The IEEE website places cookies on your device in order to provide you with the best user experience. By using our website, you agree to the placement of these cookies. To learn more, please read our privacy policy.

Camera phones are one of the best-selling products among all consumer electronics products, and sales are expected to reach 170 million units this year. These gadgets have become ubiquitous, and almost no one would find it strange to see tourists squinting with one eye while pointing their phones at Buddhist temples, Greek statues or skyscrapers in New York City. It is easy to understand why analysts expect the sales of camera phones this year to exceed the combined sales of traditional digital cameras and traditional film cameras.

However, anyone who has seen them can attest that the images obtained from camera phones still have many shortcomings. Part of the problem lies in their CMOS imaging chips. Their sensor arrays are usually only about 300 kilopixels-a quarter or less of the number of low-end digital cameras. Of course, the fundamentals of the semiconductor industry ensure that 1-megapixel camera phones will soon become the norm. However, when they appeared, the only thing we could see more clearly was another weakness of these cameras: their tiny fixed-focus lenses had poor focusing and resolution.

We have a solution. It is modeled on the human eye and has extraordinary optical capabilities. We call it FluidFocus lens. Just like the lens of the eye, the lens we made at the Philips Research Laboratory in Eindhoven, the Netherlands, changes the focus by changing its shape instead of changing the relative position of multiple lenses like high-quality camera lenses. Our tests on the FluidFocus lens prototype show that it can be almost as small as a fixed focus lens. Fixed focus lenses use small apertures and short focal lengths to keep most objects in focus, but at the expense of light-gathering ability and therefore image quality.

At the same time, our prototype lens provides sharpness comparable to that of a zoom lens. In fact, the optical quality of a liquid lens combined with a megapixel imaging chip will soon make the quality of mobile phone snapshots comparable to images from traditional (larger) digital cameras.

The superior performance of the FluidFocus lens not only makes it an ideal choice for camera phones, but also in products where the design constraints require a compact but powerful optical system. Pocket-sized traditional digital cameras, PDA cameras, webcams, hidden security cameras, DVD burners, and endoscopes are just a few examples. Through extensive bioengineering, it is even conceivable that these lenses will be a key component of implantable artificial eyes in the future-a long-standing dream of ophthalmologists and science fiction writers. The superhuman zoom vision, which was first popularized by the protagonist of the American TV series "The Six Million Dollar Man" in the 1970s, is still far away, but now, at least, we know how to achieve it.

Traditional autofocus systems are not practical in today's camera phones and other portable devices because they use motors and gears to move the lens position. These components are difficult to miniaturize and are prone to wear. But our liquid lens has no moving parts or mechanical drive, which makes it more efficient and may have a longer lifespan. For example, these features are a big advantage of security cameras, they are constantly refocusing.

The human eye focuses on objects at different distances by contracting and expanding the muscles attached to the lens. The muscles change the shape of the lens and change its focal length.

On the other hand, our FluidFocus lens uses electrostatic force to change the shape of the brackish water droplets in a glass cylinder with a diameter of 3 mm and a length of 2.2 mm. One end of the cylinder points to the image plane; the other is for the object being imaged [see diagram, deformer].

The FluidFocus lens consists of a certain volume of water [blue] covered by a certain volume of oil [tan] in a glass cylinder [light blue]. The inner surface of the glass is a cylindrical electrode layer, an insulator, and the innermost waterproof material.

When there is no voltage on the electrodes, the water surface is convex [top]. And because the refractive index of oil is greater than that of water, parallel rays of light spread through the meniscus—the interface between water and oil.

The voltage on the electrode attracts water molecules to the surface of the cylinder, making it less repellent, and the water surface becomes concave [below]. Here, parallel rays of light passing through the meniscus converge at a focal point.

The cylinder containing the water droplets is filled with oil. The inner wall of the cylinder is surrounded by a waterproof Teflon coating, and behind the coating is an electrode. Basically, water and oil make up the lens, and the shape of the interface between the two—the meniscus—determines its focal length. Changing the voltage on the electrode changes the shape of the interface and changes the focal length of the lens.

The lens utilizes the surface tension properties of the fluid. The surface of the water column in the clean glass cylinder forms a bowl-shaped meniscus. Since the molecules in the glass attract water molecules, the liquid surface bends upwards near the clean cylinder wall. If the glass is greasy, the water surface near the wall bends down because the grease repels the water.

At the center of the meniscus, the water surface is almost flat due to gravity. Without gravity, the water surface would be spherical-this is the ideal shape of a focusing lens. In our lens, we eliminate the effects of gravity by keeping the droplets small and covering them with oil that does not mix with water. To completely eliminate the influence of gravity, oil must have the same density as water, because only in this way can gravity attract oil and water with equal force. In our lenses, we use a mixture of special silicone oils (phenylmethylsiloxane) with the same density. The result is that the shape of the water-oil interface will remain the same in any direction of the cylinder, but it can be changed by the voltage on the surrounding electrodes.

The optical power of the lens formed on the surface between oil and water depends on two things: the curvature of the meniscus and the difference between the refractive indices of oil and water. The refractive index-the ratio of the speed of light in a vacuum to its speed in a medium-characterizes the amount of bending of light as it passes from one medium to another. The curvature of the meniscus depends on the diameter of the cylinder and the strength of the cylinder wall to repel or attract water. This attractive or repulsive force varies with the voltage on the electrode.

In the next year or two, our FluidFocus lens may increase the resolution of pictures from mobile phones and PDA cameras

In our lens, the coating on the inner wall of the cylinder is so repellent that water does not even touch it: there is a very thin layer of oil between the coating and the water. Therefore, the water only touches the cylinder at one end of the plane, and the cylinder has no waterproof coating. In the absence of voltage on the electrode, the meniscus is hemispherical, with the center protruding outward beyond the ring where the water is closest to the cylinder. However, the voltage on the electrodes attracts water and creates a concave meniscus, forcing the edges beyond the center.

If liquid-filled lenses are a good idea, why were they not perfected long ago? There are three main reasons: the difficulty of counteracting the effects of gravity, the difficulty of accommodating the fluid so that its shape can be precisely controlled, and the difficulty of subsequently deforming the fluid in a controlled manner.

In the 17th century, British scientist Stephen Gray used water droplets to build microscopes, creating droplet lenses with a very small diameter—about 0.3 millimeters—so that their curvature was not strongly affected by gravity. Gray found that the images created by these lenses were very good, thanks to the smooth surface of the water droplets. He put the water droplets into the holes drilled in the plate to prevent the water droplets from moving around. Different apertures result in different droplet curvatures and different magnification factors.

In 1940, Robert Graham, who worked at Ohio State University in Columbus, tried to create a human-like lens by changing the amount of liquid between two flexible membranes. He did not succeed. Liquid leaks from the film, and worse, the elastic tension in the film makes it impossible to control the shape of the lens in a sufficiently precise manner to produce an undistorted image. In addition, the influence of gravity makes the shape of the lens depend on its orientation. (For the human eye, these problems are not serious because the lens is surrounded by liquid. Because the film around the lens is very thin, the distortion caused by elastic tension is small.)

Our method of designing a prototype lens started with Gray’s 17th century idea of ​​keeping the water drop in the center of the hole. It also draws on the discoveries of Aleksandr Froumkine and Christopher Gorman, two researchers in the 20th century.

In 1936, Froumkine began to use electric fields to change the shape of water droplets on metal surfaces. This phenomenon in which the electric field pulls the droplet toward the plate is called electrowetting: when the droplet is attracted by the electric field, it wets or touches the surface better.

In 1995, Gorman of Harvard University in Cambridge, Massachusetts, and his colleagues used electrowetting to make the first variable focal length lens, replacing the metal plate with a transparent conductive plate. They believe that these lenses can be used in adaptive optics for astronomical telescopes, which is a technique that dynamically changes the shape of mirrors to compensate for atmospheric effects [see "Removing flicker from starlight", IEEE Spectrum, December 2003]. An inherent problem with such lenses is that they are difficult to stabilize because they are not centered on the optical axis-the line that passes through the center of the aperture.

In 2000, Bruno Berger and Jerome Pessex of the Saint-Martin-de-Helle-Joseph Fourier University in France improved Gorman’s design, covering the transparent electrode with an insulating film, and adding a device to center the droplet . Berge is currently seeking to commercialize his liquid lens method at Varioptic SA in Lyon, France, which was founded in 2002.

Our solution to the centering problem combines electrowetting with Gray’s old concept of centering the droplet in a cylindrical hole (in our case a glass cylinder) and placing the electrode that generates the electric field inside the cylinder. , Instead of placing the ground plate inside the cylinder.

An important advantage of our liquid lens is that it can be very small. In fact, as Gray showed us, being small is inherently beneficial because it minimizes the effect of gravity on liquids. In addition, miniaturization makes the liquid lens more powerful, because as the size of the lens shrinks, the electrostatic force between the liquid and the inner surface of the cylinder becomes stronger.

This characteristic makes small electrowetting lenses very fast. Our prototype can refocus in 10 milliseconds, much faster than the human eye can refocus in about 200 milliseconds. Scaling to the size of the human eye lens, the refocusing time will increase to 50 milliseconds, which is still four times that of the eye.

So how good are these lenses? The refractive power of a lens is expressed in diopter, which is a measure of the ability of the lens to bend light. The diopter value of the lens is proportional to the reciprocal of the lens's radius of curvature in meters. The closer the object is to the lens, the more the lens must bend the light to focus it. Therefore, when the object is far away, the lens needs less power to focus it than when the object is close. Our liquid lens changes its focal point by changing the radius of curvature of the water droplet and the voltage on the electrode to change its optical power.

The strength of glasses is also expressed in diopter. So, for example, 2 glasses will increase the diopter of the eye by 2 diopters, allowing the wearer to see things close by.

The optical power of our lens, with an inner cylinder diameter of 3 mm, can be varied within a range of 150 diopters. This is achieved by changing the meniscus between a hemispherical shape (whose radius is equal to half the diameter of the cylinder) and a concave shape (whose radius is approximately equal to the diameter of the cylinder). If it is the same size as a human lens, its diopter range is about 50 diopters-12 times the diopter of the human eye, which is about 4 times the diopter range.

The main optical components of the human eye are the cornea, iris, lens and retina. The cornea is a transparent dome that covers the front of the eye and serves as its outer window. Next is the iris, the colored part of the eye, which forms the iris of the system—the pupil, which opens or closes to allow more or less light to enter. Behind the iris is the deformable lens, which is the part of the eye similar to our liquid lens, which focuses light on the curved retina at the back of the eyeball.

In the human eye, the main power of the lens system comes from the cornea, with a refractive power of about 40. The typical deformable human eye lens is about 9 mm wide and 4 mm thick. The lens has an optical power between 20 and 24 diopters and can focus near or far objects.

In the human eye, the cornea provides the main optical power, and the lens provides the variable focal length. The muscle attached to the lens changes its curvature to focus on objects at different distances. The closer the object is, the rounder the lens must be in order to project the focused image onto the retina at the back of the eye.

The human lens is composed of several thin layers of transparent tissue. The refractive index of the different layers ranges from 1.406 in the center to about 1.386 in the outer layer. This gradient in refractive index makes the focal length independent of wavelength—that is, it bends light of all colors equally. This is an important attribute for creating clear images.

In order to demonstrate the advantages of our liquid lens, we made a digital camera 5.5 mm high and 4 mm wide [see chart, "All Focus"]. On the back of the camera is a CMOS imager with a 640 x 480 pixel sensor array. Directly in front of the CMOS imager is a plastic lens, which can clearly project the image onto the flat CMOS image sensor. The eye does not need such a lens because the image sensor (retina) in the eye is curved.

In front of this plastic lens is a liquid lens in a cylindrical glass housing with an outer diameter of 4 mm and an inner diameter of 3 mm. The oil surface of the liquid lens is close to the imager. The glass plate seals the liquid lens on one side close to the imager, and a truncated glass ball mounted on the flexible film seals it on the other side.

The truncated sphere allows the focal length of the camera to be independent of wavelength-just like the human eye. This property is important because it focuses all the wavelengths that make up the image at the same point, resulting in a clear image. The membrane allows the volume of liquid to expand or contract according to temperature. In front of the truncated glass sphere is another plastic lens, which provides the main power like the cornea of ​​the eye. On the front of this plastic lens is a fixed aperture.

By changing the voltage on the liquid lens electrode, we can focus on any object from 2 cm to infinity. For this, we changed the focal length from 2.85 mm to 3.55 mm [see photo, "From here to infinity"].

Unlike the human eye embedded in a temperature control system, our lens must work within a certain temperature range. For portable applications, the lens must work between -30°C and 60°C and at a temperature between -40°C and 85°C. Since such a wide range requires a special liquid, we added a large amount of salt or antifreeze to the water in our prototype camera lens to sufficiently reduce the freezing point without adversely affecting the image quality.

However, there is one characteristic that our lens may not be able to beat the human body, and that is the life cycle. No autofocus camera we know of can run every day, every day, 80 years or more. However, we have changed the focus of the liquid lens-from one end of its range to the other-more than a million times without any performance degradation.

We are now working on the FluidFocus zoom lens. Optical zoom requires at least two lenses-one to change the magnification and the other to refocus the image. In principle, changing the magnification by moving the lens will make the image out of focus. Conventional cameras keep the image in focus through a rod system that connects separate lenses.

We are currently designing a zoom lens system that uses two liquid lenses in series. This lens will work by changing the shape and optical power of the two lenses, rather than changing their position. Compared with the traditional zoom lens, the liquid lens has two advantages: no moving parts and very small size, and the potential cost is very low.

The liquid lens can even be used in high-quality optical recording systems like DVD burners. Because its resolution is controllable, it is not limited by lens defects, but only by diffraction, which limits all The resolution of the lens system.

The lens has other interesting possibilities. Replacing the electrodes surrounding the inner wall of the glass cylinder with multiple vertical electrodes and adjusting their voltages respectively can tilt the interface between the liquids, thereby enabling imaging in a direction at a certain angle to the lens axis. A lens that can be tilted and focused allows engineers to design cameras and binoculars that can accurately compensate for hand movements and other undesirable movements.

We expect that in the next year or two, our FluidFocus lenses will increase the resolution of photos taken with mobile phones and PDA cameras.

Because liquid lenses are based on materials that are at least theoretically biocompatible, and because refocusing lenses requires very little energy, we can envision (forgive this expression!) future applications to replace malfunctioning human spectacle lenses. With the zoom function, we may even far exceed it. Imagine being able to read a car license plate a kilometer away or a menu in a restaurant window without getting off the car.

Before that, we still have a lot of work to do. But to make this science fiction dream a reality, what we need most is a vision.

Benno Hendriks joined the Philips Research Laboratory in Eindhoven, the Netherlands, in 1990, working on electron optics. Six years later, he turned to optical recording and joined the FluidFocus project in 2002, specializing in the optics of liquid lenses. He received a doctorate degree. In 1989, he obtained his Ph.D. degree in quantum optics from Utrecht University in the Netherlands.

Stein Kuiper is the leader of the FluidFocus project, which was launched in 2000. Earlier in the same year, he received his doctorate. PhD in Physics, University of Twente, The Netherlands.

Bruno Berge and Jerocircme Peseux reported on their liquid lens work in The European Physical Journal E 3 (2000), p. 3. 159.

The technical details of the FluidFocus lens are published in S. Kuiper and BHW Hendriks, Applied Physics Letters 85 (2004), p. 1128.

http://www.umiacs.umd.edu/~ramani/cmsc828d/lecture3.pdf has a clear explanation of how the human eye and camera lens work.

Does more than 100 mobile robots indicate that everyday robots are inevitable?

Last week, Google, Alphabet or X or whatever company you want to call it announced that its Everyday Robots team has grown enough and made enough progress. Now it’s time to make it its own thing. Now you guessed it. You guessed it, "Everyday Robots." There is a problem with the design of a new website, and there are a lot of fluffy descriptions about the content of Everyday Robots. But fortunately, there are some new videos and enough details about the engineering and team approach, it’s worth spending a little time trekking through the chaos to see what Everyday Robots has done in the past few years and what plans they have done. For the recent.

The place near the arm does not seem to be suitable for placing an emergency stop, right?

Our headline may sound a bit acrimonious, but the headline of Alphabet’s own announcement blog post is "Every day robots leave the laboratory (slowly)." It is not so much a sarcasm, but rather an admission that the mobile robot is in a semi-structure. Effective operation in a chemical environment has been and will continue to be a huge challenge. We will go into details later, but the high-level news here is that Alphabet seems to have invested a lot of resources behind this effort, has a long time span, and its investment is beginning to pay off. Considering the random state of Google Robotics over the years (at least from the appearance), this is a nice surprise.

According to Astro Teller, who is in charge of Alphabet's moon landing program, the goal of Everyday Robots is to create "a universal learning robot", which I think sounds enough. To be fair, they deployed a lot of hardware, Hans Peter Brøndmo of Everyday Robots said:

This is a lot of robots, which is great, but I have to question the actual meaning of "autonomy" and the actual meaning of "a series of useful tasks". For us (or anyone?), there is really not enough public information to evaluate what Everyday Robots does with its 100 prototype fleets, how much robot support is needed, the constraints of their operation, and whether to call their work." "Useful" is appropriate.

If you don't want to browse Everyday Robots's weirdly over-designed website, we have extracted good things (mainly videos) and reposted them here, along with some comments below each.

0:01 — Is it just me, or does the gearing behind these actions sound a bit, eh, unhealthy?

0:25-I think the claim of winning the Nobel Prize by picking up the cup from the table is a bit exaggerated. Robots are very good at sensing and grasping cups on the table, because this is a very common task. Like, I understand, but I just think there are better examples to illustrate the current problems of humans and robots.

1:13 — It’s not necessarily useful to make an analogy between a computer and a smartphone and compare them to a robot, because certain physical realities (such as motors and operating requirements) prevent the kind of zoom that the narrator refers to.

1:35 — This is a red flag for me, because we have heard about "this is a platform" many times before, but it has never been successful. But in any case, people continue to try. It may be effective when limited to the research environment, but fundamentally, “platform” usually means “making it do (commercially?) useful things is someone else’s problem. I’m not sure if this has ever been A successful model of a robot.

2:10-Yes, okay. This robot sounds much more normal than the one at the beginning of the video; what's the matter?

2:30 — I am a big fan of Moravec's Paradox, and I hope that when people talk about robots with the public, it will be mentioned by more people.

0:18-I like the door example because you can easily imagine how many different ways it can be disastrous for most robots: different levers or knobs, different glass positions, variable The weight and resistance, then, of course, the threshold and other similar annoying things.

1:03-Yes. I can't emphasize enough, especially in this case, computers (and robots) are really bad at understanding things. Know things, yes. Know them, not so much.

1:40 — People really like to cast a shadow on Boston Dynamics, don't they? But this seems unfair to me, especially for companies that Google once owned. What Boston Dynamics is doing is very difficult, very impressive, come on, very exciting. You can admit that when you are dealing with different difficult and exciting problems yourself, others are dealing with difficult and exciting problems, and don’t feel a little annoyed by what you do, for example, not so flashy Or whatever.

0:26 — It doesn't make sense to say that the robot is low cost, without telling us how much it costs. Seriously: the "low cost" of a mobile manipulator like this is easy (and almost certainly is) at least tens of thousands of dollars.

1:10 — I like to include things that don’t work. Everyone should do this when presenting a new robotics project. Even if your budget is unlimited, no one can always do everything well, and we all know that others are as flawed as we are, and we will all feel better.

1:35 — When talking about robots trained using reinforcement learning techniques, I personally avoid using words such as "intelligence" because most people associate "intelligence" with the kind of basic world understanding that robots don't really have .

1:20 — As a research task, I think this is a useful project, but it is important to point out that this is a bad way of automatically sorting recyclables from trash. Since all the garbage and recyclables have been collected and (probably) taken to several centralized locations, in fact you only need to have your system there, where the robots can stand still and have some control over their environment And do better and work more efficiently.

1:15-Hope they will talk more about this later, but when considering this montage, it is important to ask in the real world what tasks do you actually want the mobile manipulator to perform, and which do you only want to perform Tasks are automated in some way because they are very different things.

0:19 — It may be a bit premature to talk about ethics at this point, but on the other hand, there is a reasonable argument that it is not too early to consider the ethical significance of robotics research. To be honest, the latter may be a better point of view, and I am happy that they are thinking about it in a serious and positive way.

1:28 — A robot like this will not take your job away. I promise.

2:18 — Robots like this are not the robots he is talking about here, but the point he puts forward is very good, because in the short to medium term, robots will become the most valuable role, and they can increase what humans can do by themselves. Things are not to completely replace human beings to increase human productivity.

3:16 — Again, the idea of ​​that platform...blarg. The whole "someone wrote these applications" thing, uh, who the hell is it? Why are they doing this? The difference between a smartphone (which has a lucrative application ecosystem) and a robot (which does not) is that there are no third-party applications at all, and the smartphone has enough useful core functions to justify its cost. It will take a long time for robots to reach that point, and if software applications are always someone else’s problem, they will never get there.

I am a little upset about this whole thing. A fleet of 100 mobile manipulators is amazing. It is also great to invest money and manpower to solve robotics problems. I'm just not sure whether the vision of the "daily robot" we are asked to buy must be realistic.

The impression I got from watching all these videos and browsing the website is that Everyday Robot wants us to believe that it is actually working hard to bring the universal mobile robot into the daily environment in the way people (outside of the Google campus) can benefit from it. Maybe the company is working towards that exact goal, but is it a practical goal? Does it make sense?

The ongoing basic research seems very solid; these are definitely difficult problems, and solving these problems will help promote the development of this field. (If these technologies and results are released or shared with the community in other ways, then these advancements may be particularly important.) If the reason for this work in a robotic platform is to help stimulate this research, that would be great, I There is no objection to this.

But I really hesitate to accept the vision of this universal home mobile robot to perform useful tasks autonomously. This approach may be of great help to anyone who actually watches the Everyday Robotics video. Perhaps this is the whole point of the vision of the moon landing-try hard to do something that will not be rewarded for a long time. Again, I have no problems with this. However, if this is the case, Everyday Robots should pay attention to how it puts its efforts (and even its success) in context and portrays it, why it works on a specific set of things, and how external observers should set it Our expectations. Time and time again, the company's commitment to useful and affordable robots is too high, but delivery is insufficient. I hope that Everyday Robots will not make the same mistake.

Here are ways to encourage daughters to pursue STEM careers

In my 2016 article "Fathers' Views on Daughters and Engineering", I shared my disappointment at the lack of role models and cultural information that made my two smart daughters — and many of their female friends — -To pursue an engineering career.

After the article was published, I received an email from Michelle Travis, she was writing a book about fathers and daughters. She wanted to know my thoughts on creating stronger channels for girls to pursue careers in science, technology, engineering, or mathematics (STEM), and what can be done to change the narrative of engineering to highlight their public service role.

Travis is a professor at the University of San Francisco Law School, where she co-directs her work law and judicial projects. She researches and writes articles on employment discrimination laws, gender stereotypes, and work/family integration. She is also a founding member of the Work and Family Researchers Network and serves on the board of non-profit organizations.

Her latest book, "Dads for Daughters" (Dads for Daughters) is a guide for male allies to support gender equality. (I am one of the fathers who appear in this book.) She wrote that my mother who won the prize has two jobs, which is a children's picture book celebrating working mothers.

Over the years, we have kept in touch, followed each other's work, and looked for other ways of cooperation.

In the past few months, I have been frustrated by the news that girls from certain countries are either not allowed to go to school or risk safety even if they are officially allowed to go to school. This is one reason why I feel I need to talk to Travis and learn from her what else can be done to change fathers and men's perceptions of women's abilities and women's success in almost all fields (including engineering).

Last month, I asked her a few questions about her book and what her father can do to better support women. In the next interview, she gave a sneak peek and listed some resources for engineering dads who wish to encourage their daughters to pursue STEM careers.

QA: As a lawyer, why did you decide to research and write articles about fathers and daughters? Is it personal?

MT: My interest in making my daughter's father an advocate for gender equality is both professional and personal. As a lawyer and law professor, I have been using legal tools for years to promote equality for women in the workplace-seeking stronger employment discrimination laws, equal pay for equal work, and family leave policies. Over time, I realized that the law has limits on what it can accomplish. I also realized that we are asking women to do too much heavy work to break down barriers and break the glass ceiling. Most importantly, I realized that to make progress, you need the commitment of a powerful male leader.

I started to ask myself how women can get more men to participate in gender equality work. At the same time, I noticed the powerful influence of my two daughters on my husband. He has always regarded the equality of women as an important goal, but it was not until he started to think about the world his daughter entered that he completely internalized his personal responsibility and influence. With a daughter, he is eager to take action. He wants to be an outspoken advocate for girls and women, not just bystanders.

"The father of an engineer has a unique position and can be an ally in expanding opportunities for girls and women."

Watching this transition prompted me to study the father-daughter relationship. I found that my husband's experience is not unique. Researchers found that having a daughter tends to increase men’s support for anti-discrimination laws, equal pay policies, and reproductive rights, which tends to reduce men’s support for traditional gender roles. This has a significant impact in the workplace. For example, fathers of daughters are more likely to support gender diversity than other male leaders. Compared with CEOs run by non-father men, CEOs who are daughter fathers tend to have a smaller gender pay gap in the company.

Of course, many men without daughters are allies of women, and not all fathers with daughters are advocates of gender equality. We have even heard some men-including famous politicians-citing their "daughter's father" in a dishonest way.

But fathers of most daughters are genuinely interested in promoting equal opportunities for girls and women. This makes the father-daughter relationship an excellent entry point for inviting men to form partnerships to build a fairer world.

QA: Why do people want to read your book?

MT: Today's fathers are training self-confident and capable daughters who believe that they can achieve anything. But the world is still unequal, the workplace is run by men, there is a gender pay gap, and deep-rooted gender stereotypes. My book celebrates the role father can play in creating a better world for the next generation of girls.

Inspired by their daughters, fathers are fully capable of becoming powerful allies for girls and women. But in the post #MeToo world, it may be difficult for men to step in and speak out. This is where the father of the daughter can help. It provides fathers with the data they need to advocate for gender equality. It also provides specific strategies to illustrate how they play a role in various fields, from sports fields to science laboratories, from conference rooms to ballot boxes.

In addition to serving as a guide, it also shares the stories of fathers who have joined the battle. All the men who emphasized praised their daughters for inspiring them to pay more attention to gender equality. These include a CEO who invests in female entrepreneurs to manage parts of his company's supply chain, and a lawyer who sets up a part-time position in his company-which allows women to maintain partnerships. Another head coach hired the first female assistant coach in the NBA. Another governor broke the partisan line and signed a bill to expand the rights of sexual assault victims. An engineer provides computer skills training to support girls who have become victims of sex trafficking in India. In addition, there is a teacher, a U.S. Army colonel, a plumber, a firefighter, and a construction contractor who have joined forces to fight for equality in the girls’ high school sports program.

All these fathers, and many others, are inspired by their daughters to support gender equality. Their stories can inspire other dads to participate. Fathers who are committed to seeing their daughters realize their dreams have the opportunity to improve the world their daughters will enter, and fathers born for their daughters will support them in this journey.

QA: What do you think is the difference between engineer fathers and other fathers, and why?

MT: Being an engineer's father has a unique advantage and can be an ally in expanding opportunities for girls and women. We all know that there is a huge gender imbalance in the STEM field. This leads to a large loss of talents. Daughters’ fathers can take small but influential steps in their homes, communities, and workplaces, welcoming more girls and women into engineering careers.

At home, the father can fill the home with books, toys and activities, so that the girl can imagine that she is the engineer of the future. The father of engineering has created some great resources for this. For example, Greg Helmstetter found that his daughter lacked an engineering role model, so he created the STEAMTeam 5 series of books, which shared the adventures of five girls using STEM skills to meet challenges. Inspired by his daughter, Anthony Onesto created the Ella the Engineer comic book series, which depicts a superhero girl who uses her engineering knowledge to solve problems and save the world.

Other excellent children's books include Rosie Revere by Andrea Beaty, engineer, and Tanya Lee Stone's "Who Says Women Can't Be Computer Programmers?" With Mike Adamick's father's Book of Awesome Science Experiments. Daughter’s dad can also follow Ken Denmead’s GeekDad blog, check the Go Science Girls website, and purchase one of Debbie Sterling’s GoldieBlox engineering suites for his daughter’s next birthday.

As an engineer, dads can have a broader impact in their communities by volunteering with girl technology organizations such as EngineerGirl, TechGirlz, Girls Who Code, Girl Develop It, or CoolTechGirls. These organizations are always looking for engineers to share their expertise and passion for STEM careers with talented young girls.

Engineer fathers can also become gender equality leaders in their workplaces. Hiring, mentoring, and funding women is a key step in expanding women’s representation in the engineering field. Dads can further support women by joining programs such as the Million Women Mentoring Program or cooperating with IEEE Women in Engineering or the Society of Women Engineers. The empathy that fathers gain from their daughters can also enable them to create a safer workplace culture by fighting hostile work environments and fighting gender prejudice.

QA: From the perspective of an adult daughter, what makes a father different from a husband or friend?

MT: In a recent survey, fathers listed strength and independence as the primary qualities they wish to instill in their daughters-this is different from the characteristics that men value their wives most. From the perspective of the daughter, this can make the father a particularly effective ally on their behalf.

When the father is involved in the daughter's life, this relationship can have a profound impact. Participating fathers will produce women who are more confident, self-esteem, and mentally healthy. Girls supported by their fathers have stronger cognitive abilities and are more likely to go to school and achieve greater financial success. The fathers involved also helped their daughters establish healthier adult relationships with other men.

For fathers, daughter relationships are a powerful way to build men’s empathy and raise men’s awareness of gender discrimination and gender inequality. For example, men generally understand the challenges of work/family integration better when they look at their adult daughters taking care of the needs of their careers and their mothers.