Read more about his landscape and wildlife photography techniques in Camera Settings for Amazing Sunrise and Sunset Landscapes. On the other hand, more dust and smog (at sunset) can have the effect of scattering light across a greater region of the sky, creating a larger drape of colors, whereas sunrise colors tend to be more focused around the sun. When saturating a pixel, the UV projector instead causes the pixel to transition along a range of different colors before finally reaching black at full saturation (Figure 2). This occurs because the cyan, magenta, and yellow color channels in the photochromic material increase in saturation at different speeds when exposed to UV light (yellow requires 7s, cyan 40s, and magenta 60s to reach full saturation). Using the three primary colors of natural light and diodes to reflect the wonderful sunset and rainbow, can transform your space and make it instantly romantic and interesting. To solve this, we removed the top casing of the visible light projector, which created additional space. We then detail how we selected and mounted the UV projector for saturating the dyes and how we calibrated it with the visible light projector used for desaturating the dyes.
In contrast, by using a UV projector, we can create the texture without the lengthy desaturation step by saturating individual pixels directly. In contrast, prior work was not capable of achieving these transitions since it required the entire texture to be saturated to black with the UV LED before a new color could be created using the desaturation capabilities of the visible light projector. The origin of projection from the UV projector is 5cm behind the lens and the frustum has a width of 17.2cm and a height of 9.7cm at the position of the platform, which is similar to the visible light projector and is sufficient to cover the entire 17cm platform. As seen in Figure 7, the output spectrum of the UV projector has a peak at 372nm, but also produces light output between 360nm and 400nm, with significantly less light intensity the further the wavelengths are from the peak. A UV projector with a deeper UV light source would further accelerate the dye saturation since the absorption peaks of the dyes lie at wavelengths significantly below 360nm. However, we opted for a 365nm projector as they are more commonly used in industry and hence are more readily available.
Angling the UV projector, however, led to a collision with the visible light projectors casing. Projector mounting heights: To determine the mounting heights of the projectors, we analyzed both projectors’ frustums and their overlap with the rotating platform. We selected our projector (model: LUXBEAM LRS-UV-HD) based on three requirements: First, the output spectrum of the UV projector must overlap with the absorption spectra of the cyan, magenta, and yellow photochromic dyes. We then mounted the UV projector at a position that maximizes the overlap of its projection with the visible light projector, while also maximizing its own overall projection size, and setting its distance such that its focal length is on the platform. We use the same hardware setup as PhotoChromeleon , i.e. the same visible light projector and rotating platform, but we replaced the UV LED with a UV projector (LUXBEAM LRS-HD-UV). Figure 7. Output spectrum of our UV projector (LUXBEAM LRS-UV-HD) and the UV LED from PhotoChromeleon . We used a spectrometer (ThorLabs CCS200) to measure the output spectrum of the UV projector and took the data on the absorption spectra of the photochromic dyes from the data sheets that are provided by the manufacturer (Yamada Chemicals).
Finally, we calibrated the output of the UV projector with that of the visible light projector to ensure that saturation and desaturation commands sent to both projectors target the same pixels. Thus, the visible light projector can be mounted at the same height as the platform with the object. However, since the UV projector’s frustum is symmetric, we had to mount the UV projector at a height of 4cm since the projector would otherwise project half the image underneath the platform. However, it’s the quality and capability of its electronic interfaces that first caught my attention. It’s so idyllic, in fact, that some professional photographers will only book appointments during golden hour! STARGAZERS across the globe will be treated to a Harvest Moon this September. One side effect of bringing up your shutter speed is that it will darken the exposure. Pay attention to shutter speed when using a reflector. Figure 2. Grayscale preview: Physical result of projecting a dithered grayscale image onto a physical sample using only the UV projector. To this end, we provide two functions: (1) a fast grayscale preview, and (2) a color-to-color transition on a per-pixel basis. We projected the grid pattern onto a flat physical object and compensated for visible deviations between the two projections by adjusting the position and angle of the UV projector manually.