Liquid lenses are a relatively new integrated vision technology that is quickly gaining traction. In a wide range of situations where an autofocus camera is required, they offer significant advantages over ordinary lenses. Their adaptability and versatility have also played a big role in their widespread popularity. The purpose of this blog is to explain what liquid lens technology is and how it functions.
What is a liquid lens?
A liquid lens is a camera technology that substitutes a static optical glass lens. It uses optical-grade liquid in the center of a cell structure and functions similarly to an eye lens. A liquid lens permits the lens to change the form by means of adjusting the liquid inside it, which improves focusing speed and focal length.
How does a liquid lens camera work?
Consider a single droplet of water on a leaf, as seen in photography magazines. In the same way that this bead refracts natural light, the fluid in a liquid lens focuses light onto an image sensor. Liquid lenses rarely require mechanical components. Instead, they're filled with a transparent fluid capsule. By applying pressure on a piece of this pod, you can change its shape. Squashing or stretching the optical-grade fluid changes the trajectory of light moving through it as well as the focal length.
In a liquid lens camera, the lens exerts pressure on the capsule via a variety of means. 'Electrowetting,' for example, is a method that involves combining water with a separate layer of non-conductive oil in the lens. Putting voltage over the border in a fraction of a second can also modify the curvature and refractive effect.
Differences between the liquid lens and traditional lens
The main difference is that typical camera systems use glass optical lenses with a fixed curvature radius. Liquid lenses, on the other hand, are microscopic cells that contain an optical-grade liquid (a mixture of water and oil) that may change shape, resulting in changeable curvature and focal lengths.
Another distinction is that liquid lenses determine depth-of-field and focus on objects much faster than optical lenses. As a result, they can maintain focus even when the subject moves, whereas optical lenses struggle to regain focus.
How does liquid lens autofocus differ from VCM autofocus?
Autofocus in cameras is achieved using predominantly two types of lenses – a liquid lens and a VCM (Voice Coil Motor) autofocus lens. There are no mechanical pieces inside liquid lenses, making them unique. At the same time, a VCM autofocus camera relies on the mechanical movement of the lens to change focus. This leads to challenges like wear and tear (which implies reduced lifetime), increased heat dissipation, more power consumption, increased time to focus, etc. A liquid lens wins the game when it comes to all these parameters. For instance, e-con Systems’ 16MP autofocus camera See3CAM_160 – based on Sony IMX298 – comes with a liquid lens that delivers superior autofocus performance. e-con Systems also offers a 13MP autofocus camera based on the AR1335 sensor from onsemi.
Now let us look at a couple of disadvantages of liquid lenses in comparison with VCM autofocus lenses. Liquid lens is far costlier compared to VCM lenses. Also, the supply chain of VCM autofocus lenses is much wider, and hence offers better availability and supplier variety.
Interested in knowing more about autofocusing in liquid lenses and VCM? Please read our blog Liquid lens Autofocus vs. Voice Coil Motor (VCM) Autofocus.
Advantages & disadvantages of liquid lens
In the previous section, we looked at the differences between a liquid lens and a VCM autofocus lens. In this section, let us have a comprehensive look at the advantages and disadvantages of liquid lenses.
Liquid lenses provide several benefits over regular optical lenses, such as:
- It’s fairly compact when compared to traditional lenses used in embedded camera solutions.
- It’s also faster, has more focal lengths, and uses a lot less power than a motorized camera.
- A huge camera module with several lenses isn’t required – one liquid lens can handle all the focal lengths.
- It provides good image stabilization.
However, liquid lens technology has a few disadvantages, as well, namely:
- Experts opine that light scattering may cause issues.
- Preventing fluids from flowing in tight areas can prove to be challenging.
- Liquid lenses tend to be costlier than other lenses even in volumes of several tens of thousands.
