How high-tech laser projectors work


Before we proceed to how laser projectors work, you need to note that we are referring to laser as light source. Nonetheless, this should not kill your interest on how they operate. As you shall soon find out, LASER projectors work in a very interest manner.

How laser projectors work

I know you are hyped about how this sophisticated masterpiece works. Laser projectors function just like other projectors only that the light source is different.  While many other projectors use LED, and arc xenon light sources, the laser projector uses lasers as a source of light. Laser projectors have numerous benefits compared to other projectors. For instance, there is no overheating which occurs when arc xenon light sources are used. Additionally, laser projectors have a prolonged lamp life, up to even 25,000 hours which is far better than 20,000 hours of a xenon arc lamp.  Other advantages include lower power consumption and high-quality images.  There is no screen door effect on laser projectors. However, this ultramodern technology is prohibitively expensive. The least expensive laser projector goes for about $ 2000. Now let us jump into how laser projectors work.

How lasers themselves work

Lasers inside these types of projectors work using the same principles that other lasers employed anywhere works. These lasers could be either gas, glasses, or crystal type. The type of laser matters only a little. Current excites electrons on glasses, gases, or the crystal which in turn moves to another orbit (from low orbit to a higher orbit). When this is done, a photon (light particle) is emitted.  It is then that we can see light from the lasers.

How do laser projectors work?

The lasers emit different colors. However, laser projectors only require red, green, and blue light lasers to work with. There are two laser and single laser projectors that use blue laser diodes only. You will find this in more detail in the discussion of the types of laser projectors below.

how LCD projectors work

Now after the light is emitted from the laser, other basic principles of normal projectors kick in.  Let us take a look at how modern LCD projectors work. LCD projectors use different light sources, most xenon arc lamp is directed towards dichroic mirrors. The mirrors filters light and reflects only primary color light, red, blue and green. The light is then directed towards LCD screens. There are three LCD screens each for each light color, red blue and green. The LCD screens have pixels that either allows the light to pass through or block it depending on how electrons excites it. The light from each LCD panel is combined using dichroic crystal which now produces a clear multicolored image.

Enter the LASER projector

This means that after the light from the diodes hits the chips, laser projectors do not operate in any way different from how modern LCD projectors work. However, there is a big difference between how digital light processing projectors work and how LCD projectors work.

Once the primary light color are successfully generate, they can directed towards 3 LCD screens that have pixels which are either on or off.  This is the case where the LCD are used. however, when using digital light processing projectors, light is director towards digital micro-mirror device (DMD). Digital micro-mirror device has millions of tiny mirrors which are electronically tilted or re-positioned to  reflect. The light is either reflected through lenses or to a heat sink. The mirrors are tilted at a frequency of 1000Hz. This is how digital light processing projectors work

Pros and cons of the laser projector
Pros

The first advantage of these types of projectors is prolonged lamp life.  For instance, Xiaomi laser projectors are rated 25000 hours. It means that when using it for eight hours every day, the lasers will require changing after 9 years. However, before 9 years are over, there is the likelihood of other technological advancements that will make them either obsolete or better.

The second advantage is that they turn on to full brightness immediately THEY ARE powered. Other lamps such as xenon arc require time to warm up. No time is needed for warm-up when using laser projectors.

The third advantage is that the brightness level remains stable for long periods which is not the case with the other lamp projectors.

The other advantage is that the power consumption for laser projectors is impressively lower than that used by the xenon lamps. It also means that the heat generated is far lower for laser projectors than it is with other lamps.

cons

The main disadvantage of laser projectors is that they are unbelievably expensive. They cost at least $ 2000 each. People are not willing to spend on laser projectors yet.   The second problem is that laser projectors will have to be discarded once the lasers become worn out. Today, there is not technology that allows the change of laser lamps because of their ridiculously long life span.

Types of laser projectors
RGB three laser projectors

RGG three laser projectors Three types of lasers are used for this type of projector. One laser produces red light, the second one blue, and the last one green. This light is then manipulated by the LCD, DLP, or the LCoS chips to produce images on the screen. The advantage of this type of laser is that high-quality images are produced.  The laser projectors of this type are used in theaters and cinemas because they are very expensive. They present brightness uniformity alongside exceptional color representation.

Two  lasers projectors

You could be wonder which one of the three colors is sacrificed when making two lasers projectors. On the contrary, two colors are done away with, the red and the green light lasers. The two laser projectors have both lasers emit blue light. And how are the green and the red light produced you ask? Well, one of the laser lights is used to excite a yellow phosphorous that produces yellow light. The light from the phosphorus is then manipulated using dichroic filters to produce red and green light. Now we have three primary colors, blue from the other laser diode and red and blue from the yellow phosphorous. The three lights are then directed towards the DLP, LCD, or LCoS chips.

Single laser projectors

A single laser projector uses a single laser as the name suggests. It is unsurprisingly the least expensive type of laser projector.  The cost is reduced by the fact that only a single laser diode is used. And which laser color is used? I know you may have guessed it now from the two laser projector knowledge gained above. Yes, it is a blue light laser diode. How then do the other two primary colors come to be? The single laser light is split into two beams, one of the beams is used to ignite yellow phosphorous which produces yellow light. Using dichroic filters, green and red light are produced. Now that we have three primary color light,  the beams can be directed towards the DLP, LCD, or the LCoS chips to process the light.

Hybrid laser projectors

You might be fascinated to learn that it is possible to use lasers and LED light sources together in hybrid laser projectors. And again, the blue laser diode is used.  The LED used is give the red light. And where do you get the green light? Just like it was the case with a single laser and two laser projectors, the blue light from the laser is divided into two beams. The first beam is used is directed towards the LCD, DLP, or whatever chip is used.  The second beam is directed towards a green phosphorus wheel which once excited gives out the required green light. The three beams are directed towards the DLP, LCD, or the LCoS chips to process the light.

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