Investigation of the Efficiency of Vibro-Isolating Supports of Optical Tables

Asian Journal of Applied Science and Engineering, Volume 3, No 1 (2014) ISSN 2305-915X

Copyright © 2012, Asian Business Consortium | AJASE 8


Copyright © 2012, Asian Business Consortium | AJASE Page 19

Asian Business Consortium realizes the meaning of fast publication to researchers, particularly to those working in competitive and dynamic fields. Hence, we offer an exceptionally fast publication schedule including web based & paper less prompt peer-review by the experts in the field and immediate publication upon acceptance.



Investigation of the Efficiency of Vibro-

Isolating Supports of Optical Tables

Vladas Vekteris, Artūras Kilikevičius, Vadim Mokšin & Andrius Gedvila

Department of Mechanical Engineering, Vilnius Gediminas Technical University, LITHUANIA

ABSTRACT

The main tasks of this work are to investigate experimentally the vibration behaviour of the optical tables and the floor structure and to establish the vibration transmission factor of vibro-isolating supports. It is established that the vibration frequency of the table is low, about 1 Hz. Therefore it is possible to mount the laser and optomechanical convergence system of multiple pump beams to the optical table, because the transmission factor of vibro-isolating supports varies from 0.879 to 0.968. Key words: Optical Table, Vibro-Isolating Supports, Vibration Acceleration, Vibration Transmission Factor

1 INTRODUCTION

asers and their systems are sensible to vibrations and acoustic noise. Noise and vibrations can arise from sources inside or outside the building, for example, from passing cars, wind, heating, ventilation and air conditioning systems, etc [1].

Therefore precision balances, optical microscopes, lasers must be well isolated from vibrations to ensure their proper performance. Ultrastable Fabry Perot cavities used to stabilize lasers also require vibration isolation [2]. Although these cavities are primarily sensitive to horizontal motion, vertical motion of the ground and optical table can distort the cavity and thus displace the reflecting surfaces [2]. Similarly, in precision atom interferometer measurements, a single optical element must be constrained to move such that it accelerates uniformly with respect to free falling atoms over a time scale as long as 1 s [2, 3]. In atom interferometer measurement of g, for instance, it is necessary to stabilize the position of a mirror to a small fraction of the wavelength of light for times approaching 1 s. The typical level of background vibrations in the frequency range between 0.1 and 10 Hz would completely wash out the interferometer fringes [2]. A mechanical spring can adequately isolate key elements from background vibrations, but only in a certain frequency range. Vibrations occurring at frequencies below the natural resonance frequency of the spring-mass system will pass through the spring virtually undiminished. Above the natural resonance frequency of a spring-mass system with negligible damping, vibrations are reduced by a factor proportional to ω-2 [2]. Standard optical tables floating on compressed air have resonance frequencies around 2 Hz and thus isolate the equipment from any ground motion faster than ≈2 Hz [2]. Isolating against background vibrations slower than 2 Hz requires a different approach. Custom designed optical tables are

L



usually used in laser centres and laboratories to mount such equipment. The aim of this work is to evaluate the efficiency of vibro-isolating supports of optical tables.

2 OBJECT OF INVESTIGATION

Rigid tables assembled on vibro-isolating supports are shown in Figure 1 (2, 3). Vibration behaviour of two similar tables located at different technological premises was investigated. Arrangement of accelerometers is shown in Figure 2.

Figure 1: Experimental vibration isolating tables, which are rigidly connected to one another: 1 – accelerometer mounting place; 2, 3 – investigated table; 4 – Machine Diagnostics Toolbox (type 9727, Bruel&Kjaer)

Figure 2: Arrangement of accelerometers on vibration isolating tables: 1 – block; 2 – accelerometer (type 8344, Bruel&Kjaer); x, y, z – coordinates A lightweight honeycomb table structure was used. Mechanical properties of the honeycombs depend on the size of the cells, thickness of the walls and material properties. Honeycomb tables are characterized by excellent vibration damping properties; they are much lighter than conventional granite tables. One of the most important properties of the vibro-isolating supports of such tables is vibration transmission from floor to the table top. In order to establish vibration transmission characteristics two points were chosen (Figure 2).



3 RESULTS OF INVESTIGATION

Results of measurements of vibrations of the floor and the 1st table are presented in Figure 3 and Figure 4. Statistical parameters of the vibration acceleration signal are presented in the Table 1.

Figure 3: Vibration acceleration of the 1st table measured in vertical direction (a) and vibration acceleration spectrum (b) (results obtained from accelerometer 8344 data)

Figure 4: Vibration acceleration of the floor surface measured in vertical direction (a) and vibration acceleration spectrum (b) (results obtained from accelerometer 8344 data) Table 1: Statistical parameters of the vibration acceleration signal (1st optical table)



Vibration transmission factor of vibration isolating supports was calculated as follows:

15.108447.0

09716.0

f

t

x

xtr

S

Sk

1)

where

txS is the standard deviation of the vibration acceleration of the table; fxS is the

standard deviation of the vibration acceleration of the floor structure. Results of measurements of vibrations of the floor and the 2nd table are presented in Figures 5–7. Statistical parameters of the vibration acceleration signal are presented in the Table 2.

Figure 5: Vibration acceleration of the 2nd table (with additional mass) measured in vertical direction (a)

and vibration acceleration spectrum (b) (results obtained from accelerometer 8344 data)

Figure 6: Vibration acceleration of the floor surface measured in vertical direction (a) and vibration acceleration spectrum (b) (results obtained from accelerometer 8344 data)



Figure 7: Vibration acceleration of the 2nd table (without additional mass) measured in vertical direction (a) and vibration acceleration spectrum (b) (results obtained from accelerometer 8344 data) Table 2: Statistical parameters of the vibration acceleration signal (2nd optical table)

Mea

suri

ng

po

int

Statistical parameter

Arithmetic mean, m/s2

Standard deviation Sx, m/s2

Standard deviation of the mean,

m/s2

Minimum value xmin,

m/s2

Maximum value xmax,

m/s2

Variation, m/s2

Sum

Ta

ble

wit

h a

dd

itio

na

l m

ass

On

th

e ta

ble

surf

ace

-1.49198E-4 0.06362 9.94039E-4 -0.198 0.206 0.404 -0.611

On

th

e fl

oo

r

surf

ace

-1.34346E-4 0.06575 0.00103 -0.145 0.186 0.331 -0.55

Ta

ble

wit

ho

ut

ad

dit

ion

al m

ass

On

th

e ta

ble

surf

ace

5.30981E-4 0.05783 9.03581E-4 -0.158 0.164 0.322 2.1749

On

th

e fl

oo

r

surf

ace

-1.34346E-4 0.06575 0.00103 -0.145 0.186 0.331 -0.55



Vibration transmission factors of vibro-isolating supports of the 2nd table were calculated by formula (1):

,9676.006575.0

0.06362)(

f

t

x

xmasswithtr

S

Sk

.8795.006575.0

0.05783)(

f

t

x

xmasswithouttr

S

Sk

Obtained results show that transmission factor of the vibration isolating supports varies from 0.8795 to 1.15.

4 CONCLUSIONS

In accordance with the results of experiments, the following conclusions can be drawn:

Vibration behaviour of vibro-isolating supports of optical tables was investigated, vibration transmission factors were established.

Transmission factor of the vibro-isolating supports of the first table reached value of 1.15; therefore additional vibration isolation is required.

REFERENCES

[1] Kilikevičius, A.; Vekteris, V. 2006. Vibration sources acting the computer stand. Mechanika 2006: Proceedings of the 11th international conference, April 6-7, 2006, Kaunas University of Technology, Kaunas, Lithuania, 168-172.

[2] Weiss, D. S.; Young, B. C.; Chu, S. 1994. Precision measurement of ħ/mCs based on photon recoil using laser-cooled atoms and atomic interferometry. Applied Physics B: Lasers and Optics, 59, 3, 217-256.

[3] Young, B. C. 1997. Ph. D. thesis. Stanford University.

Why Open Access ???

“In the traditional publishing model, readers have limited access to scientific papers; authors do not have copyright for their own papers, and cannot post their papers on their own websites, which presents a significant barrier to the sharing of knowledge, as well as being unfair to authors. Open access can overcome the drawbacks of the

traditional publishing model and help scholars build on the findings of their colleagues without restriction”

Submit your next manuscript at- www.abcjournals.net ABC Journals is a unique forum to offer open access to all of its articles. Now ABC Journal’s portfolio is over eight journals, which publish both online and in print.

http://www.abcjournals.net/



Asian Journal of Applied Science and Technology

(Peer reviewed international journal) ISSN: 2305-915X (print); 2307-9584 (Online)

Universal Impact Factor 0.6351; ICV 2012: 5.20

Open Access Philosophy Under Open Access Philosophy, AJASE will not charge for the

access of its journals. This will ensure that a large percentage of

students, scholars, researchers and practitioners will be able to

benefit from the research published through ABC journals.

Moreover, this process will also enable authors’ papers to receive a

higher ranking. A greater number of people being able to access

and consequently refer to papers will mean a higher citations and

Impact Factor for ABC journals. Following are advantages of Open

Access Philosophy:

1. The full text of all issues of AJASE is freely available to anyone,

online.

2. Your research work will be indexed and abstracted in the internationally

reputed databases and search engines immediately after publication.

3. Open Access increases the number of downloads, page views, citations etc.

increasing the rate of dissemination of your research work manifold.

4. It is inferred from past researches that the papers published under "Open

Access Philosophy" are four times more likely to be cited than the papers

published under "Non-Open Access Philosophy"

Peer Review Policy

Paperless, web-based peer review system, professional and helpful suggestions from reviewers. Articles in this

journal have undergone a rigorous blind peer review system, based on initial editor screening and involving in-

country and international refereeing, ensures that articles meet the highest standards of quality. Most ABC

journals have ISSN with IMPACT FACTORS. It facilitates our scholars, researchers, scientists, professors,

corporates, governmental research agencies, librarians etc., in a more positive way in their research proceedings.

Faster Turnaround Time

Many journals take many months, even years to publish research. By the time papers are published, often they become

outdated. AJASE publishes papers in the shortest possible time, without compromising on quality. This will ensure that

the latest research is published, allowing readers to gain maximum benefit. We provide feedback instantaneously and

furnish details of the outcome within about 5 - 6 working days of submission of your research paper. This enables

research scholars to use their time effectively on the actual research rather than on the follow ups.

Strong International network & Collaboration

We have exposure to wide range of industries across geographies and worldwide connect through international

colleagues and thereby the recognition. We work in collaboration with extremely creditable companies, academic

institutions, reputed publication units, government bodies and research firms. By publishing with us, you join ABC

Global Research Community of 50,000 scientists / researchers.

For Details- go through the link: www.ajase.weebly.com

http://ajase.weebly.com/



ASIAN BUSINESS CONSORTIUM

www.abc.us.org

Asian Business Consortium (ABC) is a multi-disciplinary research, training, publishing, digital library supporting and service house. Though founded in 2010 as the Business and Computing organization of Asia, it was reconstituted as the ABC in 2011. It has been working for creating and nurturing talents in USA, Malaysia and Bangladesh since its inception. As ABC is going global, it intends to open offices in Australia, Germany, Japan, Pakistan, and other Asian countries in near future. The objectives of consortium are solely centered round the welfare and humane attitude of the founders who enthusiastically took up this noble cause and materialized it with a view to promote research and educational activities for the encouragement of scholars to develop their knowledge, to publish their analysis oriented scientific researches in international Journals, books, the task of organizing workshops, seminars, conferences, training, personality development programs and allied services. In addition to research activities, ABC provides a good number of scholarships to the poor and meritorious students at various levels of education throughout the world. It plays an important role in the field of research by funding research projects and publishing the research papers. This consortium will unquestionably become the mouth-piece of the dark horses and unacknowledged scholar whose endowed and commendable contributions shall be provided an outlet keeping in mind the greater good of the larger society of the world. ABC runs well indexed international referred journals for creating a platform to share the thoughts of professionals, scholars and academicians throughout the world. Each journal home page provides specific information for potential authors and subscribers. Open access policy, the quick review process, rich editorial boards and quality publications have already made ABC Journals unique. ABC Journals are published under the direct supervisions of renowned academicians of the world. ABC runs the following international referred journals for creating a platform to share the thoughts of professionals, scholars and academicians throughout the world.

Bangladesh Publications

Asian Accounting and Auditing Advancement (4A Journal); ICV 5.09

Asian Business Review (ABR); UIF 0.1809

Asian Journal of Applied Sciences and Engineering (AJASE); UIF 0.6351; ICV 5.20

Global Disclosure of Economics and Business (GDEB) USA Publications

ABC Journal of Advanced Research (ABC JAR)

International Journal of Reciprocal Symmetry and Theoretical Physics (IJRSTP)

Engineering International (EI)

American Journal of Trade and Policy (AJTP) Malaysia Publications

ABC Research Alert (Online)

Asian Journal of Humanity, Art and Literature (AJHAL)

ABC Journal of Medical and Biological Research (ABC-JMBR)

Asia Pacific Journal of Energy and Environment (APJEE) Each journal home page provides specific information for potential authors and subscribers. Open

http://jmbr-my.weebly.com/

http://apjee-my.weebly.com/



access policy, the quick review process, rich editorial boards and quality publications have already made ABC Journals unique. ABC Journals are published under the direct supervisions of renowned academicians of the world. Collaboration in Conference: ABC considers high-quality conference papers for publication. Please contact us for detailed information. Collaboration in Publishing: If you like to start writing a book, propose a new journal or advertise in ABC journals, please feel free to contact us.

Asian Business Consortium is an Independent Research House Committed to Publishing and Delivering Superior, Peer-reviewed Standard Research

abcDNA Scientists The service for scientists provides easy access to global networking and collaboration. Join or start your own on-line research projects with unique identity. Find collaborators with desirable research skills and access to key equipment for your research. Perform global searches for scientists in your area of expertise. Monitor literature, case reports, conferences, patents and available grant opportunities. Visit: www.abc.us.org

abcGATE Indexation abcGATE is a journal indexing and ranking site The service for research journals' administration allows easy indexation of research journals in real time as well as online access to up to date information, statistics and analytical data. This service improves journals’ performance and the efficiency of research publishing through evidence-based decisions. abcGATE also aids in the areas of excellence through multi-parameter evaluation of scientists, research groups, divisions and faculties. Visit: www.abc.us.org

ABC Journals ABC Journals: a new era of publishing. This service helps an author to grow from a local level to a global one as well as providing complete research article publication solution. ABC Journals helps to professionally manage articles from your location and automatically delivers your contribution to our site. This service accepts peer-review and tracks manuscripts online and builds up relations with authors, reviewers and readers as well as increasing the international awareness of research publication. Visit: www.abc.us.org

3900 Woodhue Place,

Alexandria, VA 22309, USA

Email: [email protected]

Rd 4, Shyamoli

Dhaka-1207, Bangladesh


Pantidalam, Kuala Lampur

Malaysia


Investigation of the Efficiency of Vibro-Isolating Supports of Optical Tables

Documents

Transcript of Investigation of the Efficiency of Vibro-Isolating Supports of Optical Tables