Tunablequantum cascadelaser

This quasi-monochromatic nature enables the use of relatively slow, uncooled detectors, that would not be suitable for FT-IR spectroscopy.However, when combined with a QCL, we can take advantage of the full dynamic range of these detectors and detect signals at a single wavelength, resulting in excellent signal-to-noise ratios. This brings us back to the initial question: why use QCLs for spectroscopy? Sure, the better signal-to-noise ratio is a big plus but most importantly, a QCL microscope does not need to record a full IR spectrum for every pixel of the chemical image - unlike its FT-IR counterpart.

For those looking to take their videos and photos to the next level, we've tested a ton of useful tools, from best smartphone gimbals to the top iPhone lenses and best tripods for iPhones as well as our favorite full size-tripods. With your camera phone in your pocket and the best cell phone accessories, you're sure to level up your media production.

No ring lights in our review came close to the light quality the Westcott model offers. Still, of the smaller lights, the UBeesize 10" with Tripod performs better than the rest, with the Sensyne 10" Ring Light with 50" Extendable Tripod following close behind. These 10" ring lights offer 240 lumens and 11 dimmer steps, and 225 lumens and 10 dimmer steps, respectively. Both come with three different warm tones for a cooler or warmer feel.

In case you haven't used many ring lights, we wanted to compare how each light size category affects a portrait. One of the big things is the “catchlights” — if someone uses a ring light, you can almost always see the characteristic circles in their eyes.

The top scorer for stability is the UBeesize 10" Tripod, which proved remarkably sturdy. The Neewer and Westcott models also achieved a high score in this category (like all categories), inspiring confidence with whatever device we needed to use. The Auxiwa Clip-On, Xinbaohong Clip-On, and ShiftCam SnapGrip Creator Kit (to some extent) are also “stable” in the sense they don't require a tripod — they are as stable as your hands are.

To test ring lights, we took hundreds of photos with each of these devices and conducted controlled photo experiments to measure relative brightness. We played with all the different features, timed setups and breakdowns to assess ease of use, and monitored stability by attaching our phones and cameras to each product. We determined the durability by physically comparing each model throughout our testing and digging through online user reviews to find any frequent issues to watch for while testing.

But of course, implementing QCL technology into an IR microscope comes with some technical challenges. First and foremost, the coherent nature of the laser source leads to something called coherence artefacts. These fringes and speckles in IR images and spectra are generally considered harmful for chemical imaging. Indeed, it is not trivial to separate the chemical information of the sample from the physical information describing the phase relationship of the scattered photons. However, Bruker has addressed this (and more) with HYPERION II. It is finally possible to collect beautiful, coherence-artefact free chemical IR images in any measurement mode.

Finally, almost all the lights have “color temperature” controls (besides the Auxiwa Clip-On and ShiftCam SnapGrip Creator Kit — and the Rotolight Ultimate Vlogging Kit utilizes plastic discs instead of temperatures lights, as described above). The USB lights we tested have three different controls, which allow them to provide warmer or cooler light depending on the vibe you're going for. Both the Westcott Kit and the Neewer Kit allow you to dial the white balance between 3200K and 5600K, and the Neewer Kit also includes red filters you can snap onto the light.

We determined value by comparing the price of a ring light to its performance (i.e., its overall score). The UBeesize 10" Table Top and Xinbaohong Clip-On are quality options if you want to save money while still getting a decently performing product. You forfeit many of the fancy features that the more expensive models offer. However, you still receive a decent light at a fraction of the price with either one.

Quantum Cascadelaser price

To measure and compare sheer brightness between these often very similar devices, we used the LT300 Light Meter by EXTECH. We were sure to measure each ring light from the same distance of 36 inches away and with no ambient light present. We even tested each light multiple times to confirm all readings. The lights in our test suite emit a large range of lumens.

Is QCL better than FT-IR? It fully depends on the specific experiment since both techniques have unique benefits and limitations. While QCL has a limited spectral range but provides high imaging speeds, FT-IR offers the full MIR spectral range at limited acquisition speed.

Quantum cascadelaser PDF

FT-IR micro spectroscopy can be significantly augmented by QCL-based IR microscopy, because of the complementary nature of both techniques. Although modern QCLs cover the entire spectral fingerprint region, the full Mid-IR region is, however, not yet accessible. This becomes particularly apparent since a broad spectral range is an innate strength of FT-IR and extending the range of QCL systems comes at a significant cost.

Especially in microscopy, this often requires liquid nitrogen for cooling. Additionally, the detectors need to be very fast to be able to record interferograms in a spectrometer. A QCL, on the other hand, will emit all its photons on approximately the same wavelength. That means that the spectral power density of a QCL is typically orders of magnitudes higher than that of a thermal source.

Can I combine FT-IR and QCL? Bruker will soon offer a seamless integration of both techniques in one intrument. This way you gain both benefits by avoiding any limitation.

The ring light you choose must stand up with a camera/phone attached. We set up each model, attached the largest camera or phone possible, and then jostled it vigorously to see whether it could stay up. We also assessed whether each could support a phone or DSLR and whether we felt confident that our electronics were actually going to stay where we put them.

Quantum cascadelaser spectroscopy

What is QCL IR imaging? For QCL IR imaging, a QCL microscope is designed as a widefield setup, where a microbolometer array is recording full images of a microscopic sample at video framerates. By using a array detector, very high data acquisition rates can be achieved.

Where are QCLs applied? Currently they are most used in QCL IR microscopes, spectrometers and in systems for trace gas detection.

In a QCL, the radiation is not generated by the classical recombination of an electron from the conduction band with a hole of the valence band. If an appropriate bias voltage is applied to the QCL, the electrons in the conduction band of the semiconductor will start to "cascade" through the stack of active regions and injectors. Each electron will perform a laser transition in an active region, creating a mid-infrared photon.

Auxiwa Clip-On — This light isn't bright enough to do much; you can see how it doesn't fill in the right side of the face.

The Xinbaohong Clip-On is a lightweight and compact clip-on ring light for smartphones. It offers multiple temperature settings, continuous dimmer capability, and the most basic setup imaginable — all at a very affordable price. It clips directly to the phone, like a chip clip. A single power button turns the light on, and successive presses cycle through the temperature modes. Super easy. It can easily fit into a backpack, purse, or jacket pocket. This is a great option for budget-conscious social media posters and selfie-takers alike.

While the price is right, this ring light has some downsides. When using it in a portrait orientation, the clip mount blocks the rear-facing camera of many phones, which is an issue when taking a non-selfie photo. To mitigate this problem, you either have to slide it to the corner or a different side of the phone. Another consideration is the light itself is not particularly bright, so if you photograph anything more than an arm's length away, this light won't make a noticeable difference. Also, for everything we love about this mini light, it feels lower quality than other premium portable options. Still, for its simplicity and ease of use at a steal of a price, the Xinbaohong is a nice portable light for selfies. If you have a little wiggle room in your budget, check out the well-designed UBeesize 10" with Tripod, which includes a solid tripod and is quite bright.

The Westcott 18" might be too big, depending on your lighting needs. Setup requires a tripod, so adequate floor space is necessary. Also, it lacks a remote and does not offer Bluetooth availability to control the light settings remotely. Compared to a standard ring light, this model is also a bit more expensive, but we found the high-quality construction and utility well worth the cost and great for various applications. If a compact, remote-triggered ring light is what you're after, you can enjoy the UBeesize 10" Table Top at a fraction of the price.

In short, it is a tunable Mid-IR laser - but let's go into more detail. A quantum cascade laser is a heterogeneous diode laser and as with any diode laser, radiation is generated by applying voltage to it. In contrast to a classical homogeneous diode laser that produces only a single wavelength, a QCL can emit light in a range of wavelengths in the mid and far infrared. To do this, the QCL is placed in a so-called external cavity, in which the emitted wavelength can be selected by tilting a grating. This process is called "tuning". In a QCL, distinct semiconductor layers are stacked on top of each other to form the diode. The total length of the laser diode reaches several millimeters, although each individual layer is only a few nanometers thick. Depending on the thickness of the individual layers, a stack of layers can either form an “active region” or a doped electron injector. Typically, a QCL consists of a series of pairs of active regions and injectors.

We focused most of our testing on the amount and quality of light produced by each product. We deemed brightness the most important factor of light quality. However, a few other characteristics also come into play, like dimmability and the variety of tones each kit offers.

The ShiftCam SnapGrip Creator Kit is simple once you have the hang of it, but there are three layers between the MagSafe adapter sticker, the light itself, and the tripod/selfie stick, so it takes a minute to figure out how it all needs to go. We like the similar designs of the Sensyne 10" Ring Light with 50" Extendable Tripod and the Razer Ring Light 12". They have legs that deploy in three stages for easy adjustment. The Sensyne, however, has a max height of 50 inches, so it's not quite tall enough for most adults to be used if you are standing up.

This light has just a few drawbacks worth noting. First, it is not especially bright. It does the job for selfies or anything within close range but much more than an arm's length away, and its effectiveness fades fast. Second, it's heavy, which you might notice if you plan on taking a bunch of selfies with the included stick. When attached to the stick, the weight of the light combined with a phone sometimes forces the pivoting ball joint to slump over at an angle. However, for convenience and quality in a tiny package, this light is our go-to when on the go. If you can't swing the cost, check out our favorite portable budget model, the Xinbaohong Clip-On. It's lightweight, affordable, and fits in your jacket pocket, so you can take a selfie whenever the moment strikes.

What is a quantum cascade laser? A quantum cascade laser (QCL) is a heterogeneous diode laser that can emit radiation in a range of wavelengths, specifically in the mid infrared (MIR) region of the electromagnetic spectrum.

In certain scenarios, such as real-time infrared imaging, this makes the QCL-based instrument much more efficient than its FT-IR-based counterpart.

What can QCLs do? QCLs can be used as a source of infrared radiation in IR spectroscopy. Such QCL IR instruments do not require an interferometer but offer a limited spectral range.

Basically, QCL spectroscopy utilizes the fact that quantum objects (e.g. electrons) must adopt discrete states in a potential well. These potential wells and therefore the energy of quantum objects in it can be defined by the design of the individual layers of the heterogenous semiconductor structure of the QCL. Thus, by specifically designing of each active region of a QCL, we can determine which wavelength will be emitted during the transition of the electron.

This review is the collective work of several veteran GearLab testers. Senior Review Editor Richard Forbes has been shooting photos with a wide range of cameras (from phone and film to pro-DSLRs) for nearly two decades and has been a working photographer for seven years. He firmly believes that photography is painting with light, so he spends way too much time thinking about how to get the right light in the right place. He loves to use ring lights on shoots and for his own selfie game. Richard is joined by Hayley Thomas, a lover of photography since she was a child, growing up with her photographer mother. She has a keen eye for composition, and her Canon Mark IV 5D is never far from her side. Ben Applebaum-Bauch has been with the GearLab team for almost six years. In that span, he has tested hundreds of home goods and electronics products, taking dozens of product photos each time. Often relying on the assistance of a ring light, he knows what to look for in these models that will bring the best user experience and lighting to the shoot.

As with many things, if a product is unnecessarily complicated, you may not use it. Within this metric, there was a wide range of well-designed (and not so well-designed) products, and to sort out which products made it the easiest for us, we set them up and broke them down repeatedly.

Quantum cascade laserswikipedia

What is a laser? A laser is a device that emits coherent radiation created by stimulated emission. (LASER: light amplification through stimulated emission of radiation)

When it comes to sheer brightness, the Westcott 18" Kit edges out the Lume Cube 18". The former emits a whopping 2435 lumens, and the latter an exceptional 2267 lumens. The Neewer 18" Kit takes third at 2065 lumens, which is still extremely impressive compared to the rest of the products in our test suite. These models are wall-powered lights (though the Westcott also comes with batteries). Part of the reason for the out-of-this-world brightness on these three is their size; they both have roughly 25 times the lighting surface area as the tiny Auxiwa Clip On, which gives them quite the advantage. The Westcott, Neewer, and Lume offer continuous dimming, meaning the dimming is completely customizable. The Westcott 18" also offers a sliding tone scale, which is a rather unique feature. If you are searching for the absolute brightest, you should go with one of these larger lights. The Razer Ring Light 12" is smaller and less powerful. Still, at 789 lumens, it holds its own, especially compared to its closest competitors, the Ubeesize 10" with Tripod and Sensyne 10" Ring Light, which emit just a couple hundred lumens.

Seeking to improve the light quality of your photos or videos? We researched over 60 top contenders and purchased the 14 best ring lights for some quality hands-on time. We put each one through the wringer to ensure a well-rounded testing process. We shot a ton of selfies and portraits, timed the setup and breakdown of each model, assessed stability and durability, and came away feeling confident that we'd tested these lights to the best of our abilities. Read on to learn more about our favorites and our testing methods. Your home photos will level up in no time!

If a QCL is meant to be used for spectroscopy in a broad spectral range, the design of the active regions must be adjusted accordingly. For example, the so called “bound to continuum” designs will create a quasi-continuous spectrum of photons in a broad spectral range. By placing the QCL in an external cavity, the emission wavelength of the laser can be set to any wavelength that’s within the spectrum of the active region, creating a tunable mid infrared source.

Interbandcascadelaser

Like most bargain buys, there are some downsides to consider. For instance, we wish the phone mount was more compatible with larger phone cases (e.g., Otterbox). Also, this smaller ring light costs less than others in our lineup and, as a result, lacks the brightness that larger, more expensive models do. That said, neither issue is a dealbreaker compared to how much we like this light. The UBeesize 10" Table Top is a small, simple, and portable option, all at an unbeatable price. If you require a model compatible with larger phones, the Westcott 18" Bi-Color LED is a more viable option. It features a remarkably bright light and works with large phones and cameras alike.

We also looked at additional features in this category. We gave products higher ratings if they included things like a remote trigger (for use with a phone), like the UBeesize 10" with Tripod, or a tripod that can turn into a selfie stick, such as the Aixpi 10" with Tripod, ShiftCam SnapGrip Creator Kit, and Rotolight Ultimate Vlogging Kit. The UBeesize 10" Tabletop tripod can technically be used this way, but it is a little impractical given the size of the light and its wired setup. Again, the ShiftCam SnapGrip Creator Kit impressed us here with the added capability of the SnapGrip portion to wirelessly charge the phone it is attached to while in use. One super basic but unique feature of the Sensyne 10" Ring Light is that the included tripod has a bubble level to ensure a superior level shot.

Regarding portable models, the Rotolight Ultimate Vlogging Kit is exceptionally bright for its size, boasting up to 1000 lumens, which is multiple times brighter than lights of equivalent size. However, in terms of overall quality, this model suffers because it's not dimmable. Instead, you must manually swap the plastic temperature disks over the light face to change the light quality.

To understand why QCL opens a new door to an exciting path of infrared spectroscopy, we must first take a closer look at the gold standard: FT-IR. Keep in mind, that quantum cascade lasers fundamentally differ from the conventional thermal sources which are used for FT-IR. A traditional, thermal source emits photons over a broad spectral range. Therefore, the number of photons per wavelength is quite small and consequently, the detectors for FT-IR spectroscopy must be highly sensitive.

Our timed setup test revealed this most clearly, as the large Neewer and Westcott lights took the longest to set up (at roughly one minute and 15 seconds each), while the Xinbaohong Clip-On and Auxiwa Clip-On took only five seconds to clip onto a phone (though the Xinbaohong also blocks the rear-facing camera on an iPhone, so it's primarily useful for selfies). In the middle of the pack, some lights were unnecessarily fiddly: in particular, the Aixpi 10" with Tripod took 50 seconds to set up just because the parts didn't fit together well.

On the other hand, the main drawback of an FT-IR microscope remains the limited acquisition speed, which in turn is not a problem for a QCL-based widefield setup. By combining the two techniques, disadvantages can be avoided, and their advantages combined to increase the efficiency of both. This is precisely why scientists need to carefully compare FT-IR and QCL in real-world scenarios. This is the only way to sustainably transfer and improve established IR applications. Likewise, it is essential that new QCL methods are verified by FT-IR to make them more reliable and robust.

The ShiftCam SnapGrip Creator Kit and Rotolight Ultimate Vlogging Kit are some of the most sturdy portable models. This is partly due to their smaller size — fewer hinges and joints to break on tripods, for example. However, they are also both well-constructed. The ShiftCam is rubber-coated and comes with a zippered protective semi-rigid case for travel, while the Rotolight has a durable metal T-bar mount. The UBeesize and Westcott lights are the heartiest of the bigs, and we are confident the UBeesize 10" Tabletop, UBeesize 10" Tripod, Razer Ring Light 12", Westcott 18" Kit, and Neewer 18" Kit will all last a long time. On the other end of the spectrum, the Xinbaohong Clip-On, Auxiwa Clip On, Mactrem 6" LED, and Aixpi 10" with Tripod are all underwhelming and strike us as liable to break if the light were to fall on the floor.

What is a QCL IR microscope? A QCL IR microscope can be used to create chemical images of microscopic samples. It acquires spectral information in every pixel of a chemical image, revealing the distribution of the chemical components of the sample.

Ring lights are an essential tool for anyone who films or photographs faces. They provide a kind and diffused light that removes shadows and helps subjects stand out from their backgrounds. Even if you're just doing a ton of Zoom calls, ring lights will help you look your best. Our expert testers subjected each product to a series of rigorous tests designed to reveal any strengths or weaknesses and then sorted the results into four weighted categories.

Because the electrons remain in the conduction band after each laser transition, each electron will generate multiple photons, one for each active region of the QCL. Over the recent years, the average output power of tunable QCLs increased and the accessible spectral range broadened significantly. The performance improvements at their core are based on improved quantum mechanical calculations describing the energy states of electrons in active regions and injectors.

Quantum cascadelaser applications

Almost all of the lights have varying brightness levels, from the stepless dimming of the Westcott 18" Kit and Neewer 18" Kit to the 9-11 brightness settings of the USB lights to the four and three levels, respectively, of the ShiftCam SnapGrip Creator Kit and Auxiwa Clip-On. However, we found ourselves almost always using the lights to their full capacity, so the dim settings didn't matter much.

Neewer 18" — And this is it, exactly what these lights are supposed to do. You can see the catchlights in the eyes, and the face stands out from the background. There's a world of difference between this and the “no light” selfie.

On the other hand, the Westcott 18" Ring Light is one of the most expensive ring lights we tested, so we would expect it to perform extremely well across all of our metrics, and it does. It delivers value with excellent light quality and sheer brightness. It is easy to use, stable, and durable, making it a versatile and long-lasting product. That said, this option is only worth the money if you are looking for a more advanced model. If you want something of high caliber but don't need or want to pay for extra features, the Neewer 18" Kit is another solid value pick.

The widefield setup is one of various designs of QCL microscopes. Here, a larger sample area is illuminated at once and the transmitted or reflected radiation is then detected by a microbolometer array. And since QCL sources offer a much higher spectral power density, we can use these detectors to acquire infrared images at video framerates.

Aixpi 10" LED Tabletop — This one fills the face pretty well, but the right side is still lost. The photo also has a green cast, but you can start to see the ring light catchlights.

The Westcott 18" Bi-Color LED has you covered, from selfies to outdoor shoots. With 2435 lumens and a 3200K-5600K temperature range, you'll be set for photography, video calls, blogging, and much more. This ring light has a stepless dimmer and digital readout, allowing you to fine-tune brightness and temperature with the turn of a dial. The digital readout lets you quickly change settings based on external light conditions. The light includes two NP-F750 lithium-ion rechargeable batteries and a battery charging port. These batteries keep the light going on full power for 70 minutes, and there is also a wall-powered option for extended use. This ring light comes with a sturdy tripod and mounting accessories capable of holding a DSLR camera or smartphone. In addition, it has a USB port capable of charging phones and other electronics to avoid low battery interruptions. This light and its accessories fit nicely into a well-made storage bag with separate light, tripod, and battery compartments.

To understand durability, we spent time setting up and breaking down each light repeatedly to identify any weak spots they might have. We supplemented our assessments by reading user reviews to see if there were any common problems. We were sure to put them through all the paces that a busy videographer or photographer might.

There were a lot of different DSLR holders and phone holders, though some were better than others. We were impressed by the UBeesize phone holder on both models we tested: the UBeesize 10" Tripod and the UBeesize 10" Tabletop. The holder has a solid feel and grips phones well. The Lume Cube 18" has a stable tripod, but we struggled to get iPhone Plus models into the holder. The Razer Ring Light 12" and Sensyne 10" Ring Light with 50" Extendable Tripod have level tripods with a wide base. However, they are both relatively lightweight, so they can get knocked over easily if you bump into them. The Rotolight Ultimate Vlogging Kit has a stable mini tripod. But, we found that the weight of the actual light can cause the whole apparatus to tip to one side, especially if no phone is attached to anchor the other side. The Aixpi 10" LED Tabletop is so short that it has a low center of gravity, making it relatively stable. The Mactrem 6" LED strangely has two different tripods, both poorly balanced.

Just like a conventional FT-IR microscope, a QCL IR microscope allows for chemical imaging of microscopic samples by acquiring spatially resolved spectral information. But instead of spending the time to capture a full IR spectrum at each measurement point, it enables you to focus on a specific spectral range and thereby increases the imaging speed by an order of magnitude. In short, you get a QCL IR imaging microscope, when you replace the standard broad band thermal source and the spectrometer used for FT-IR with a quantum cascade laser and switch the N2-cooled FPA-detectors of an imaging FT-IR microscope with a room temperature microbolometer array.

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Quantum cascadelaser working principle

Unfortunately, the phone holder on this model has the same issues as the others — it doesn't grip phones with a large case well. We also wish the light was slightly brighter, though it's the brightest of the 10" sized lights we tested. This is a great mid-size option at a very accessible price point. If you need a brighter model, the Razer Ring Light 12" is a solid option that's cheaper than the priciest premium products we tested.

To show more about how they look (and how the different lights compare), we took a bunch of selfies with different exposures (in camera) to make the lighting similar. This approach shows how the different light sizes change the face and the photo. We did not edit these photos at all.

The ShiftCam SnapGrip Creator Kit is a top choice for content creators who need a reliable light on the go. This portable device turns a phone into a more traditional-looking camera by adding a shutter button, light, and detachable mini tripod to any smartphone. The tripod legs also easily collapse down into a selfie stick. This light uses MagSafe magnetic technology to quickly click in place on your phone. It even comes with an adapter sticker that turns any non-iPhone into a MagSafe magnet-compatible device. It also strikes us as high-quality and comes with a semi-rigid case to protect the light and battery.

We love the versatility of the UBeesize 10" with Tripod — it comes with some great features, and they're all well-designed. It has an excellent, fully functional tripod and a carry bag for the light. There's a separate carry bag for the tripod, and it also includes an easy-to-use remote trigger for your phone. This light sets up fast (we managed it in 18 seconds), and adjusting it is a dream. It also features the same phone holder as the UBeesize 10" Tabletop, which can easily twist to whatever angle you want.

Mactrem 6" — This one fills the face better; you can't see the side lighting as dramatically, but you still can't see the characteristic eye “catchlights.”

In addition, it would be disingenuous to ignore the obvious issue with a “brightness only” approach. This test has a huge range of sizes, from the enormous 18" Neewer model to the tiny Auxiwa Clip-On. Obviously, the largest lights should be the brightest, so we also measured the ring lights' exact sizes (which were roughly as advertised) and compared these values to brightness values.