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18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett
Prof Ted Kroon
Prof Ted Kroon from the Department of Physics recently delivered his inaugural lecture on the topic What’s the use of a rainbow on the UFS Bloemfontein Campus.
“A rainbow is a natural phenomenon, the result of the refraction and reflection of the sun’s rays in drops of rain. As far as mankind is concerned, it’s a perfectly useless object and won’t make anyone money. Yet the poet who said, My heart leaps up when I behold a rainbow in the sky, only put into word the feeling of wonder and excitement we all have when we see a rainbow.”

“Every day I see a rainbow in my work; I do not need to wait to see one in the sky,” says Prof Ted Kroon, Professor in the Department of Physics at the University of the Free State (UFS), who used this phenomenon to introduce the topic of his inaugural lecture: What’s the use of a rainbow. 

“Far from being only a colourful spectacle with no practical value, rainbows are useful – and lead to useful things,” he believes. 

According to Prof Kroon, one can find examples of real rainbows and rainbow analogies used not only in everyday life, but also in physics. “Besides it being familiar devices in literature, culture, and even marketing, studies of rainbows can yield practical engineering information and may even help us to find new habitable planets,” he says.

Inspired by the many uses of a rainbow

In his lecture, he discussed the basic features of natural rainbows and how they come about. He also explored how the rainbow gives meaning to colour, and how this relates to the temperature of objects. He looked at an array of instances where the rainbow is used; from depicting the life of a star to indicating that we are sick (a thermometer) or when we need to refill a gas cylinder.
Moreover, Prof Kroon pointed out that rainbows are used in computer chips, stress identification, and to transmit internet data through underwater cables of glass fibre. He also referred to how the rainbow was harnessed as an engineering tool to measure refractive index and characterise fine droplet sprays used in industry. 

He continues, “Remarkably, the science developed to understand the natural rainbow can be redirected and applied to the optical properties of metallic nanoparticles, allowing the development of nanotechnology. Knowing how the natural rainbow works and its limitations, better systems have been developed to produce rainbows. Such rainbows have been used to discover new elements and to determine the age of the universe.”

As a member of an international community of phosphor researchers who are privileged to work with rainbows every day, he has used them to study the light-emitting properties of materials doped with bismuth. With this project – an initiative with the African Laser Centre taking place between 2016 and 2021 – he collaborated with the University of Khartoum in Sudan and trained a number of its postgraduate students. “My role included the guidance of students and the measurement and interpretation of the light-emitting properties of the materials. Our research during this time, considering more than a dozen materials, was summarised in 34 scientific publications that contributed to a greater understanding of bismuth ions as light-emitting materials,” he explains. 

Developing new materials, efficient in emitting blue light

He has been developing luminescent materials since 2006, primarily for general lighting (fluorescent tubes and LEDs) and displays (television, computer, and cellphone screens), as well as niche applications in medical and forensic science. 

As part of his current research, he is examining the effect of plasmonic metal nanoparticles on phosphor light emission. He is also exploring materials that absorb infrared light but emit visible light. “For this, I would like to consider the long-term stability of such materials and develop new materials that are more efficient in emitting particularly blue light,” he says. 

Prof Kroon holds a C2 rating from the National Research Foundation and has published more than 150 articles and book chapters, obtaining a Scopus h-index of 26.

News Archive

Access to the Bloemfontein Campus
2015-04-02

Access Control Made Easy

The first phase of access control at the University of the Free State (UFS) was implemented in August 2014. The aim of this initiative is to tighten security measures on the Bloemfontein Campus.
 
Since November 2014, access control has been implemented at all five gates on the Bloemfontein Campus. These are:

  • The Main gate in Nelson Mandela Drive (Gate 1)
  • The gate in DF Malherbe Drive (Gate 5)
  • The gate in Wynand Mouton Drive (Gate 3) 
  • The gate in Furstenburg Street (Gate 4)
  • The gate in Badenhorst Street (Gate 2)

Here is some useful information about the access control system:

1. Remember your access card when you enter the campus

Dual-function cards (with distance reader compatibility) will make your movement through the gates more convenient. The university’s access system works automatically with remote or swipe action. Please make sure that you drive close to the reader or, better still, get the dual-frequency card to manage the distance between your vehicle and the remote card reader.

As of 23 March 2015, the extra security staff, who have been assisting at the gates since the implementation of access control on the Bloemfontein Campus, are no longer manning the card readers at the gates. Therefore, persons without cards will be able to enter the campus only at the one gate in DF Malherbe Drive where the Visitors Centre is situated. They will be referred to the Visitors Centre, where a day visitor’s card will be issued to them. You will need to produce a formal identification document (e.g. ID book, driver's licence).

Security will continue their normal duties at the guardhouses for the various gates on the campus.

2. Where do I get an access card?

You can apply at the university’s Visitors Centre front desk by producing your positive identification (ID book/passport/driver’s licence) and proof of payment for your access card.

You will then be directed to the Thakaneng Bridge where you will be able to collect your access card.

  • Go to the Cashier on the Thakaneng Bridge and pay your R65 for the dual-frequency card
  • Take your receipt, together with your existing card (if you have one), to the Card Division on the Thakaneng Bridge (next to Mellins Optometrists)
  • A new photo will be taken of you at the Card Office for your new card. Your new card will then be issued immediately.

Currently, there is a sufficient stock of the dual-frequency cards available at the Card Division on the Thakaneng Bridge.
 
Alternatively, you can apply online for your access card: http://apps.ufs.ac.za/cardapplication/application.aspx

Make sure you have the following documents ready to attach when completing the online form:

  • Copy of positive identification: ID/Driver's Licence/Passport
  • Signed declaration (http://supportservices.ufs.ac.za/dl/Userfiles/Documents/00007/4668_eng.pdf) by your service provider/employer (if you are a service provider) or a letter of confirmation from your spouse/partner/relative/coach/relevant UFS staff member or student in cases where you have to visit, pick-up or drop off your spouse/partner/relative frequently on the UFS Bloemfontein Campus.

Cost: R65 for a long-term card and free of charge for short-term visits and conference delegates. Pay at the Cashier on the Thakaneng Bridge or at Absa Bank, Account Number: 1 570 8500 71, Ref: 1 413 07670 0198.

3. Cutoff Date: 7 April 2015

After 7 April 2015, no pedestrian or motorist will be able to enter the campus without a valid access card. Persons without access cards will have to enter the campus at the gate in DF Malherbe Drive where the Visitors Centre is situated. You will then be referred to the Visitors Centre where you will have to apply for a day visitor’s card. It is important to note that no one will be able to enter the campus at the Visitors Centre without a formal identification document (e.g. ID book, driver's licence).

4. Dual-frequency card simplifies access to the campus

It is important to have your card ready on entering the campus.

This card will simplify access to the campus considerably, as the card reader will read the card when it is held in a vertical position at the driver’s side window in the direction of the distance reader. Please do not place the card on the dashboard. There is an antenna wire in the card. If the card is placed on the dashboard, you are not exposing the card surface to the reader, and that might influence the antenna’s response to the reader.

Remember, the distance between the reader and the boom is only a few metres.  If you approach the reader at a ’high’ speed, you are not allowing the system to identify your card, match it to the entry in the database, check if you are ‘legal’, and then send a signal to open the boom. 

All five gates are equipped with distance readers. Within the next three weeks, two extra distance readers will also be installed at the Main Gate in Nelson Mandela Drive.
 
Please note that the dual-frequency card is needed only when you enter the campus with a vehicle and you want to activate the distance reader. All the older cards will continue to work at the tag readers. 

5. Use alternative gates

At times, some of the gates carry more traffic than others, especially with the peak morning and afternoon traffic. Gates with less traffic include:

  • The gate in Badenhorst Street
  • The gate in DF Malherbe Drive
  • The gate in Nelson Mandela Drive

You are welcome to make use of one of these alternative gates.

6. Pedestrians

No pedestrian will be able to enter the Bloemfontein Campus without a valid access card. If you have left your card at home or have lost it, you should enter the campus at the gate in DF Malherbe Drive where the Visitors Centre is situated. You will be referred to the Visitors Centre where you can apply for a day visitor’s card. You will still need to produce a formal identification document (e.g. ID book, driver's licence).

7. More information

Email: visitorscentre@ufs.ac.za
Visitors Centre front desk: Tel: +27 51 401 7766 (Mondays-Fridays 07:45-16:30)
Card Division: Tel: +27 51 401 2799 (Mondays-Fridays 07:45-16:30)
Protection Services duty room: +27 51 401 2634 (24 hours)

 

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