[Tooling is explained in detail in our previous interview with Rick, which can be found by clicking this link: Rick Dickinson: The Enigma of Design (Part 1)
“It is always costly to tool up parts but for some things it is the only way you are ever going to get the features, functionality and, more importantly, the repeatability.
“So we did some trials at the Liverpool School of Tropical Medicine, looking at malaria. The trials were equivalent trials to see how it compared to £6000 Zeiss microscope, and we found that you could see just as much.”
The most important element in any optical system, be it a camera, telescope or microscope, is the lens assembly. As far as microscopes are concerned, this typically comprises an eyepiece, made up of an eye lens and field lens, a body tube leading to the objective lens, which is actually a container made up of a great number of individual lenses, and then a condenser lens, which, again, is composed of two or three lenses.
Before Rick and the team could really get to grips with the rest of the design it was essential that they found a manufacturer that would supply the accurate and high-quality lenses they needed to achieve 100 to 1000x magnification. The problem being that the lenses had to be unusually small for the product design to remain portable.
Rick: “If you take, say, three standard objective lenses that you find on any microscope anywhere in the world – they are all the same in principle because it is a global standard – and arrange them together to form a triangle, they take up a massive area, and by the time you put in some sort of mechanism that rotates them so you can dial in whichever one you want, and a focussing mechanism and lighting system, you have a product that’s about as big as a bench microscope! So we had to miniaturise them and the difficulty was finding a manufacturer to do that.
“A lot of people don’t understand what you are doing and are not interested. The volumes that we wanted were very small, relatively speaking, so people were simply not interested in the business. But eventually we found a company in China that already makes lenses, and we’ve since discovered that it is one of China’s largest optical manufacturers. They made us some prototype objective lenses and we went through various versions of those until we got what we wanted. The quality is just the same as a larger lens.
“Without the lenses you just don’t stand a hope really. They’ve got to be spot on: the quality of the glass, the coatings and the alignment. So the glass is all laser aligned and then set within a lens mount.
“We supplied the manufacturer with a specification for the working distance of the lens, which included, for example, the mechanical parameters and the sort of resolution we were looking for. It was then their problem to figure out how that was going to happen, so we didn’t get involved in that side of things. The manufacturer fits the glass into custom-designed lens holders and supplies us with very small objective lens assemblies that we simply screw in place, like you do on a normal microscope.”
Viewed from above, the three objective lenses can clearly be seen
Form Follows Function
The appearance of the Newton NM1 is very different to that of a traditional microscope, looking more like a miniature record player than a piece of scientific equipment. Its unconventional appearance is aesthetically pleasing, but the reason it looks that way is more to do with it having to be compact and portable than looking good.
“It is what you call an inverted microscope,” Rick explains. “With normal microscopes the lens is face down and the optical tube is just a straight path above. So you’ve got the lens at the bottom looking down on the specimen, and 160mm above that you have the eyepiece. That has been standard, really, since Leeuwenhoek designed his microscope. The standard design also has a table, or stage, beneath the optical tube, but because ours is an upside-down microscope and all the optics are underneath, our stage is totally uncluttered and has very little above it.”
The one part that does sit above the specimen table, looking a bit like the stylus arm of a record player, houses a bright light, powered by three AAA batteries. “At higher magnifications you need to pump in a lot of energy so that you can see the specimen,” continues Rick. “So you lift up that lighting arm, put your sample slide on the stage, just over the objective lens, and squirt light down through the slide and whatever is on it. That passes into the objective lens and that gets bounced around a few mirrors inside. The mirrors fold up the optical system, to keep it compact.”
Once inside the Newton NM1, the optical path deviates away from the object lens at a right angle, and then makes its way towards the eyepiece via a series of mirrors which bounce the light in a zigzag shape.
“It’s a three dimensional zigzag as well,” insists Rick. “We’ve got an application for a patent on that. The crucial bit is the third dimension. As soon as you drop under the objective lens you have to divert to the side otherwise you’d have a deep product. Then we fold it up a few times.”
Another innovative aspect of the design is the system used for controlling the microscope’s focus. Traditional microscopes use a rack and pinion focus mechanism, some even offering dual controls, where the first establishes a rough focus and the second enables fine adjustment. Rick’s team concluded that such mechanisms would be too expensive to manufacture and would detrimentally increase both the size and weight of the product. They decided to look for a different method of controlling focus and came up with something rather interesting.
“We ditched the rack and pinion type method because with it we would not have a portable or low cost product,” explains Rick. “We came up with a single focus control that rotates a cam, raising the objective lens carrier up and down to focus the lenses. It’s a continuous focus design, which means that you can’t go in the wrong direction because one full turn of the focus wheel in either direction delivers the full focus range, and there are no end stops. The old rack and pinion system has no way of telling you in which direction to turn the knob to find focus, so it’s a 50/50 chance that you’ll go the right way, and if you turn the wrong way you only find out when it reaches the end of the rack and you have to come all the way back past where you started. That is very tedious.
“Our design deals with the coarse and fine variations by the accelerating and decelerating effect of the cam profile, depending on where you are on the cam. This idea was a real breakthrough in miniaturisation, weight and cost for us and we are fighting to get a patent on it.”
This picture shows the zigzag light path within the microscope, from the eyepiece at the front to the objective lens behind
Taking the Knocks
One of the essential characteristics of a product that is for use in the field is that it is capable of withstanding a few knocks while it is transported around from place to place. Obviously, one way to make a product robust is to encase it in something extremely tough, like metal, but Rick was also very aware that the microscope couldn’t be too heavy or large. His solution was to try to reduce the mass of the object so that if it was dropped it would hit the ground with less force.
“A beetle is light, so it can fall a distance that is many times it own body length and still be fine when it hits the ground,” explains Rick, “but a human being can’t even fall over without hurting itself. That’s the principle I applied to the design, so it was all about using lightweight materials wherever possible, although I couldn’t go as far as I wanted because of certain limitations. For example, although we’d miniaturised the objective lenses, the manufacturers still had to make them in the traditional material that every objective lens holder is made in, which is brass. That’s because all their production processes are set up for brass. We would have liked to use aluminium or magnesium but unless you can give someone an order to go and make a million of them, no one is interested in investing in changing their methods of manufacture. These are the kinds of problems you have if you are doing something new!
“So we are stuck with brass lenses which are very heavy. The rest of the product is different. Internally the chassis parts are high-pressure die-cast aluminium. Pressure die-casting gives lots of features and good repeatability. Aluminium is better than, say, zinc, in terms of weight, but zinc would actually give better definition. It is just too heavy. Ideally we would have liked magnesium but, again, it is an industry that is not particularly well serviced. There are magnesium die-casting foundries around, but few compared to zinc or aluminium, and it’s very specialised. We just couldn’t find a manufacturer that was interested in our small quantities.
“So the three shiny circular plates that you see on top of the Newton are chrome-plated brass lens holders. There is a lot of brass in there and obviously the glass is heavy too. Plastic lenses wouldn’t have been possible: you can’t get the quality with plastic and also you’d have to do the tooling for an injection mould, which would be hideous.”
Despite the problems with heavy brass objective lens holders, the Newton NM1’s outer plastic casing is one aspect of its design which is truly lightweight.
“If you strip the casing off you find a totally self-supporting microscope structure inside,” says Rick. “The plastic is there for two main reasons. One is to protect everything that is inside the microscope, and the other is to keep out the light. The plastic casing is attached to the chassis in a way that it gives quite a lot of resistance to shock. The idea is that it won’t transmit those forces into the optical or mechanical systems. So the plastic is intended to absorb the energy by bending. It’s just the same plastic as a mobile phone: what we call PC/ABS, so it’s a blend of Polycarbonate and Acrylonitrile Butadiene Styrene.”
Rick: “The clear case is just a publicity shot to show the insides, it could never work like that, except in the dark.”
Taking it to Market
Unlike some of Rick’s work, the Newton NM1 is a project he and his colleagues have been involved with from start to finish. The final stage is distributing and selling the product, whether that’s direct to individuals, or as package deals with pharmaceutical manufactures, educational establishments and medical missions.
“We are doing the whole thing,” insists Rick. “We had the idea, got funding, made the prototypes, trialled them in a laboratory, in the field in Africa and various places; we’ve gone to manufacture, and now we are just in the process of launching it and looking for distributors. The website has gone live and there is an on-line shop.
“Obviously you have got to claw back your investment, but some of the proceeds allow us to give what we hope are going to be very large discounts to the people who we designed it for in the first place; so they are doctors working in poor countries in the field, trying to diagnose tropical diseases.
“Some of those organisations can’t afford to spend £6000 on a microscope and when they do, it is kept in a room. And something as simple as a lighting failure could render it useless. But if we can give them microscopes at heavily-discounted prices, say a couple of hundred pounds – that sort of thing – it could seriously change things.” TF
Rick Dickinson: Designer Update (Part 2) can be found here: Part 2