Structured light methods are used by many commercial products on the market today. Many such systems using white light projectors while many line gages use standard red laser diodes. However, in recent years there has been much claimed about using blue light, polarized light and partially coherent systems to obtain better performance. Unlike interferometers, moving from red to blue light for a system using only geometric shape information does not gain an automatic advantage from the shorter wavelength. The sensitivity metric does not have a wavelength component to it. But there are other factors that can improve gage performance. The ability to measure some feature is also a function of other parameters such as signal to noise ratio, reflectivity variations, and depth-of-field over which a clear pattern can be seen. This paper will explore the theoretical and experimental data relating to what works and what can be expected from variations on the old methods.
The accurate measurement of surface roughness is essential in ensuring the desired quality of machined parts. Today the
most common method to check roughness is to use a contact stylus profiler. There are many challenges for the
application of a contact stylus for measuring the surface roughness of machined parts especially for the hard to access
areas such as slots, deep holes and curved pockets. This study proposes a surface roughness measurement technique for
these hard to access areas that are based on the measurement of the statistical analysis of the specular and scattered light
intensity. In order to solve the accessibility issue, a miniaturized roughness measurement sensor with an Ø3mm diameter
was designed using a dual laser emitting configuration. This dual laser approach makes the system more durable and
reliable for different materials and machining processes such as polishing, lapping and precision grinding. This paper
will present initial research results that demonstrate the applications of this approach to real industrial parts. Tests were
performed to evaluate the sensitivity and feasibility of the proposed technique with various machined surfaces and
Measurement of surface finish in industrial manufacturing has traditionally been done by means of either visual
comparison with reference plates or by the use of contact stylus based profilers. There are many challenges associated with contact profilers such as stability during measurement in an industrial environment, damage and wear of the tip, measurement in tight spaces or on curved surfaces and just the limited amount of data obtained by a linear scan of the stylus. Many alternative methods have become available such as white light interferometry, focus based systems, and even laser scatter. This paper will present the result of testing of the commercially available methods with particular emphasis on the fine surface finishes demanded in today’s manufacturing, then presents some alternative methods that show strong potential to address some of the challenges mentioned above that are not in wide use today. The analysis will specifically explore some of the physical mechanisms that affect the stylus based measurement, as well as the limitations of many of the optical approaches related to view angle and diffraction limited resolution consequences. The area of confocal imaging will be specifically explored as to how it might be used to obtain more complete data on very fine surface finishes.
Using the grazing incidence pumping technique with a 600 mJ, 500 ps background pulse and a 250 mJ, 200 fs main
pulse the lasing emission from a molybdenum target has been studied. A flat field spectrometer designed to observe the
X-ray laser emission in both the first and second orders was used to record the time integrated data. Time resolved data
was obtained by installing an Axis-Photonique PX1 X-ray streak camera to observe the first order output from the
spectrometer whilst retaining the time integrated second order observation. In this paper both time integrated and time
resolved data are presented for a range of grazing angles, target lengths, delays between pumping pulses and pumping
energy. Comparisons are also drawn with simulations from the Ehybrid and Medusa codes. An additional experiment is
also described in which a two colour pumping method is used to investigate lasing at short wavelength from high Z
targets (Z ≥ 62).
We present a review of recent development and applications of soft x-ray lasers, undertaken at the PALS Centre. The applications benefit from up to 10-mJ pulses at the wavelength of 21.2 nm. We describe the pumping regimes used to produce this soft x-ray laser, and outline its emission characteristics. A significant fraction of applications carried out using this device includes probing of dense plasmas produced by IR laser pulses and high-energy-density-in-matter experiments. Results obtained in these experiments are reviewed, including x-ray laser probing of dense plasmas, measurements of transmission of focused soft x-ray radiation at intensities of up to 1012 Wcm-2, measurements of IR laser ablation rates of thin foils, and probing high density plasmas by x-ray laser Thomson scattering
The Axis-Photonique PX1 fast X-ray streak camera records the temporal structure of events with picosecond accuracy.
Using a potassium iodide photocathode the streak camera has been characterised for the effects of space charge. In a
recent grazing incidence pumping X-ray laser experiment the streak camera was coupled to the output of a flat field
spectrometer to observe first order diffraction. The second order was observed using a CCD camera. In this paper data
is presented from this experiment comparing the brightness of the X-ray laser emission with the dispersion of the
streaked image both temporally and spectrally (non temporal direction). Consequently measurements of the dynamic
range of the streak camera are made. The results are compared with data from previous experiments.