Panchromatic Laser Speckle Problems: Talking About Panchromatic Laser and ALPD Laser Projection Technology

wheelee

Member
With the development of technology, the projection light source technology has also developed from the original bulb light source to the current laser light source. Hisense released the world's first full-color laser projector this year - Hisense Vidda C1. This Hisense Vidda C1 with the best laser technology and the best picture color is only priced at more than 6,000. Didn't you hear that the full-color laser is very good, why is the price so cheap? Is full color laser really easy to use? Today we will talk about laser technology.

Three-color laser technology
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The principle of the three-color laser is relatively simple, that is, the three-color lasers of red, green and blue are respectively hit on the DMD chip, and the DMD projects the desired image.
The three-color laser has the advantages of higher brightness and wider color gamut in image quality display. But there is a fatal flaw: the speckle problem.​
What is speckle?
Lasers are characterized by high coherence due to their very narrow wavelength bandwidth. After the light is reflected on the screen surface, it enters the eyes of the audience, which can be regarded as the superposition of various coherent wavelets reflected on the screen. What you see is a grainy patch of light and dark, or noise. Speckle is especially noticeable on metallic screens and high-brightness images. Speckled pictures can cause many uncomfortable symptoms, such as dizziness, eye pain, etc.
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Then someone has to ask, is it that serious?

You can look at C1's e-commerce evaluation to know:

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ALPD Laser Technology
ALPD stands for fluorescence laser technology, which is a technology used for image display based on the technical route of laser excitation of fluorescent materials and mixed multi-color laser.

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The basic principle is: use a laser light source to hit the fast-rotating color wheel, because the color wheel is coated with RGB three colors of phosphor powder, and then the phosphor powder excites red, green, and blue light, and then hits the color wheel. On the DMD chip, the desired picture is projected by the DMD.

Why is there no speckle problem with ALPD lasers?
ALPD technology uses laser-excited fluorescence to display other colors. Since the fluorescent material emits light by spontaneous emission of dopant ions, the light emitted by different dopant ions has slight differences in time, and the light is emitted in all directions in the entire space. There is no coherence in time and space, and speckle is not easy to generate from the technical source. Therefore, the ALPD laser technology architecture overcomes the speckle problem in principle compared with the RGB three-primary laser technology architecture.​

Summary:

The above is the problem of full-color laser speckle: Let’s talk about the whole content of full-color laser and ALPD laser projection technology. From the above article, we can see that full-color laser is compared with ALPD laser technology, although there are some obvious advantages in color. , but there is also an inevitable speckle problem, and looking at the screen for a long time is also a great harm to the eyesight. Generally, when buying a projector for home use, you must also hope to protect your eyesight. The picture of ALPD laser technology is also completely enough for home use. Now whether to choose full-color laser or ALPD laser technology, I believe everyone should have their own answers. , in the future, full-color laser technology may be gradually matured, but now, of course, ALPD laser technology is still selected.
 

wheelee

Member
seems like it, that is what some experience,
you know those laser pointers? if you point it at a wall & look closely the light seems to be moving or sparkling, i guess it's the same issue for this
 
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