Clase 05:Mechanical Supports

Dr. Alejandro Farah

OptoMechanics

Instituto de Astronomía, UNAM

Posgrado de Ingeniería, UNAM

content…

2. Mechanical Supports

Understanding the influence of mechanical support systems

in the optical components.

2.1.3 Definición de fase, velocidad de fase, superposición de ondas y

velocidad de grupo.

2.1.4 Principio de Huygens.

Posgrado de Ingeniería, UNAM

…first of all…a few words…

spatial stability,

position and rotation,

failure,

human error

…

Posgrado de Ingeniería, UNAM

The phase of an oscillation or wave is the fraction of a complete cycle

corresponding to an offset in the displacement from a specified reference

point at time t = 0.

Phase is a frequency domain or Fourier transform domain concept, and as

such, can be readily understood in terms of simple harmonic motion.

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

Posgrado de Ingeniería, UNAM

Assumption: light is a harmonic wave (sinusoid)

Phase speed of a wave: is the rate at which the phase of the wave

propagates in space.

The phase speed is given in terms of the wavelength λ (lambda) and

period T as

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

Posgrado de Ingeniería, UNAM

Phase difference

Equal phase (or cophased)

Out of phase

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

Posgrado de Ingeniería, UNAM

2.1.3 Definición de fase, velocidad de fase, superposición de ondas y

velocidad de grupo.

If two interacting waves meet at a point where they are in antiphase,

then destructive interference will occur.

Posgrado de Ingeniería, UNAM

It is common for waves of electromagnetic (light, RF), acoustic (sound) or

other energy to become superposed in their transmission medium.

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

Posgrado de Ingeniería, UNAM

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

When that happens, the phase difference determines whether they reinforce or

weaken each other. Complete cancellation is possible for waves with equal

amplitudes.

The principle of superposition of waves states that the resultant displacement at a

point is equal to the vector sum of the

displacements of different waves at that

point.

Posgrado de Ingeniería, UNAM

2.1.3 Definition of phase, phase velocity, superposition of waves and

group velocity.

Chromatic interference is seen in sea foam, which is

made out of plankton. It is an example of the naturally

occurring interference.

Posgrado de Ingeniería, UNAM

2.1.4 Huygen´s principle.

It recognizes that each point of an advancing wave front is in fact the

center of a fresh disturbance and the source of a new train of waves; and

that the advancing wave as a whole may be regarded as the sum of all

the secondary waves arising from points in the medium already

traversed.

Posgrado de Ingeniería, UNAM

HomeWork: 2.2

- Talking about teslescopes and astronomical instruments:

i) How does interferometry work?

ii) Is it possible for everyone to do optical interferometry?

- What is a ray trace software? And mention at least 3 commercial

softwares to do that.

Posgrado de Ingeniería, UNAM

P R O Y E C T O de O P T O M E C Á N I C A

Objetivo:

Realizar el diseño conceptual y preliminar de los soportes

optomecánicos para el instrumento astronómico

RATIR.

Metas particulares:

- Proponer métodos de soporte de componentes ópticos a nivel conceptual.

- Evaluar el diseño de todos los componentes mecánicos de soporte

propuestos para el proyecto.

- Realizar el cálculo de esfuerzos, desplazamientos y rotaciones de los

diferentes sistemas desarrollados.

- Comparar el desempeño calculado con los requerimientos y especificaciones

del instrumento.