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depth of focus

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Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003753
EISBN: 978-1-62708-177-1
.... This gives a resolution limit of d 1 /2. Fig. 10 The definition of the half-angle, α, subtended by an aperture (in this case, the objective aperture) Fig. 11 The depth of focus of an optical system, h , is the distance from the plane of optimal focus within which the beam diverges...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005641
EISBN: 978-1-62708-174-0
... in.) thick AISI 1020 steel revealed that the optimum position of focus was 2 mm (0.08 in.) below the surface. When the beam was focused 4 mm (0.16 in.) below the surface, the depth of penetration was almost the same as that for the 2 mm (0.08 in.) focus depth. The general consensus is that the optimum...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001445
EISBN: 978-1-62708-173-3
... mm (0.08 in.) below the surface. When the beam was focused 4 mm (0.16 in.) below the surface, the depth of penetration was almost the same as that for the 2 mm (0.08 in.) focus depth. The general consensus is that the optimum position for the focal point is below the surface, but the exact distance...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003533
EISBN: 978-1-62708-180-1
... on the sample is transferred to the viewing screen to produce magnification Fig. 3 Illustration showing how depth of focus is dependent on specimen pixel size and aperture size Fig. 4 Emission of (a) secondary electrons as a function of angle of incidence and (b) backscattered electrons...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006769
EISBN: 978-1-62708-295-2
... order of magnitude to approximately 10 nm in routine instruments, with ultimate values below 3 nm. Useful magnification thus extends beyond 10,000× up to more than 100,000×, closing the gap between the light microscope and the transmission electron microscope. The depth of focus, ranging from 1 μm...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001754
EISBN: 978-1-62708-178-8
... of focus when the surfaces examined are very rough. If this lack of depth of focus is a problem, use of SEM is recommended. Preparation of a metallographic section for examination requires careful selection of the area to be characterized. This area must be chosen to represent the unique features...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006763
EISBN: 978-1-62708-295-2
... surface is in focus. Closing down the aperture (higher f-stop) increases the depth of focus. In macrophotography, it is also useful to have reference locator photographs available that show the overall appearance of a component undergoing a failure analysis. As close-up macrophotographs are taken...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001370
EISBN: 978-1-62708-173-3
...: Incident laser beam power Incident laser beam diameter Absorptivity Traverse speed of the laser beam across the substrate surface Parameters such as weld design, shielding gas, gap size for butt welds, and depth of focus with respect to the substrate also play important roles...
Book: Machining
Series: ASM Handbook
Volume: 16
Publisher: ASM International
Published: 01 January 1989
DOI: 10.31399/asm.hb.v16.a0002168
EISBN: 978-1-62708-188-7
... length lenses. Focal lengths usually range from 100 to 250 mm (4.0 to 10.0 in.). Focal position can be optimized above, below, or on the surface of a workpiece, depending on the desired results. Most often, the focus lies below the surface at a depth that is 5 to 15% of the metal thickness. The best...
Series: ASM Handbook
Volume: 2A
Publisher: ASM International
Published: 30 November 2018
DOI: 10.31399/asm.hb.v02a.a0006502
EISBN: 978-1-62708-207-5
.... Types of Lasers The key factor for procedure development is the selection of optimum independent and dependent processes. The independent process variables for laser welding include incident laser beam power, incident laser beam diameter, traverse speed, absorptivity, shielding gas, depth of focus...
Book Chapter

Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003240
EISBN: 978-1-62708-199-3
... and testing applications as a noncontacting tool for displacement, strain and vibration studies, depth-contour mappings, and transient/dynamic phenomena analyses. Specific applications of optical holography in nondestructive evaluation include: Detection of debonds within honeycomb-core sandwich...
Book Chapter

Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003240
EISBN: 978-1-62708-199-3
... omitted from the figure for the sake of clarity. If the original object is three-dimensional, the virtual image is a genuine three-dimensional replica of the object, possessing both parallax and depth of focus. However, if the configuration of the optical system or the wavelength of light used during...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006684
EISBN: 978-1-62708-213-6
.... Fig. 3 Relationship between the numerical aperture and the color of light on the depth of focus of a light microscope. Courtesy of the Carl Zeiss Co. Fig. 4 Axio Imager.Z2m upright light microscope. Courtesy of Zeiss Microscopy Fig. 5 Schematic of the light path through a light...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006677
EISBN: 978-1-62708-213-6
... on a polymer substrate imaged with the (a) scanning electron microscope and (b) helium focused ion beam Fig. 53 Palladium nanorods grown on a sacrificial template of ZnO nanowires. The depth of focus is evident in the high resolution in both the foreground and the background. Fig. 63 MoSi 2...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005631
EISBN: 978-1-62708-174-0
..., consideration should be given to documenting and establishing respective nominal values and bound values for the controllable aspects of the process, some of which are: Laser: Total power, focus optic arrangement (determining power density, spot size and caustic waist profile, depth of focus, angle...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003720
EISBN: 978-1-62708-177-1
... by intergranular separation. The SEM provides good depth of focus to observe topological features of the fracture surface. Modern SEM instruments also typically have x-ray spectroscopic attachments that allow elemental analysis of constituents on (or near) the specimen surface. This can be very helpful in failure...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006668
EISBN: 978-1-62708-213-6
... spheres results in blurring of larger spheres, while spheres of all sizes are in focus with the SEM due to better depth of field. Fig. 13 (a) Line scan across an etched pearlite sample surface. (b) Effect of beam diameter, d s , on secondary electron signal intensity. A beam with d s much...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005610
EISBN: 978-1-62708-174-0
... sections, showing keyhole-type behavior at the respective sharp focus settings. However, differences in the characteristics of sharply focused beams also result in differences in the measured depth and width of each weld. The measured weld depths produced at the respective sharp focus settings show...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005618
EISBN: 978-1-62708-174-0
...-Cutting Thermal Processes Principles of Laser-Drilling Processes Principles of Laser Shock-Peening Processes Laser Output Piercing Focusing Characteristics Focus Position Assist Gas Types Gas Supply Gas Purity Assist Gas Flow Rates Material Considerations Surface...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003754
EISBN: 978-1-62708-177-1
... are corrected in the objective and eyepiece correction is not needed. These lenses are useful when using digital cameras that do not require an eyepiece. Flat-field, or plano-type, objectives correct for curvature of field, where the outer edges appear out of focus when the field of view appears focused...