Is there an approximate equation to compute the effect of Strehl Ratio into spot size?

The expression used to calculate the minimum focusable (difraction limited) spot size is: Size=(1,22*lambda/sin(theta)) considering that already from a LASER source some imperfections reduces...

10 November 2018 5,009 0 View

What determines the "amount of depth perception" in stereo microscopes?

I have seen a microscope setup in a lab with a variable stereo base (realized with symmetric movable mirrors covering different widths from the CMO). This shall in principle modify the stereopsis...

02 March 2015 8,422 3 View

What is the limit "c" or "the speed of light in vacuum"

It is accepted that nothing can travel faster than c or the speed of light in a vacuum. But (and sorry if this question was asked before in RG), is the limit "the speed of light in vaccuum" whose...

06 July 2013 8,716 18 View

What is the best way to determine and interpret logistic regression coefficients?

I have some responses behaving as yes/no (e.g. whether a treatment was succesful or not) and a number of preoperative and surgical parameters that may be predictors of it. Now I can make logistic...

10 November 2012 1,760 3 View

Is there a simple yet more advanced time response predictor than the Kalman filter?

Is there a simple yet more advanced time response predictor than the Kalman filter?

10 November 2012 9,791 14 View

What is the maximum number of Zernike polynomials that can be fitted before reaching numerical unstability?

I am looking and searching for a paper (I think published on JRS or JCRS, but I am not quite sure) that determined based on specific aberration maps of humans, the number of zernike coefficients...

07 August 2012 5,495 1 View

Effect of Strehl on Spot Size

The expression used to calculate the minimum focusable (difraction limited) spot size is: Size=(1,22*lambda/sin(theta)) considering that already from a LASER source some imperfections reduces...

01 January 1970 1,580 0 View

How to Eliminate cosine error and abbe error in LASER measurement system(for example Rhenishaw XL80)?

I like to do project in laser measurement system. My objective is to eliminate or reduce the cosine error, abbe error in Laser measurement system. I have Rhenishaw XL80 system. Please tell the...

28 February 2021 4,890 3 View

How can we limit artifacts caused by rotation in fiber photometry?

We are trying to run fiber photometry experiments for long time scales, but we get these sinusoidal artifacts that come up. We think they may be caused by twisting of the fiber optic subject...

25 February 2021 568 1 View

How to measure angle between laser travel path and machine axis in Laser Measurement system?

25 February 2021 1,987 3 View

How can I simulate the optical absorption spectrum of a biomaterial (like DNA or protein) in COMSOL?

I need to simulate the optical properties of a biomaterial, namely DNA, in COMSOL. Basically I need to simulate the IR absorption spectrum of a cylinder filled with a 'concentration' of DNA. I am...

21 February 2021 3,043 3 View

What is the reason of the received optical signal to be slimmed down in multi-mode fiber?

What is the reason of the received optical signal to be slimmed down in multi-mode fiber? I have 4 km multi-mode fiber

03 February 2021 1,105 10 View

Why it is not permissible to correct all 5 classical optical aberration (spherical, chromatic, coma, astigmatism, curvature of field) simultaneously?

When first order paraxial optics is expanded to third order optics (i.e. sin x~ x-x3/3! instead of sin x~x) , these 5 optical aberrations result in. What is the rigorous mathematical proof that,...

26 January 2021 8,666 4 View

Difference between Second-harmonic generation and Two-photon absorption?

Hello Dear Researchers, I am confused about the Difference between Second-harmonic generation and Two-photon absorption? Can anyone describe the two phenomena briefly in the physical picture? What...

24 January 2021 9,912 5 View

Is it possible that the single-pass absorption exceeds 50%?

Dear researchers It's well-known that the maximum light absorption of any structure can not be greater than 50%. Is it possible that the single-pass absorption exceeds 50%? How?

17 January 2021 2,335 7 View

What can cause laser beam polarisation fluctuations?

Dear colleagues, We have observed large fluctuations in laser power in our setup and traced them down to fluctuations in laser beam polarisation. Attached is a schematic of the relevant part of...

14 January 2021 7,505 4 View

How an unusual visual effect at the Monte Carlo casino can be obtained?

At the Monte Carlo casino, I saw an unusual advertising image. It rotated around a vertical axis and seemed suspended in the air; there was no screen behind it. The image was bright and colorful....

03 January 2021 9,119 5 View