University researcher has recently demonstrated that it is possible to develope a low-cost, open-source SLS system (OpenSLS) and demonstrated its capacity to fabricate structures in nylon with sub-millimeter features and overhanging regions.




Laser + Glass – you got yourself a 360GB memory that last for hundred of millions years

Imagine the Superman using his laser beam eye to store information in the memory crystals in the Fortress of Solitude. Too bad,  he cannot create femtosecond pulsed with his eyes.

CW-STM-Fortress-28source: capedwonder

Hitachi has developed a glass-based data storage medium that is highly heat and water resistant, capable of holding data for hundreds of millions of years, and says it may be able to bring it to market by 2015.The company’s main research lab has developed a way to etch digital patterns into robust quartz glass with a laser at a data density that is better than compact discs, then read it using an optical microscope. The data is etched at four different layers in the glass using different focal points of the laser.

The company has tested the durability of the quartz glass it uses and determined that it will last for “hundreds of millions of years.” It said samples held up to two hours of exposure to 2000-degree-Celsius heat in an accelerated aging test. Hitachi said it first conceived of the idea of storing data by etching it into quartz glass in 2009, but read and write times remained an issue. The company uses tiny dot patterns to store bits, and has recently developed a way to etch 100 dots at a time, greatly improving the write time.

Recently the scientists at the University of Southampton have made a major step forward in the development of this digital data storage.Using nanostructured glass, scientists from the University’s Optoelectronics Research Centre (ORC) have developed the recording and retrieval processes of five dimensional (5D) digital data by femtosecond laser writing.

The storage allows unprecedented properties including 360 TB/disc data capacity, thermal stability up to 1,000°C and virtually unlimited lifetime at room temperature (13.8 billion years at 190°C ) opening a new era of eternal data archiving. As a very stable and safe form of portable memory, the technology could be highly useful for organisations with big archives, such as national archives, museums and libraries, to preserve their information and records.

Screen Shot 2016-02-20 at 9.54.08 PM

How does it works?

5D data storage.jpg_SIA_JPG_fit_to_width_INLINE

To record data, spots are imprinted on the glass (pictured below) using a femtosecond laser. A femtosecond laser, in this case, produces bursts of laser light that last for just 280 femtoseconds (280 quadrillionths of a second). These spots, thanks to the nanostructuring of the surface, and some hologram cleverness, are capable of recording up to three bits of data in two “dimensions.” By varying the focus of the laser, the team are able to create layers of dots that are separated by five micrometers (0.005mm) in the z-axis (the third dimension). Then, by simply moving the laser horizontally and vertically, these tri-bits can be stored in two more dimensions, bringing the total to 5D. The image at the top of the story helps illustrate this concept.

To read these spots, an optical microscope that’s capable of untangling the polarized light reflected by the three-bit spots is used. There’s no word on whether these silica glass discs can be rewritten, but the research paper makes it sound like this is a write-once-read-many (WORM) storage method.

Source: University of Southhampton; Extremetech; Hitachi



DOUG AITKEN’S STATION to Station, which took a crew of visual artists and musicians from New York to California aboard a nine-car train, brought together digitized modern creativity and the distinctly analog appeal of the great American road trip. They rode the rails, they performed, they stopped and collaborated with locals, and streamed it all online. Now Aitken has synthesized the three-week experience into a documentary of 62 one-minute highlights,available on iTunes starting Jan. 15.

In the above clip from the documentary, data visualization artist Aaron Koblin (now the CTO of virtual reality company Vrse) explains Light Echoes, the product of a collaboration between himself and director Ben Trickleback. In Koblin’s words, it’s their way of “mapping the history of the train on top of the landscape.” The twist is that their cartography is accomplished with a giant array of lasers projecting images onto train tracks. The vividly colored result is a trail of light that looks as organic as it does alien.