Optical speed sensing system

A method for determining a rotational speed of a rotating object comprising the steps of:

• (a) providing an apparatus including a light source, an optical system, a detector having a single detection region, a power source for providing power to the apparatus, and an analyzer including a Fourier Transform function operable to perform at least one Fourier Transform,
• (b) transmitting a collimated light beam having a selected wavelength with the light source directly at the rotating object, wherein light signals are reflected from the rotating object,
• (c) focusing the reflected light signals onto the single detection region of the detector,
• (d) detecting the focused light signals with the detector,
• (e) generating electrical signals based on the light signals detected with the single detection region of the detector,
• (f) processing the electrical signals with the analyzer including at least one operation with the Fourier Transform finction,
• (g) determining the rotational speed of the rotating object with the analyzer from the processed electrical signals, and
• (h) outputting the rotational speed of the object to a user with the apparatus.

An apparatus for determining a rotational speed of a rotating object comprising:

• optical processing components, including:
• a light source for transmitting a collimated light beam having a selected wavelength at the rotating object, wherein light signals are reflected from the rotating object, and
• an optical system for focusing the reflected light signals onto a detecting means having a single detection region, wherein the detecting means is operable to detect the focused light signals and generate a detected light signal based on light detections with the single detection region of the detector,
• an analyzer for digitizing the detected light signal to produce a digitized detected light signal, including a Fourier Transform function for converting the digitized detected light signal from a first domain to a second domain providing a spectrum including data representative of the rotational speed of the object, the analyzer for analyzing the spectrum to determine the rotational speed of the object and producing an output indicating the rotational speed of the rotating object, and
• a power source for providing power to the apparatus.

An optical speed sensing system for manually determining the speed of a rotating object without requiring a reflective element on the object, the system comprising:

• a collimated light source of a selected wavelength for illuminating an area of the rotating object, wherein light signals are reflected from the rotating object,
• an optical system for collecting the reflected light signals of the selected wavelength and rejecting light signals other than the selected wavelength, wherein the collected light signals are converted to electrical signals,
• a conversion means for digitizing the electrical signals,
• an analysis means including a Fourier Transform function for generating power spectral density data from the digitized electrical signals, the power spectral density data being stored in a first memory,
• a means for displaying a speed spectrum to a user of the system, wherein the speed spectrum is generated from the power spectral density data stored in the first memory and,
• a calculation means for calculating the rotational speed of the rotating object according to a frequency peak in the displayed speed spectrum, the frequency peak being selected by a user of the system.

An optical speed sensing system for automatically determining the speed of a rotating object without requiring a reflective element on the object, the system comprising:

• a collimated light source of a selected wavelength for illuminating an area on the rotating object, wherein light signals are reflected from the rotating object,
• an optical system for collecting the reflected light signals of the selected wavelength and rejecting light signals other than the selected wavelength, wherein the collected light signals are converted to electrical signals,
• a conversion means for digitizing the electrical signals,
• an analysis means including:
• a Fourier Transform means for applying a first Fourier Transform function to generate power spectral density data from the digitized electrical signals, the power spectral density data being stored in a first memory, and for applying a second Fourier Transform function converting the power spectral density data to autocorrelation data, the autocorrelation data being stored in a second memory, and
• an algorithm means operable upon the stored autocorrelation data, wherein the algorithm means includes criteria for automatic determination of the rotational speed of the rotating object from the autocorrelation data, and
• means for displaying a speed spectrum to a user of the system, wherein the speed spectrum is generated from the power spectral density data stored in the first memory, the display of the speed spectrum indicating the rotational speed of the rotating object.