3D printer lens

Creating 3D Printed Lenses and a 3D Printed Camera with Stereolithography

The idea for a fully 3D printed camera—a machine with many complex components—has been floating around Formlabs since we first experimented with creating 3D printed lenses.

Our applications engineer Amos Dudley took on the challenge and created the first fully 3D printed, interchangeable lens camera, produced entirely on a Formlabs SLA 3D printer.

The first fully 3D printed, interchangeable lens camera was produced entirely on a Formlabs SLA 3D printer.

Formlabs Clear Resin and stereolithography (SLA) 3D printing can create transparent objects that, with some post-processing, can be made optically clear. Formlabs' latest SLA 3D printer, the Form 3+, takes clarity one step further by using a flexible resin tank that reduces peel forces, resulting in clearer parts with smooth surface finish.

A camera lens is an exciting test case for the possibility of optically clear prints because the results are so easily seen and measured on film.

Read our guide for a list of finishing methods to create clear 3D printed parts for a variety of applications, from optics to light pipes to fluidics.

Making a functional lens starts with proper lens design. Optical design software helps lens designers predict the behavior of a lens and the constraints the lens will place on a camera.

Professional lens designers use optics packages such as Zemax and Code V, but these programs can cost thousands of dollars. Free, open-source software packages like Optical Ray Tracer are suitable alternatives.

Commercial camera lenses use multiple elements to correct for the optical distortions that commonly affect spherical lenses, such as spherical aberration, coma, and field curvature. For the sake of simplicity, the 3D printed camera is designed around a single spherical lens element.

The lower image shows how a smaller aperture increases focus.

Each side of a spherical lens is a section of a sphere with a given radius. Inserting the refractive index value for Clear Resin (1.5403) into Optical Ray Tracer shows that a symmetrical lens with a spherical radius of 50 mm focuses at approximately 47.5 mm from the center of the lens.

A single objective lens for a camera needs to balance optical power with distortion. A low-power, long focal length lens will have less distortion, but a narrow field of view. It is difficult to aim a camera if the field of view of its lens is too narrow. Reducing the aperture size helps to eliminate some coma distortion, as seen above.

A good compromise between these factors is a focal length of 50 mm, which is wide enough to position a subject within the frame.

The lens is modeled as the intersection of two spheres and a cylinder.

Once the lens is designed, it can be modeled in a CAD program. Since the lens is symmetrical, this is as simple as intersecting two 50 mm spheres at the right distance. The distance defines the radius and thickness of the lens, but doesn’t radically affect the optics. The lens was designed to be 40 mm in diameter with a 2 mm cylindrical edge.

If 3D printing on a Formlabs SLA 3D printer, consider different orientations and resolutions for 3D printing your lenses:

• A lens 3D printed horizontally may have layer line artefacts toward the center of the lens’s axis.
• A lens 3D printed perfectly vertically may be subject to some distortion caused by the additive process.

The clearest lenses were printed at a 30° angle relative to the build platform, with supports placed only along the edge to prevent support marks on important lens surfaces.

Testing different methods of polishing lenses, including hand sanding and machine polishing.

We tried three methods of polishing lenses to optical clarity: manual sanding, automated sanding, and dipping.

We used a range of sandpaper and micromesh pads with grits from 400 to 12000, in increments of 200, and polished lenses to a very smooth finish. This was done slowly and with a lot of care to clean the lens between grit levels and to eliminate scratches from the previous level before moving on to the next.

At around 3000 grit, SLA 3D printed lenses become glossy and very smooth to the touch. By 12000 grit, they are reflective.

To make an optically clear 3D printed lens, all layer lines need to be completely eliminated, which wasn’t possible by hand. Even though the lenses were smooth to the touch, reflections still appeared blurry, and there were still micro-scratches visible when holding the lenses at a shallow angle to the light.

The lens was clear as a magnifying glass, but as a focusing lens it wasn’t accurate enough.

It was hard to control the amount of material sanded off in the early stages of hand sanding, where the bulk of the layer lines were being removed. The next step was to try an automated method for reducing layer lines.

Amos designed and printed a lens polishing machine in hopes of reducing some of the error.

The speed of the lens’s rotation in the lens polishing machine is controlled by an Arduino.

Within the lens machine, the lens is rotated against the inside of a dish with the same spherical radius. The dish also rotates, but off axis to the lens by 45 degrees, and at a different speed.

The lens is connected to a servo motor with a kinematic coupling that combines 3D printed parts, springs, and small rivets. The coupling keeps the lens firmly, but flexibly pressed against the dish and allows it to “wobble” as it rotates. The dish holds a small amount of water and diamond lapping compound as an abrasive, and is made of the same Clear Resin as the lens.

The machine quickly reduced layer lines, but it couldn’t easily be used for the whole process. The dish would have to be replaced between polishing layers so grit wouldn’t be transferred to finer levels of polishing.

Unfinished 3D printed lenses rest on a build platform after being washed in isopropyl alcohol.

While gluing some prints together, Amos noticed that 3D printed lenses became significantly clearer when coated in a viscous material like epoxy, and decided to dip the lenses in liquid resin and then post-cure them under UV light. The viscous resin filled layers and scratches, forming a completely smooth surface.

Resin has a tendency to form bubbles when agitated, such as by dipping a lens, but these can be removed by turning the lens upside down over the resin tank and letting the resin gather and drain from the center.

The layer of resin should be as thin as possible while still eliminating layer lines. The last remaining bubbles were pulled of with a syringe, and the lens was post-cured completely under a UV lamp before dipping the other side.

Three stages of resin-dipped lenses, with the final lens on the left.

Resin-dipped 3D printed lenses are extremely smooth, with clear and sharp surface reflections. This technique can be used for other SLA prints as well to give them an even smoother finish, although it does tend to reduce detail.

The dipping process also alters focal length slightly, so Amos designed and printed a lens testing device. The device has screw threads that allow the lens to move closer and further from the imaging plane by turning the wheel, and experimentally check the focal distance of the lens.

The 3D printed lens tester mounted to a digital camera for instant feedback.

Is it possible to make 3D printed optics and lenses with multiple elements and more functionality? Try 3D printing your own lenses and lens tester, or a whole camera if you’re adventurous!

Download the 3D printed camera .STL files on Pinshape.

Learn more about Amos’s process for designing the entire 3D printed camera on his blog, and see the camera in action in our blog post featuring photos taken by the world’s first 3D printed, interchangeable lens camera.

Curious the see and test 3D printed SLA parts firsthand? Request a free 3D printed sample part to your office.

Request a Free Sample Part

You Can 3D Print and Build This 164mm f/2.5 Lens for Less Than $15

Photographer Felix Steele has created a design for a 3D-printed 164mm f/2.5 lens that has no fasteners or screws, uses affordable glass elements, and can be built at home for less than $15.

Steele created the design as the first major project of his online resource for open-source photography projects called Pixels and Prisms. The build features 23 “significant parts” as well as 15 pegs and is held together with nothing more than glue. Despite the simple design, the lens has a focusing mechanism and a fully adjustable aperture that houses elements in fixed tubes.

“Every photographer has different needs when it comes to lenses — in price, speed, and focal length. The Pixels and Prisms 163mm f/2.5 telephoto lens is a customizable optical system that offers a low-cost, open-source alternative to commercial lenses through 3D-printing,” Steele explains.

“As a photographer, the experience of building this lens was a valuable method of connecting with the principles which underlie much of my work. When a change in lens design affects your depth of field or sharpness, you develop an acute understanding of, and appreciation for, the equipment and techniques that you employ. ”

The finished lens features coverage for a full-frame camera with an aperture range between f/2.5 and f/11 via a 12-bladed aperture diaphragm and is made for the EF mount.

“For under $15, Pixels and Prisms is a viable low-weight lens option for travel, portrait, or street photographers, as well as a cost-effective entry point into telephoto photography. The aperture and zoom system can even be modified to work with any lens element, so long as an extender is added to the front of the optic,” he continues.

Stelle says that because of its flexibility, the lens design can serve as a means of providing an accessible way to get to specialized focal lengths — like 600mm — that doesn’t require a large investment. He says he plans to iterate on the design in the future and will be working on making the form factor more convenient as well as improving the optical quality.

“The process of designing and creating this telephoto lens was a three-month endeavor that started with the creation of an optical formula. The print files… are open for you to download — and the following will allow you to source and fit a lens element to go with them,” he explains.

The only parts of the lens that can’t be 3D printed are the glass optics, and for this Steele used Surplus Shed to acquire achromatic (two-part) lenses. He says that eBay is another option, but to make this particular lens builders will need one with a diameter of about 65mm.

“The Surplus Shed website features a focal length alongside each lens, and often, Ebay sellers include similar information. You will need to perform your own measurement for completely reliable results, though,” he says.

“First, balance the lens upright (on its edge) on a table or desk. Then, position a light source on the other side of the room, and direct it towards the lens element. The lens will focus the light at some point above your surface. The exact point is easily located by moving a sheet of paper to and from the lens: a halo will appear that drifts in and out of focus as you move the paper. Finally, mark the point of sharpest focus and measure the distance from the lens element. This is your focal length (although I would recommend double-checking your calculation),” he continues.

“The result is a measurement that can be used to create a simple lens casing, to test image clarity and focusing before moving on to the finished project. Shift your lens into focus in front of your camera until you are satisfied by the quality of your element. Alternatively, slide your lens element along a tube of cardboard. Any part that will allow you to test the performance of your lens by making adjustments in distance to the sensor should work here. Once you’re satisfied that you have an acceptable lens, set it aside and begin 3D-printing.”

Steele says that the free online tool Optical Ray Tracer is also helpful in understanding the principles behind the lens.

“The software allows you to free-draw lenses and beams of light, among other functions. It allows you to create loose models of aperture and focal length – but a feature which visualizes the focusing mechanisms that you will be working with is Zoom Lens, a preset stored in their ‘Examples’ library. ”

“I chose a sample portfolio of seven images that illustrate the lens’s technical and creative potential and its excellent optical qualities,” he says.

The first is a simple photo of a lawn, which Steele includes with a version that enlarges the middle to showcase the sharpness.

Below are the other sample images Steele captured with the 3D printed lens:

The full build instructions for the 164mm f/2.5 Pixels and Prisms lens are broken into seven parts: the lens mount, the lens barrel, the outer focusing barrel, the inner focusing barrel, the focus ring, the aperture base, the aperture blades, the aperture pegs, and the aperture ring. Afte that, Steele supplies the build order diagram and building tips to make construction as easy as possible.

The 3D print files and all instructions can be found on Pixels and Prims.

Image credits: Felix Steele, Pixels and Prisms

Transparent 3D Printing Guide

Stereolithography (SLA) 3D printing can produce transparent objects that, after some post-processing, become optically transparent.

Formlabs' latest stereolithographic 3D printer, the Form 3, improves model transparency by using an elastic resin reservoir that reduces forces on the model, resulting in smoother, more transparent parts. 3D printing on a Form 3 in Clear Resin is a great way to produce parts that require light transmission and, with the right post-processing techniques, transparency. nine0003

The following processing methods can be used to 3D print transparent parts for a variety of purposes, from optical devices to light guides and liquid elements. Techniques range from quick solutions to obtain sufficient transparency to specialized techniques for creating optically transparent parts.

Clear and transparent 3D models are ideal for creating transparent prototyping elements, showing internal cavities and details, making LED housings or windows. Formlabs and our customers have used Clear Resin to create an optically clear 100% 3D printed camera lens, Times Square Fresnel lens tiles, light guides, prisms, millifluidic devices, and more. nine0003

Formlabs application engineer Amos Dudley designed and 3D printed a lens for a fully 3D printed camera.

Curious to see with your own eyes what a transparent SLA 3D printed part looks like? We will send a free transparent 3D printing sample directly to your office.

Request a Free Sample

We have tested several post-processing methods for 3D printed Clear Resin parts. In this article, we will cover hand sanding, spray clear coating and resin impregnation. Each treatment option requires a different amount of effort, depending on the required degree of transparency and surface quality. nine0003

Application of : Hand sanding and polishing can be effective on simple shaped models with few fine details, but is not suitable for complex shaped models. With this method, it is very difficult to achieve complete optical transparency.

Hand sanding will require you to sand with very fine grit sandpaper, but with some effort you can sand and polish the parts to the transparency level of a magnifying glass. However, it is very difficult to completely remove all the layer lines with manual processing - if you turn the part at a slight angle to the light, you can notice micro-scratches. nine0003

Instruction : Use sandpaper to smooth the surface, then polish the part with acrylic cleaner and a microfiber cloth.

With approximately 3000 grit sandpaper, transparent SLA 3D printed parts become glossy and very smooth to the touch. After sanding with 12.000 grit, they reflect light. Try different sandpapers and abrasive sheets from 400 to 12,000 grit in 200 increments. Before moving on to the next grit step, slowly and carefully clean the lens and remove scratches from the previous level of sanding. nine0003

Our support site offers a simple step-by-step manual sanding guide that includes an acrylic spray finish.

If all you need is translucency, mineral oil will suffice to create a smooth surface and hide light spots.

We have tested various polishing methods for transparent 3D models, from hand sanding and spray coating to resin impregnation. nine0012