BCAMs at OSI

Contents

Introduction

[05-JAN-25] The Boston CCD Angle Monitor (BCAM) is an optical metrology instrument. Its design and all associated data acquisition hardware and software are open-source. You will find links to drawings, schematics, reports, and manuals at the BCAM Home Page. The BCAM was developed and manufactured by the Brandeis University High Energy Physics (BNDHEP) Department in the years 1999-2021 with funding from the United States Department of Energy.

Figure: A Black H-BCAM (BCAM-HL). We see the front camera lens in a brass holder. On either side are two laser diodes, both turned on for photo. Above and below the lense are the four white LEDs, turned off for the photo. The metalized serial number label is on the lid. The laser safety label is on the other side wall, as shown in this view.

The H-BCAM is a double-ended metrology camera equipped with four laser diode light sources and two white LED illuminators for retro-reflecting targets. Its field of view is 100 mrad × 75 mrad. Its absolute accuracy with respect to its three kinematic mounting balls is 50 μrad rms. Its tracking accuracy is 5 μrad rms across the entire field of view for ranges 80 cm and greater. Its laser positions are known to better than 10 μm rms. The photograph below shows the blue version, which we also refer to as the right-handed H-BCAM. For a photograph of the black left-handed version, see here. To obtain full perforemance, a BCAM must be mounted on

Figure: A Blue H-BCAM (BCAM-HR). Note the tape covering the mounting hole aperture in the cover. A similar piece of tape covers the lower aperture until we secure the BCAM in place with a screw.

The example in the photograph above has 5-mW laser diodes, and so requires a Class II laser warning label. The location of the lens holder, being flush with the front face of the chassis, implies a focal range of the front camera is 1.5 m. The serial number Q0232 is on the lid, and allows us to look up its calibration constants in the BCAM parameter database.

Figure: A Set of Blue H-BCAMs (BCAM-HR) with Data Acquisition Hardware.

The H-BCAM's powerful lasers are intended for use with retroreflecting sphere targets. A sphere made of glass with refractive index 2.0, such as part number 48-895 from Edmund Optics, acts as a retroreflector, as we describe here. We can measure the position of the sphere by looking at the reflection of an H-BCAM laser using the H-BCAM's camera. The sphere requires no electronics. It can endure cryogenic temperatures. The HIE-ISOLDE alignment of cryogenic modules used such spheres within the modules, seen through sapphire windows by H-BCAMs mounted outside the modules on metal plates.

Figure: A HIE-ISOLDE Cryogenic Module Under Construction.

Open Source Instruments (OSI) began manufacturing BCAMs for HEP experiments in 2004. The H-BCAM was designed by OSI in 2012 in collaboration with CERN (Center European Research Nuclear). The H-BCAM was the first BCAM to use the ICX424AL image sensor. Prior BCAMs used the smaller TC255P. We no longer manufacture the original A-BCAM (Azimuthal BCAM) and P-BCAM (Polar BCAM). The TC255P image sensor used by these devices is no longer available. The newer N-BCAM (New Small Wheel BCAM), D-BCAM (Double-Ended BCAM), and H-BCAM (HIE-ISOLD BCAM) are in production for as long as our reserves of the ICX424AL image sensor last. Thereafter we will design new BCAMs around a modern CMOS sensors. The IMX249LLJ from Sony Semiconductor, for example, is a back-illumnated device that we may be able to use for full-performance BCAMs in the future.

Active Versions

[05-JAN-25] In the figures below, we present the varieties of BCAM currently in production at Open Source Instruments Inc. We do not keep these devices on the shelf in any significant quantity, so when you order them, delivery will be roughly twelve weeks. For prices, see our Price List.

See the section below for a selection of photographs showing what these active BCAMs look like. Most have their socket in the back wall, but the H-BCAMs have their sockets in one of their side walls.

Photo Gallery

[05-JAN-25] Here are photographs of all our active BCAMs. For the discontinued A and P versions, see the BNDHEP Catalog.

	Black N-BCAM (BCAM-NL) A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides a camera with ICX424 image sensor. Provides two red laser diode light sources. Contains a Black N-BCAM Head (A2083A). Contains one Black N-BCAM Side Head (A2074C)
	Blue N-BCAM (BCAM-NR) A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides a camera with ICX424 image sensor. Provides two red laser diode light sources. Contains a Blue N-BCAM Head (A2083B). Contains one Blue N-BCAM Side Head (A2074D)
	Black D-BCAM (BCAM-DL) Front A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides two cameras with ICX424 image sensors. Provides four red laser diode light sources. Contains a Black D-BCAM Head (A2086A). Contains two Black D-BCAM Side Heads (A2074E)
	Black D-BCAM (BCAM-DL) Rear A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides two cameras with ICX424 image sensors. Provides four red laser diode light sources. Contains a Black D-BCAM Head (A2086A). Contains two Black D-BCAM Side Heads (A2074E)
	Blue D-BCAM (BCAM-DR) Front A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides two cameras with ICX424 image sensors. Provides four red laser diode light sources. Contains a Blue D-BCAM Head (A2086B). Contains two Blue D-BCAM Side Heads (A2074F)
	Blue H-BCAM (BCAM-HR) Front A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides two cameras with ICX424 image sensors. Provides four red laser diode light sources. Contains a Blue H-BCAM Head (A3025B). Contains two Blue D-BCAM Side Heads (A3026R) First BCAM with ICX424, deployed in HIE-ISOLDE.
	Black H-BCAM (BCAM-HL) Front A Boston CCD Angle Monitor (BCAM) A Long-Wire Data Acquisition (LWDAQ) Device. Provides two cameras with ICX424 image sensors. Provides four red laser diode light sources. Contains a Black H-BCAM Head (A3025A). Contains two Black D-BCAM Side Heads (A3026L) First BCAM with ICX424, deployed in HIE-ISOLDE.

Mounting Plate

[05-JAN-25] All BCAMs mount on three quarter-inch stainless steel balls. We can provide calibrated mounting plates with the steel balls and threaded mounting hole, which you can bolt to another structure using two larger holes, as shown below.

Figure: Drawing of Kinematic Mounting Plate. Plate coordinates in blue.

With our Coordinate Measuring Machine (CMM), we will measure the location of the three balls with respect to the plate coordinate system as shown. These measurements will be accurate to ±5 μm.

Obsolete Versions

[05-JAN-25] The following BCAMs have been manufactured at OSI in the past, are still fully supported by our team, but are no longer being manufactured. The A and P BCAMs are obsolete because they use the TC255P image sensor, which is no longer available. The original H-BCAM, manufactured before 2016, uses two forks to hold the two image sensors, and its chassis is machined out of one piece of aluminum. The two forks are held in place by two screws through the bottom of the chassis. The H-BCAMs manufactured after 2016 have frames screwed to the side walls to hold the CCDs, and the chassis consists of three pieces: a base and two identical flanges for the end walls. Each flange is held in place with four screws.