From our lab: the first images
IN-VISION’s optical engineers have put together a very simple but impressive test setup. Here, we share a few images of the results.
A quick note before we begin: the following images are far from perfect. They are not polished, Instagram-ready technology shots. Instead, they show what experiments actually look like. That is precisely why they are particularly useful for explaining the concept of PLM.
Structured optical energy instead of flat projection
We use the PLM first to illuminate the entire projection area and then to focus the light increasingly tightly onto a single point. Even with the naked eye, it is easy to see how the intensity continues to increase.
- The optical power is therefore distributed across the illuminated areas in the image.
The images show phase-modulated light generated with the DLPM670VIS.
Freely programmable focus
Achieving a large depth of field involves a familiar trade-off in optics: to increase the depth of field, the aperture is stopped down, which reduces the amount of light. With PLM, this trade-off can be avoided by shifting the focus. In this example, the projected Mickey Mouse is focused first on the rear plane and then on the front plane.
The static image shows a projection cone whose shape can be varied considerably.
Since the image is created by diffraction, higher diffraction orders, and speckle patterns exist in the images path. These effects can be reduced to a minimum by optimizing computer-generated-hologram (CGH)- algorithms as well as implementin simple Fourier-optics into the optical setup.
Beam Steering by Software
What looks a little like event lighting demonstrates how a beam of light can be steered using the PLM chip. Instead of a large scanning mirror moving along several degrees of freedom, the four (AH: two million, 2048x1088 pixel) million micromirrors of the DLPM980 perform this task.
Being able to control every single micromirror without any crosstalk at a level of 16 steps, gives us a programmable diffraction grating digitally programmable. This enables us to not control the image plane, but to control any imageplane after the PLM-chip. We control the whole Light-Field.
Our Test Setup
We kept the test setup very simple. It uses the DLPM980VIS Development Kit for wavelengths from 420–680 nm, featuring a 0.98-inch device with a resolution of 2048 × 1088 pixels. It has an onboard FPGA with IN-VISIONS Software, which enables you to integrate the device in the system of your choice, ranging from a very basic optical setup, by using our GUI, to a highly automated machine integrating the device with our API. The Kit is equipped with optical input and output trigger as well as high speed interfaces to ensure the integration of high speed applications.
The laser light source, breadboard and spacers are standard Thorlabs components; the fully compatible DMD mounting plate comes from IN-VISION. All together can be also purchased from IN-VISION – just contact us to receive an offer.
To demonstrate the function of the PLM chip more clearly, we project directly from the DMD without any additional optics. And yes, we cheated a little: we used the fog machine left over from the last Christmas party to make the beams more visible.
