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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.

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We use the same two images to compute a phase contrast image, IDPC, from the difference of the left and right side images according to the DPC method11,12 Eq. (2)IDPC=IL−IRIL+IR,where IL denotes the intensity image captured with the left half of the brightfield LEDs on, and IR denotes the right half. Notice that the DPC image displays a shadowing effect along the horizontal direction because the patterns were split along the vertical direction. It is often useful to observe the phase contrast in both the horizontal and vertical directions, in which case we capture two more images with the top and bottom halves of the brightfield LEDs on. With the flexibility of the LED array patterning, any desired direction of asymmetry can be used to highlight features of interest.

The authors thank the UC Berkeley Yildiz lab, Dillin lab, and Prof. Shejian Liang for providing samples. This work is supported by the Development Impact Lab (USAID Cooperative Agreements AID-OAA-A-13-00002 and AID-OAA-A-12-00011), part of USAID’s Higher Education Solutions Network, and by the Office of Naval Research (grant N00014-14-1-0083).

A key application of our method will be for live unstained samples, demonstrated in Fig. 4 for Caenorhabditis elegans wild-type samples on nematode growth media petri dish substrate. The fast-moving and nearly transparent worms normally cannot be simultaneously tracked in different imaging modes. Using our LED array method, we achieve four-mode imaging at 50 Hz across all modes with 2160×2560  pixels in each image and a 16-bit dynamic range. A few sample frames of the resulting videos are shown in Fig. 4. Since these images were taken through the substrate, the phase contrast images highlight the small indentations left behind by the worms. The results are best appreciated by viewing Video 1.

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.

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.

For those looking to take their videos and photos to the next level, we've tested a ton of useful tools, many of which are smartphone-compatible. A smartphone gimbal can help smooth out your video shots, while an iPhone lens can change the focal length of your built-in camera, giving you more creative reign over your photos. With your camera phone in your pocket and cell phone accessories, you're sure to level up your media production.

Beyond the three contrast modes discussed in this paper, we note that the LED array microscope has recently been shown to be capable of enhanced resolution and three-dimensional (3-D) imaging, too, simply by choosing different illumination coding strategies. If one sequentially turns on each LED in the array, capturing an image for every illumination angle, the resulting dataset is four dimensional, akin to a light field.14 Thus, the data can be used to digitally refocus the image in postprocessing in order to synthesize 3-D intensity7 and phase contrast.9 Alternatively, if the object is thin, then the angular information can be used for computing large field-of-view, high-resolution gigapixel images via Fourier ptychography.8 While multiplexing achieves an order of magnitude reduction in the acquisition time and data requirements,10 these methods are still not suitable for real-time capture. Here, we focus on the three contrast modes that can be implemented in real time.

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.

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.

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.

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.

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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.

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.”

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.

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.

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.

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The ability to separate the phase from absorption information should be considered a significant advantage of DPC over phase contrast methods such as Zernike phase contrast, DIC, Hoffman modulation contrast,20 and Dodt contrast.16 The images produced look qualitatively similar to DIC, but contain no absorption effects. Since the illumination is partially coherent, the optical sectioning capabilities and lateral resolution of DPC are better than that of coherent techniques (interferometry) and the results are free from speckle noise. In addition, DPC does not rely on polarization optics, so the image will not suffer polarization artifacts for birefringent samples (e.g., muscle tissues and collagen fibers).12 DPC images can also be created without any modifications to the optical system after the sample (i.e., no specialized objectives or inserts). This simplicity of implementation has enabled its integration in real-time endoscopic imaging for in vivo studies.13,21

The experimental setup is an inverted Nikon TE300 microscope (Melville, New York) (shown in Fig. 1), where the illumination unit has been replaced with an LED array (32×32, 4-mm spacing) at 60 mm above the sample. The LED array subtends angles up to NA 0.73, ensuring that we can achieve darkfield illumination for most 40× and lower objectives. Note that the set of LEDs which make up the darkfield area will change with the objective NA, so the size of the brightfield circle should change based on the objective being used. Each LED is controlled individually in 8-bit grayscale by an Arduino (Italy) controller. An sCMOS camera (PCO.edge 5.5) is placed at the front port of the microscope for image collection and data are transferred to the computer via a CameraLink interface. The camera is synchronized with the LED array by the same controller.

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.

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Our experimental setup uses a programmable LED array in the source plane of a microscope to pattern illumination angles. By time-multiplexing different LED patterns, real-time multicontrast imaging is achieved with a single camera and no moving parts.

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.

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.

We have demonstrated the ability to capture multicontrast microscopy in real time for dynamic biological samples. Our results enable one to simultaneously visualize and compare images in brightfield, darkfield, and two directions of phase contrast. We demonstrated four modes of capture at 50 Hz with 2160×2560  pixels and a 16-bit dynamic range, with speed being limited only by the camera frame rate. For faster operation, one could use only three LED patterns (one direction of phase contrast) or trade off the pixel resolution or dynamic range for speed, up to a hardware limit of 500 Hz. Potential biological applications include live cell imaging studies, as well as small organisms such as C. elegans and Drosophila embryos. Unstained transparent samples are easily visualized in the phase contrast mode, while subresolution features (e.g., organelles and vesicles) show good contrast in darkfield. Due to the simplicity of the LED array microscope setup and the diverse range of imaging capabilities it enables, we expect that the LED array illuminator will find widespread use in a variety of applications.

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 second and third patterns are those of the left and right half circles, respectively, within the NA of the objective. Adding these two images together is equivalent to having taken an image with the full circle of LEDs, so it produces a brightfield image (with incoherence parameter σ=1): Eq. (1)IBF=IL+IR.

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.

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 wide range of lumens.

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To achieve brightfield, darkfield, and phase contrast modes, we capture time-interleaved images with three or five different LED patterns. The first pattern illuminates the darkfield LEDs of those which correspond to illumination angles larger than the maximum allowed by the imaging system.7 The radius of the circle defining the transition from brightfield to darkfield LEDs is set by the NA of the objective. When illuminating with darkfield LEDs, the only light that reaches the camera is that which has scattered from the sample, creating a darkfield image (see Fig. 2).

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.

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.

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.

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Experimental results using HeLa samples are shown in Fig. 3(a). Darkfield imaging provides contrast to the cell membranes and boundaries can be visualized easily, which is helpful for cell counting in densely cultured plates. For cell morphology studies, where the shape or volume of the cell is important, phase contrast will be the most suitable tool. For example, some epigenetics modulators like Trichostatin A can change the epigenetic state of chromosomes and cause the cell morphology to change from a round to an elongated shape. As another example, multicontrast imaging of model plant Arabidopsis can clearly trace nutrient transportation tubes in the root [see Fig. 3(b)]. The transport of dark material in these root structures can be studied easily by this microscopy system, since the vessel and transportation particles can be visualized by darkfield and brightfield, respectively. Note that the root hair structure at the white arrow is clearly observed in the darkfield, and the central vessel of root at the black arrow is clearly resolved in he brightfield. The phase contrast images in horizontal and vertical directions also selectively enhance the contrast along those dimensions, rendering better contrast in the radial vessel axils.

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.

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.

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We found the best overall light to be the Westcott 18" Bi-Color LED. We like that it has a digital readout for brightness and temperature and has the option to mount either a phone or DLSR. For something more portable, the Xinbaohong Clip-On is small enough to fit in your pocket and mounts directly on your phone when it's time to grab a 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.

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.

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 phones to 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.

Seeking to improve the light quality of your photos or videos? You're going to want a ring light. We purchased the 14 best setups and put each one through the wringer, shooting a ton of selfies and portraits, timing the setup and breakdown of each model, and assessing stability and durability.

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(a) Experimental results for HeLa cell samples imaged with a 20×, NA 0.4 objective in brightfield, darkfield, and Top-Bottom and Left-Right phase contrasts. (b) Experimental results for an Arabidopsis sample imaged with a 10×, NA 0.25 objective. All data were captured within 200 ms.

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.

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.

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 continuous 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.

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.

Experimental results for C. elegans wild-type unstained samples with real-time brightfield, darkfield, and phase contrast (in two directions). Shown here are a few sample time frames taken from a video (Video 1, MOV, 748 KB) [URL: http://dx.doi.org/10.1117/1.JBO.19.10.106002.1]. Images were acquired with a 10×, NA 0.25 objective at a speed of 50 Hz over 24 s.

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.

To implement the time multiplexing, the five (or three) patterns are displayed on the LED array in a continuous loop while collecting images for each pattern. Since the LED pattern transfer time (∼320  μs) is generally less than the exposure time required (e.g., 7 ms at 100 Hz), the maximum speed is limited by the camera frame rate. The captured images are processed in real time according to the simple operations in Eqs. (1) and (2) to obtain the multicontrast images (illustrated in Fig. 2). Results are regrouped to generate videos for each contrast mode.

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 grip.

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.

Our time-multiplexing scheme for multicontrast imaging in real time. (a) Five illumination patterns are displayed in a sequential loop on the LED array, while an image of the sample is captured for each. (b) The darkfield image is captured directly, while the brightfield and phase contrast images are calculated from sums and differences of the complementary halves of the brightfield LEDs, respectively. Here, we use both left-right and top-bottom phase contrast patterns; however, where only one direction of phase contrast is sufficient, only the first three patterns are necessary.

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.

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.

Intuitively, the phase contrast obtained by DPC comes from the asymmetry of the illumination patterns.15,16 A single asymmetric illumination pattern alone gives good phase contrast in the captured images, but using both patterns together allows us to relate the information to quantitative phase. Consider a purely real sample (no phase variations), which will produce a symmetric distribution in the pupil plane. The images from complementary illumination patterns (e.g., left and right) will thus be identical for all real (absorption) effects. Thus, the contrast obtained by subtracting two images with either side of the source on comes only from phase information of the sample. In fact, the DPC image can be shown to be directly proportional to the derivative of phase along the direction of asymmetry.11,12 In x-ray, a similar phase derivative result is obtained by grating interferometers,17 which can be considered a parallelized split-detector DPC measurement on the imaging (rather than illumination) side. Darkfield can also be extracted,18 and the derivative images can be integrated in order to recover the quantitative phase.12,19

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.

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.

Brightfield, darkfield, and phase contrast are the most common label-free contrast modes used in optical microscopy.1 Brightfield imaging is most suitable for observing samples with strong absorption. Darkfield imaging provides good contrast for subresolution features, since it only captures high-angle scattered light. Phase contrast is used for unstained and transparent biological samples, allowing visualization of shape and density variations. There are several commercial choices for phase contrast [e.g., Zernike phase contrast or differential interference contrast (DIC)2] and new methods which provide quantitative phase.3–6 Since each of brightfield, darkfield, and phase imaging provides complementary information about a sample, it is often desired to use multiple methods at once. However, in a traditional microscope, each contrast mode relies on a different optical hardware configuration, requiring inserts at the condenser aperture, polarization components, and/or specialized objectives. Here, we demonstrate a system which can achieve all three modes simultaneously by placing an LED array at the source plane and implementing simple postprocessing steps.

The LED array microscope is a new computational illumination platform in which a programmable source is combined with smart postprocessing algorithms to enable diverse imaging capabilities.7–10 An LED array is placed at the Fourier plane of the sample, replacing the original illumination unit of a commercial microscope (see Fig. 1). Each LED can be controlled individually to illuminate the sample from a unique angle, thus a set of LEDs on the array corresponds to a set of illumination angles. The brightfield imaging mode is achieved by illuminating with the central LEDs in the array, whereas darkfield uses LEDs corresponding to angles outside the imaging acceptance angle, set by the objective’s numerical aperture (NA).7 Recently, we have demonstrated that the phase contrast images can also be obtained in this system without any further hardware modifications.9 To do this, we employ asymmetric illumination differential phase contrast (DPC),11–13 in which one needs to only capture two images from complementary illumination angles. The resulting phase contrast image highlights shape and density variations along a single direction and is qualitatively similar to a DIC image. Three images taken under different illumination conditions are, therefore, sufficient for achieving all three brightfield, darkfield, and phase contrast modes. Five images can be used instead, if one wishes to capture the phase contrast along both orthogonal directions. We demonstrate here a hardware implementation that achieves such a multimodal contrast at high speed in a time-multiplexed fashion and show its use for imaging dynamic biological events.