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2+ Imaging
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
Tobias Nöbauer, Alipasha Vaziri
To allow for convenient removal or exchange of the MLA during alignment, a precision magnetic base plate can be used. Since MLA focal lengths are usually in the order of tens of microns to millimeters, it may be inconvenient to place the camera sensor directly into the back focal plane of the MLA due to the necessity to remove the filter glass plates that are often permanently attached to the sensor package in front of the active surface, or other mechanical restrictions. Instead, it is possible to use relay optics: depending on FOV, magnification and resolution, standard off-the-shelf optics, such as 1:1 macro objectives or a back-to-back pair of photographic prime lenses, may provide sufficient performance; otherwise, more specialized objectives used in machine vision applications can be explored. Mounting the camera on a micrometer linear stage is useful for repeatable alignment.
Diagnostic and other applications of MTF equipment
Published in Tom L. Williams, The Optical Transfer Function of Imaging Systems, 2018
The basic MTF equipment in which the techniques described here were implemented, is illustrated in figure 12.1. The object generator consists of a slit illuminated with radiation modulated at a fixed frequency by a mechanical chopping disc. The slit is mounted on a small linear stage and can be moved perpendicular to itself and to the optical axis of the equipment, by a stepper motor. The complete object generator is mounted on a rotary stage, also driven by a stepper motor, that can rotate it about the optical axis in order to vary the azimuth of the slit.
A Fibre-optic Strain Measurement System to Monitor the Impact of Tunnelling on Nearby Heritage Masonry Buildings
Published in International Journal of Architectural Heritage, 2022
S. Acikgoz, P.R.A. Fidler, M. N. Pascariello, C. Kechavarzi, E. Bilotta, M. J. DeJong, R.J. Mair
Prior to the field application, the cables were calibrated and validated for strain and temperature sensing. Figure 2 describes the tests carried out using a bespoke aluminium rig and linear stage. In Figure 2a, one end of the rig is fixed while at the other end a linear stage with a stepper motor is used to apply displacements. The fibre was fixed to the linear stage using custom-designed and manufactured clamps (with dimensions 40x40x20mm, see Figure 2b). These clamps were made from aluminium alloy plates and featured stainless steel fixing components, to ensure durability. In these tests, displacement increments were applied to the fibre to generate strains up to 2500. The results of eight different tests conducted on different gratings are presented in Figure 2c. As described earlier by Eq. 2, the relationship between the central wavelength and applied strain was linear with negligible hysteresis upon unloading and reloading. The mean value and standard deviation for the gauge factor k was 0.742 ± 0.006. In order to assess the effect of potential material creep or slippage between the various coating layers and the clamps, several of the cables were left under an applied strain of 2500 for a period of 7 days. No significant strain changes were observed.
A Novel Test Rig for the Investigation of Ball Bearing Cage Friction
Published in Tribology Transactions, 2021
Thomas Russell, Farshid Sadeghi, Wyatt Peterson, Saeed Aamer, Ujjawal Arya
The entire sensor–fixture plate assembly is mounted on linear stages for motion along the X, Y, and Z axes. The X position of the cage is controlled manually on a linear stage equipped with a 0.1--resolution micrometer. The Z stage is computer controlled with resolution of 0.01 All three stages have a total travel distance of 25 mm. In addition, the entire ball–servo motor assembly is mounted on a manual translation stage with 125 mm of travel to allow for approximate positioning and easy disassembly. The BCFTR has two configurations for controlling the Y position of the cages shown in Fig. 1. The position control configuration uses a 0.1--resolution micrometer to control the Y axis linear stage. This is used to take measurements of cage friction at specific locations inside of the cage pocket, particularly for situations where the surface of the ball is not in contact with the cage wall. The second configuration used to control the Y position of the cage is the load control configuration. In this setup, the Y position of the cage is controlled with a suspended weight system. Unlike the position control configuration, the ball and the cage wall are placed into contact prior to the onset of an experiment. This system provides a repeatable method for the application of different loads between the ball and cage segment.
In-ear earphone design-oriented pressure sensitivity evaluation on the external ear
Published in Ergonomics, 2022
Yan Yan, Yonghong Liu, Jiang Rui, Kexiang Liu, Yujia Du, Haining Wang
A hand-held electronic mechanical algometer (YISIDA-DS2; Hong Kong, China), which comprises an electronic liquid crystal display (LCD) display pressure gauge and indenters of different sizes, was used in this study. The pressure algometer’s accuracy was ±0.2% of the displayed value, and the mechanical algometer’s measuring range was 0–50 N with a resolution of 0.01 N. As shown in Figure 1(a), four indenters were redesigned to adapt to the ear surface in different regions since it varies, and each ear region is relatively small. Generally, indenters 2 and 4 are used to measure the concha, antihelix, antitragus, centre of crus, and superior cavum concha. Alternatively, the tragus and antitragus, and tear canal were measured using indenters 1 and 3, respectively. The four indenters were used for all participants in the same manner as mentioned above. All four indenters were designed and manufactured in aluminium (Figure 1) with sharp edges, a top surface radius of 1.5 mm, and tolerance based on GB/T1804 and GB/T1184-K. In addition, the indenter’s tip was designed parallel to its connecting part to ensure an accurate measurement of the actual force applied to the external ear. Furthermore, to ensure the participants’ safety, the indenters should be sufficiently large to avoid epidermal penetration. An electronic mechanical algometer was firmly coupled with a stepper motor to enable the algometer forward or backward movement with continuous traction. As shown in Figure 1, a customised 3D-printed connector was designed to attach the electronic mechanical algometer to a linear stage sliding table controlled by a stepper motor. The main part of the sliding table and stepper motor was connected with a 3-way tripod head to freely adjust the indenter’s direction, and a tripod supported the equipment. Finally, data from the electronic mechanical algometer were transmitted through a cable to a laptop computer.