ON AXIS PARABOLIC MIRRORS
(with high LIDT coatings

(other type of optics - look here)

What's it on axis parabolic mirrors?

On Axis Parabolic (hereinafter - parabolic) mirrors is central part of the surface of paraboloid of revolution.

How parabolic mirrors are commonly used?

Parabolic mirrors  are most commonly used for focusing collimated beam to obtain minimal focal point size
 or inverse task - when customer needs to obtain collimated beam from point source .
 

High Laser Induced Damage Threshold ( L. I. D. T. ) - what is it?

Upon reaching a certain threshold value of the energy density (LIDT) on the surface of the mirror,
reflective coating damage occurs.

The exact value of this LIDT depends both on
--- the mirror itself (the type of reflective coating, the quality of coating and the manufacture of the mirror) and 
--- on the radiation parameters (pulse energy, duration and frequency, work spectral range, total irradiation area, total continuous irradiation time and some other parameters).

The highest LIDT for simple dielectric mirrors,
the average "typical value" is 10-20 J/cm2 (1064 nm, 10 ns, 10 Hz, 1 mm2) 
or about 3-20 kW/cm2 for CW radiation (1064 nm, 1 mm2).

Mirrors with metallic coatings (non metallic substrate) have a lower LIDT,
the average "typical value" is 0.5-2 J/cm2 (1064 nm, 10 ns, 10 Hz, 1 mm2) 
or about 0.5-1 kW/cm2 for CW radiation (1064 nm, 1 mm2).

Using various methods, it is possible to obtain higher LIDT values, for example, for dielectric mirrors to obtain 
up to 50-150 kW/cm2 (CW 1064 nm) and 70-90 J/cm2 (10 ns, 1064 nm).

IMPORTANT! 
When you change the wavelength, pulse duration or irradiation area size - the LIDT value changes strongly nonlinearly,
so only a specialist should make an assessment of the LIDT for your radiation parameters.
 

What are the advantages and disadvantages of parabolic mirrors?

The advantage of parabolic mirrors is complete absence of spherical aberrations (see figure below) and, accordingly,
the possibility of obtaining a diffraction-limited spot (or "ideal" parallel beam) in any configuration.

The disadvantage of parabolic mirrors (versus spherical mirrors) is higher cost and longer delivery terms.

 

What's the "most important thing" in a mirror ("mirror quality")?

Usually, it is very important for the customer
how small a spot in the image plane can be formed by the mirror.
Even if task is inverse (i.e. - "ideal" collimated output beam),
this parameter allows you to estimate important data about output beam divergence.

Also, in some tasks the customer is often interested in the possibility of
obtaining an "ideally flat wavefront" in a collimated beam obtained after reflection from a mirror. 
Be sure to specify whether you need this in your request for the cost of the mirror,
as this can significantly affect the price of the mirror.

  

What determines the spot size in the image plane?

The spot size in the image plane for parabolic mirror depends on tolerance of the mirror surface shape manufacturing and 
diffraction limitations at the operating wavelength.
The general principle is that the closer the spot size to the diffraction limit, the more expensive the mirror is.

 

You may send your request in any form, 
but to speed up the process of preparing a quote, it is better to fill out a special "request form".

You may send additional data for the mirror as additional files in attachment to Your request.