The expansion of the world economy has enabled easy access to suppliers of optical components and systems throughout
the world. Unfortunately, all manufacturers do not adhere to the same quality standards, so the need for accurate and
cost effective inspection has never been greater. To address this growing demand, an economical platform for evaluating
the performance of visible, NIR, and LWIR lens assemblies has been developed and will be presented.
A compact low-cost LWIR test station has been developed that provides real time MTF testing of IR optical systems and
EO imaging systems. The test station is intended to be operated by a technician and can be used to measure the focal
length, blur spot size, distortion, and other metrics of system performance. The challenges and tradeoffs incorporated
into this instrumentation will be presented.
The test station performs the measurement of an IR lens or optical system's first order quantities (focal length, back focal
length) including on and off-axis imaging performance (e.g., MTF, resolution, spot size) under actual test conditions to
enable the simulation of their actual use. Also described is the method of attaining the needed accuracies so that derived
calculations like focal length (EFL = image shift/tan(theta)) can be performed to the requisite accuracy. The station
incorporates a patented video capture technology and measures MTF and blur characteristics using newly available lowcost
LWIR cameras. This allows real time determination of the optical system performance enabling faster
measurements, higher throughput and lower cost results than scanning systems. Multiple spectral filters are also
accommodated within the test stations which facilitate performance evaluation under various spectral conditions.
A simple benchtop apparatus has been built, to measure the x-ray imaging properties of fluorozirconate-based glassceramic
x-ray storage phosphor materials. The MTF degradation due to stimulating light spreading in the plate is lower
in comparison to optically turbid screens resulting in higher image MTF. In addition, the degree of transparency, or the
amount of light scattering at the wavelength of the stimulating (laser) light is adjustable by means of the glass preparation
process. The amount of stimulating exposure required for plate readout is generally higher than in previous systems,
but well within the range of commercially available laser systems, for practical readout times. The effects of flare
or unwanted readout due to back-reflection from the imaging plate is also less than in previous systems.
A novel telecentric scanning system has been developed that is able to rapidly read out the latent image stored in the
translucent imaging plates. This system features a reflective primary scan mirror to achieve telecentricity, optical correction
for scan line bow, and the design should enable the construction of a relatively inexpensive scanner system for
the translucent x-ray storage plates.
The introduction of third generation thermal imagers brings a new challenge to the laboratory evaluation of the thermal
imager resolution performance. Traditionally, the Modulation Transfer Function (MTF) is used to characterize the
resolution performance of the thermal imager. These new third generation of thermal imagers can be categorized as
sampled imaging system due to the finite pixel size of the elements comprising the focal plane array. As such, they
violate the requirement of shift invariance required in most linear systems analyses.
We present a number of approaches to measuring the resolution performance of these systems and conclude that source
scanning at the object plane is essential for proper MTF testing of these sampled thermal-imaging systems. Source
scanning serves dual purposes. It over-samples the intensity distribution to form an appropriate LSF and also generates
the necessary phases between the thermal target image and the corresponding sensor pixels for accurate MTF
calculation. We developed five MTF measurement algorithms to test both analog and digital video outputs of sampled
imaging systems. The five algorithms are the Min/Max, Full Scan, Point Scan, Combo Scan, and Sloping Slit methods
and they have all been implemented in a commercially available product.
This paper describes a desktop, turnkey metrology system tailored for the measurement of the surface topography of
small optical components such as contact and intraocular lenses and molds. The system incorporates a wavefront sensor
that provides interferometric accuracy while being relatively insensitive to vibration. Highly accurate measurement of
the radius of curvature (typically better than .02%, 2 micrometers on a 10 mm radius part) is obtained using a patented
data reduction system. The system also measures toroidal and aspherical systems and can be readily adapted to the
measurement of longer radius parts. The system is capable of measuring surface topography in less than 10 seconds
after part placement and is usually operated by unskilled personnel. Full three-dimensional topography is reported
including peak-to-valley and root-mean-square surface departure, and Zernike polynomials. This paper provides an
overview of the optical configuration and software algorithms that enable the highly precise capability of the device.
A system that accurately positions a 35mm film camera or HDTV sensor at the infinity focus image plane of a large-aperture
tracking telescope in the field is described. A beam of collimated laser light is scanned across the entrance pupil
of the telescope while tracking the movement of the centroid of the image formed at the sensor. In the case of an HDTV
camera, the electronic signal is sampled directly, whereas for the 35mm film camera a secondary re-imaging system is
employed to capture diffusely scattered light from the film surface.
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