Tuesday, 20 July 2021

Quote-unquote

When reworking my Invisible Light web site (link here) I decided to include a few quotes that seemed relevant for the subject of infrared photography.

One, I copied from Walter Clark's Photography by Infrared and which comes from William Henry Fox Talbot, in his 1844 book The Pencil of Nature.

... the eye of the camera would see plainly where the human eye would find nothing but darkness.

It's likely that Fox Talbot was aware of Herschel's discovery of infrared about 20 years earlier but whether he's thinking of this, or just of generally being able to see something otherwise invisible, I don't know. The current legal definition of a photograph includes any image using any form of radiation that can be made visible, so does not just include the visible spectrum.

It is difficult, if not impossible, to determine exactly when it was realised that what you see is not all that you get, at least when it comes to the electromagnetic spectrum. Certainly, the remarkable Émilie du Châtelet, in her 1738 paper called Dissertation sur la nature et la propagation du feu suggested that

... there are other colours [emitted by stars] in Nature than those we know in our world.

Although such colours would turn out to be invisible. The simple French belies the significance of the idea.

Il est très-possible que dans d'autres systêmes, il y ait des Soleils qui projectant plus de rayons rouges, verds, &c. que les couleurs primitives des Soleils que nous ne voyons point soient différentes des nòtres, & qu'il y ait enfin dans la Nature d'autres couleurs que cells que nous connissons dans notre monde.

William Herschel in his paper Investigation of the Powers of the Prismatic Colours in 1800 is probably the first to give a name to these new rays ...

... radiant heat will at least partly, if not chiefly, consist, if I may be permitted the expression, of invisible light.

The first use of the term infra-red that I tracked down (via the OED, where else) is from 1881 in Nature; a lecture on solar physics by Captain (later Sir) William de Wiveleslie Abney.

HP Lovecraft, in his 1924 story From Beyond, was somewhat more worried about what might be revealed than Herschel or Fox Talbot ...

With five feeble senses we pretend to comprehend the boundlessly complex cosmos, yet other beings with wider, stronger, or different range of senses might not only see very differently the things we see, but might see and study whole worlds of matter, energy, and life which lie close at hand yet can never be detected with the senses we have.

Roger W Hicks in his 1992 book Successful black-and-white Photography: A practical Handbook was not too fond of the medium.

Apart from its novelty value, I cannot see much reason to use infra-red film other than for scientific purposes. When you have seen a few infra-red pictures, you have seen the lot.

He's not alone: even Ansel Adams was sceptical though he did admit it could work in the right "imaginative" hands.

My favourite, to finish and to contradict HP Lovecraft,  comes from a book about early television, by Ronald F Tiltman in 1927. He has a chapter on Logie Baird's infrared television system, Noctovision, and says ...

Infra-red rays…are quite well-known and highly respectable rays, and have no connection with any much-talked-of death ray or other mysterious rays.

Monday, 28 June 2021

Through a glass not-so-darkly ... infrared to visible up-conversion

I've been familiar with the phenomenon whereby two waveforms can interact such that a third and fourth, the sum and difference of the two wavelengths, are generated. This has been used in radio transmission and reception for decades, known as heterodyning. [See the Wikipedia page.]

I now discover that there is a similar phenomenon at light wavelengths which can result in up-conversion allowing near infrared (AKA short wavelength infrared - SWIR) to become visible. The earliest reference would appear to be in a 1967 paper by JE Midwinter and J Warner [Up‐Conversion of Near Infrared to Visible Radiation in Lithium‐meta‐Niobate Journal of Applied Physics 38, 519].

The abstract is as follows ...

Single‐crystal lithium niobate pumped with pulsed ruby‐laser radiation has been used to convert 1.7‐μ radiation to green light with more than 1% efficiency. A narrow infrared bandwidth of 17 Å, set by the phase‐matching requirement only, allows the up‐converter and photomultiplier to operate in place of a monochromator and infrared detector, and the emission spectrum of a mercury lamp has been thus examined in the region of 1.7 μ. A close agreement between theory and practice has been found in all respects except noise performance. Further studies of this aspect are required.

Moving on to mid-June 2021 and we can see that 'further studies' have indeed been done. (This is not so say that Midwinter et al have not been hard at work; I am coming into this rather late.) The NanoWerk web site has published an article entitled Let there be light! New tech allows people to see in the dark. [Link to the article here.] It outlines how a team at the Australian National University (ANU), working with an international team, have prototyped a device, based on nano-technology and metamaterials, which up-converts near infrared to visible wavelengths.

The lead researcher Dr Rocio Camacho Morales, is quoted in the article saying

We’ve made a very thin film, consisting of nanoscale crystals, hundreds of times thinner than a human hair, that can be directly applied to glasses and acts as a filter, allowing you to see in the darkness of the night.

Fortunately, their paper describing the work is openly available online. The title is Infrared upconversion imaging in nonlinear metasurfaces and describes the technique as follows:

In this approach, the IR image is not directly detected; instead, a parametric nonlinear optical process is employed to convert the image to higher frequencies and detect it using regular cameras in a process known as upconversion IR imaging.

So basically what we have here, albeit in rudimentary form, is a piece of 'glass' that shifts the wavelength of radiation passing through from near infrared to visible light without needing cooling or even imaging technology. There are nanoscale antennas on a gallium arsenide wafer, tuned to the relevant wavelengths and what is described as a pump laser beam to interact with the incoming signal (both near infrared). The frequency of the derived waveform is the sum of the target image frequency and the pump laser beam. This process is also very fast, described as having 'femtosecond temporal resolution' which could enable 'ultrafast imaging of chemical reactions in a conventional microscope device', never mind the opportunities for inexpensive imaging of near infrared. I assume it would work at thermal wavelengths with the right wavelength of pump laser.

Check out the paper and see what you think. I'm fairly excited by the possibilities, even if it will presumably take the team a while to get it to photographic resolutions.

I will finish with their abstract, followed by the citation and link.

Infrared imaging is a crucial technique in a multitude of applications, including night vision, autonomous vehicle navigation, optical tomography, and food quality control. Conventional infrared imaging technologies, however, require the use of materials such as narrow bandgap semiconductors, which are sensitive to thermal noise and often require cryogenic cooling. We demonstrate a compact all-optical alternative to perform infrared imaging in a metasurface composed of GaAs semiconductor nanoantennas, using a nonlinear wave-mixing process. We experimentally show the upconversion of short-wave infrared wavelengths via the coherent parametric process of sum-frequency generation. In this process, an infrared image of a target is mixed inside the metasurface with a strong pump beam, translating the image from the infrared to the visible in a nanoscale ultrathin imaging device. Our results open up new opportunities for the development of compact infrared imaging devices with applications in infrared vision and life sciences.

[Rocio Camacho-Morales, Davide Rocco, Lei Xu, Valerio Flavio Gili, Nikolay Dimitrov, Lyubomir Stoyanov, Zhonghua Ma, Andrei Komar, Mykhaylo Lysevych, Fouad Karouta, Alexander A. Dreischuh, Hark Hoe H. Tan, Giuseppe Leo, Costantino De Angelis, Chennupati Jagadish, Andrey E. Miroshnichenko, Mohsen Rahmani, Dragomir N. Neshev, "Infrared upconversion imaging in nonlinear metasurfaces," Adv. Photon. 3(3) 036002 (14 June 2021) ]

doi.org/10.1117/1.AP.3.3.036002.

Tuesday, 23 February 2021

RPS On-location infrared workshop in May

The Landscape Group of the Royal Photographic Society have organised a workshop in the south of Suffolk to explore and expand your skills in infrared photography with photographer Justin Minns. The locations include Freston Tower and the banks of the River Stour. It's for up to six people and as of today there are still places available.

Prices are £69 for non-members, £52 for members of the RPS and £42 for members of the RPS Landscape Group.

More info on the RPS web site at rps.org/landscape-magicofinfrared.

Saturday, 23 January 2021

Elliott Landy colour infrareds on sale

Elliott Landy, the American photographer, is famous for his images shot at the Woodstock festival and of Bob Dylan and of the Band. He includes infrared photography in his work, and his photo of Dylan was the highlight of my Infrared 100 exhibition in Bath in 2010.

Elliott is holding a sale of some of his colour infrared photographs, running until February 15th. He says:

I consider this body of Infrared Photos to be among my best work from the Sixties. Except for the one of Bob Dylan, people have overlooked these when collecting my work. The prints on sale were shot on Infrared Color Film in the late Sixties except for the ones of Janis Joplin and Richard Manuel in performance which I am including in this group because they share the same visual vibration, or feeling, of the infrareds.

You can find out more on his web site here: www.elliottlandy.com/valentines-day-infrared-print-sale

You'll see that two of the shots, of Janis Joplin and Richard Manuel in performance, are not infrared but have the same vibe. He refers to the film he used as Aero slide film, which is basically the same as the Ektachrome. At the time of these shots I think it was an older formulation which needed a very obscure development process known as E4. I used this version on occasion and had to mail it off to a medical photographers in Harley Street, London, for development. The later E6 version was a lot easier to use and develop.

The photographs on this page are of jazz musician Ornette Coleman and his son, shot in New York in 1969. Though they use the same film, the filter used is different, producing the varied colour effects. To some extent these are unpredictable when you shoot, part of the 'fun' of using that kind of film stock. They are included in the sale. [Photographs are copyright © Elliott Landy used with permission]

Wednesday, 20 January 2021

Life in Another Light

 I have mentioned Kolari Vision before. I used their Chrome infrared colour filter during my test shoot of various ways of filtering a digital camera for infrared photography. Yesterday I saw a photo piece in the Guardian about Kolari's competition called Life in Another Light, which includes various infrared categories and has resulted in some really amazing images. The Guardian shows some of the best ones but the Kolari page (although it loads somewhat slowly for me) also gives information about how they were shot ... and has lots more photos.

You should note that not all the photographs use infrared techniques. That isn't really clear in the Guardian but it is clear in the Kolari page.

One thing I think is proved here is that an infrared image should also work artistically as a photograph as many of these would be great even without the otherworldliness of IR.

Links:

The Guardian

Kolari Vision