Dichroic mirror spectral range?

In summary, a dichroic mirror can reflect light in a range of wavelengths, but the typical range is between 530nm-535nm. It would be possible to make a mirror that reflects only a specific wavelength, but it would be expensive and require a lot of work.
  • #1
geneiusxie
9
0
Hi guys,

I'm wondering about exactly if there is some sort of range that a dichroic mirror would reflect, like a green mirror would reflect between 532nm - 600nm or something. I'm pretty sure a green dichroic mirror doesn't only reflect only 532.00000 nm and not 533 nm or something.

But what is the typical wavelength range for dichroic mirrors? And would it be possible to make a dichroic mirror so precise that it would only reflect light that deviates no more than 1% from the design wavelength? For example, would it be possible to build a mirror that only reflects 530nm - 535 nm?
Thanks.

-Gene
 
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  • #2
I've seen filters that filter out all but a 5 nm range centered on the Hydrogen Alpha emission, which is 656.28 nm. I'd be willing to bet you can get smaller.

Also, the angle of the light has a drastic effect on this range. In any optical system, a smaller F/ratio, and thus a more sharply converging light cone will reduce the effectiveness of the filter more than a larger F/ratio system.
 
  • #3
Huh. I was wondering if it was possible to make a mirror that would seem 100% transparent to the naked eye, but would reflect 100% of the light of a green laser.

If you stack 3 mirrors for red, green, and blue the size of a TV and put an activated carbon material designed to absorb 95% of the material that goes through the mirrors, and combine that with a laser projector, we could get a laser projector that offers much darker blacks than standard projectors in normally-lit rooms.

Of course, dichroic mirrors seem to be pretty expensive right now, so we'd need a cheaper way to make those mirrors too. We'd also probably have to use a gradient on the wavelength that the mirrors reflect due to some areas of the screen being at different angles than others. And we'd need a way to scatter the light so people can see it. And then if the light gets scattered, the dichroic mirrors wouldn't really work because of the different angles.

Wow never mind then lol.
 
  • #4
geneiusxie said:
Hi guys,

I'm wondering about exactly if there is some sort of range that a dichroic mirror would reflect, like a green mirror would reflect between 532nm - 600nm or something. I'm pretty sure a green dichroic mirror doesn't only reflect only 532.00000 nm and not 533 nm or something.

But what is the typical wavelength range for dichroic mirrors? And would it be possible to make a dichroic mirror so precise that it would only reflect light that deviates no more than 1% from the design wavelength? For example, would it be possible to build a mirror that only reflects 530nm - 535 nm?
Thanks.

-Gene

Spectral characteristics of dichroics (or any other dielectric mirror) can be designed with (AFAIK) nearly any spectral lineshape. The major companies are Omega Optical:
http://www.omegafilters.com/Products/Curvomatic

Chroma:
http://www.chroma.com/products

Semrock:
http://www.semrock.com/

Dielectric filters can have passbands as narrow as a few nm, AFAIK. If you want even more narrow passbands (say for solar observation), you have to go with a Fabry interferometer.
 
  • #5


I can provide some insight into the spectral range of dichroic mirrors. Dichroic mirrors are optical filters that selectively reflect certain wavelengths of light while allowing others to pass through. The spectral range of a dichroic mirror depends on the type of coating used on the mirror and the angle of incidence of the light. Generally, dichroic mirrors have a broad spectral range, covering multiple wavelengths of light. For example, a green dichroic mirror may reflect light in the range of 500-600nm, with a peak reflectance at 532nm.

It is possible to make a dichroic mirror with a very precise spectral range, but it would require careful design and fabrication of the mirror coating. Such a mirror would need to have a very narrow bandwidth and high reflectance at the desired wavelength range. This can be achieved by using multiple layers of thin films with different refractive indices and thicknesses, known as a multilayer coating.

However, even with precise design and fabrication, it is unlikely that a dichroic mirror could be made to reflect only a 1% deviation from the design wavelength. There will always be some level of imperfection in the coating and the angle of incidence of the light can also affect the reflectance. Therefore, while it is possible to make a dichroic mirror with a very narrow spectral range, it may not be practical to achieve such a precise reflectance.

In summary, the spectral range of a dichroic mirror depends on the type of coating and angle of incidence, and it is possible to make a mirror with a very precise spectral range but it may not be practical to achieve a reflectance with only a 1% deviation from the design wavelength.
 

1. What is a dichroic mirror?

A dichroic mirror is a type of optical filter that reflects certain wavelengths of light while allowing others to pass through. It is made up of multiple layers of thin films with varying refractive indexes, which produce a spectral response based on the angle of incidence of light.

2. How does a dichroic mirror work?

A dichroic mirror works by using the principle of interference. When light hits the multiple layers of thin films at different angles, some wavelengths of light will be reflected while others will be transmitted. This creates a spectral response, which can be tuned by adjusting the angles and thickness of the films.

3. What is the spectral range of a dichroic mirror?

The spectral range of a dichroic mirror refers to the range of wavelengths of light that it can reflect or transmit. This range is typically determined by the type and number of layers in the mirror and can vary from UV to infrared wavelengths.

4. What factors affect the spectral range of a dichroic mirror?

The spectral range of a dichroic mirror can be affected by several factors, including the materials used in the thin films, the angle of incidence of light, and the thickness and number of layers in the mirror. The design and manufacturing process also play a role in determining the spectral range.

5. How is the spectral range of a dichroic mirror measured?

The spectral range of a dichroic mirror can be measured using a spectrophotometer, which can accurately measure the amount of light reflected or transmitted at different wavelengths. The spectral range is usually represented as a graph or table showing the percentage of light reflected or transmitted at various wavelengths.

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